Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：Institute of Electrical and Electronics Engineers Inc.  

Different from human's ears, injured hearing system of birds can be regenerated within two weeks even if their hair cells are damaged by exposure of large sounds. In terms of the regenerative process of birds' ears, it is pointed out that the hair cells hearing the lower frequency are cured first, and then, those for higher frequencies are gradually recovered [1]. However, are the damaged hair cells repaired like this In other words, do the birds regain hearing from the lower frequencies to the higher ones When we assume that the hair cells had their own resonant frequency and detected sounds based on such resonance, different comprehension might be possible on the experimental results in [1]. In this paper, we would like to argue the regenerative process of the injured birds' ears under the hypothesis that the hair cells have resonant system for incoming sounds.

DOI： 10.1109/BMEiCON.2018.8609980

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：Institute of Electrical and Electronics Engineers Inc.  

This paper discusses hearing system of human from engineering point of view, and reports four questions we have now
1) why eardrum is so sensitive and broadband, 2) how middle ear compensates significant impedance mismatching, 3) how sounds are detected by such a small cochlea, and 4) how the sounds are absorbed perfectly without ringing. Discussion is focused on question 3), and new hypothesis based on extraordinary transmission in acoustic metamaterials is proposed.

DOI： 10.1109/USNC-URSI.2018.8602721

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：Institute of Electrical and Electronics Engineers Inc.  

This invited talk introduces how extraordinary acoustic transmission plays an important role to detect sounds in human hearing system. This new approach from engineering point of view is totally different from that of V. Békésy's traveling wave theory which has been widely accepted up to today. To elucidate human hearing mechanism, we focus on architecture of sensory hair cells. That is, the wall of the cell has three-layered structure consisting of plasma membrane, cortical lattice, and subsurface cisternae. Our theoretical study indicates that the plasma membrane and cortical lattice form an extraordinary acoustic transmission system to detect sounds with extremely high resolution and sensitivity, and subsurface cisternae works as a sound reflector to protect DNA in nucleus against damages caused by higher sound pressures for resonance.

DOI： 10.23919/PIERS.2018.8597670

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：Institute of Electrical and Electronics Engineers Inc.  

Apart from medical/biological understandings and widely accepted V. Bekesy's traveling wave theory for human hearing system, this paper proposes a new sound detection theory based on extraordinary acoustic transmission. From engineering point of view, resonance on enlarged hair cell models including a set of membrane and pin-hole are demonstrated theoretically. This new idea can be applied to μm-scale super compact hair cells to account for mechanism of human hearing system.

DOI： 10.1109/MetaMaterials.2018.8534173

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

This paper proposes a spiral-shaped dispersive delay structure (Spiral-DDS) composed of vertically stacked spiral coils and vertical vias. This all-pass network architecture can produce a large group delay peak at a certain frequency in a few GHz range. Basic performance of the Spiral-DDS are studied theoretically, and the group delay with more than 6 ns was successfully generated by a compact multilayered architecture with dimensions of 6.0 x 6.0 x 1.18 mm (3). This paper also reports that the most of losses occurred in DDS comes from conductor loss, not from dielectric loss.

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Ultra-wideband(UWB)wirelesscommunicationsystems,utilizinga huge frequency range from 3.1GHz to 10.6GHz, are one of the key technologies to meet tremendous demands for up-coming high-speed wireless data communications. Thehardwareofsuchsystemsrequirestobemadeverycompactandhighly functional. In this paper, research history of our planar-type UWB band-pass filters composed of capacitively couped E-shaped electrodes is outlined first. After that, a super-compact multi-layered UWB bandpass filter is newly developed by using the E-shaped electrode architecture. The designed filter, with overall dimensions of 5.0 x5.0x0.95mm 3 ,hasaUWBpassbandfrom3.3GHzto10.7GHzinsimulation(a fractionalbandwidthof106%)andfrom3.5GHzto10.7GHzinexperiment(a fractionalbandwidthof100%).Inaddition,thefilterhasattractivetransmission zerosjustbelowandabovethepassband,whosecreationmechanismisstudied theoretically. Also, useful design procedure is introduced for this filter.

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Language：Japanese   Publisher：The Institute of Electrical Engineers of Japan  

A multi-layer composite right/left-handed (M-CRLH) transmission line (TL) was firstly proposed in 2004 as a new architecture to realize super-compact left-handed metamaterials, and the latest LTCC-based M-CRLH TL, with dimensions of 1.5mm×1.5mm×0.95mm, has a wide, flat, and low-insertion-loss passband with a fractional bandwidth of more than 130%. However, it still suffers from a deep transmission zero (TZ) yielded in a right-handed frequency region. This paper develops a new equivalent circuit model based on electromagnetic field simulations and explains creation mechanism of the TZ successfully by considering an inner-coupling in the unit-cell. Based on this argument, an ultra wideband TZ-free M-CRLH is designed and demonstrated.

DOI： 10.1541/ieejeiss.132.1310

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Other Link： https://jlc.jst.go.jp/DN/JALC/10007080844?from=CiNii

Language：English   Publishing type：Research paper (scientific journal)   Publisher：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC  

A compact multilayer non-commensurate C-section dispersive delay structure (DDS) is proposed for analog signal processing (ASP) applications. In contrast to a previously reported C-section DDS, which was uniplanar and used edge-coupled C-sections, this DDS is based on broadside-coupled C-sections, and hence achieves a much larger ratio of group delay swing to frequency bandwidth, leading to higher ASP resolution. Moreover, it is much more compact, while maintaining acceptable insertion loss. After a parametric characterization of a mono-block commensurate multilayer DDS, with varied strip widths, two multiblock non-commensurate DDSs with linear group delay slopes are demonstrated by full-wave simulation and experimental low-temperature co-fired ceramics results. The proposed DDS exhibits a significant footprint reduction factor of around 7 compared to its uniplanar edge-coupled counterpart.

DOI： 10.1109/LMWC.2011.2176476

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-BLACKWELL  

A compact ultra-widehand (UWB) bandpass filter using a multilayered structure is proposed. The proposed filter is composed of a pair of parallel plates, a meander line, and a thin conductor column that connects the parallel plates. The fabricated filter has a small size of 5 X 6 X 1.818 mm(3) that amounts to 0.19 lambda(g) x 0.22 lambda(g) x 0.07 lambda(g), where lambda(g) is the guided wavelength at the center frequency of the passband (6.95 GHz). CIWB bandpass characteristics from 1.9 to 12.0 GHz with two attenuation poles at 0.4 and 12.8 GHz were achieved. Experimental results are in good agreement with the numerical ones that are obtained from a simulation and an equivalent circuit. Flat group delay characteristics in the wide frequency range are also shown. (C) 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:557-559, 2011: View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.258

DOI： 10.1002/mop.25816

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Language：English   Publishing type：Research paper (international conference proceedings)  

An amplitude equalized C-section based all-pass dispersive delay structure (DDS) is proposed and experimentally demonstrated by cascading the DDS with a resistive transmission line network. Using such resistive networks, the frequency dependent dielectric and conductor losses of the transmission lines are equalized. This leads to a flat transmission response of the DDSs which is critical for efficient processing and detection of ultrafast time-domain signals using various analog signal processing (ASP) techniques. © 2011 IEEE.

DOI： 10.1109/TELSKS.2011.6143225

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This paper proposes a super-compact 0dB/3dB forward coupler composed of symmetrically installed two multi-layered (ML) composite right-/left-handed (CRLH) transmission lines (TLs). Each CRLH TL has double left-handed shunt-inductors to produce a large phase difference between even and odd modes, leading to significant size-reduction of forward couplers. Utilizing an inherent superior feature of ML CRLH TLs, that is, a large electrical length can be provided by an extremely short physical length, a 0dB/3dB forward coupler is designed at 3.0 GHz and 4.0 GHz respectively with very short coupling length of 1.57 mm. The dimensions of the coupler is 5.0 × 7.0 × 2.85 mm 3 with a dielectric material of εr=2.59. © 2010 EuMA.

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This paper proposes a super-compact dual-band Wilkinson power divider composed of two multi-layered (ML) composite right/left-handed (CRLH) transmission lines (TL). Theoretical analysis based on the finite element method shows that the divider with dimensions of 7.6 × 5.0 × 2.85 mm 3 has two operation bands from 3.7 GHz to 5.1 GHz in a left-handed branch and from 7.2 GHz to 8.0 GHz in a right-handed branch, with corresponding to the fractional bandwidth of 31.8% and 10.5%, respectively. Experimental verification is also carried out for the prototype model. This new architecture, incorporated with ML CRLH technique, is quite useful to realize high-functionality along with significant size-reduction. © 2010 EuMA.

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：Electromagnetics Academy  

A stepped impedance comb-line filter with defected ground structure (DGS) is proposed. The filter consists of two stepped impedance microstrip resonators. By using DGS, a coupling capacitor is inserted into the ground plane in order to build strong coupling locally along the resonators. The filtering characteristics were investigated through numerical simulations by means of FDTD method. Filtering characteristics that have attenuation poles at both sides of the passband were obtained. We discussed the input susceptances of even and odd modes.

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：Electromagnetics Academy  

In this study, we propose a compact ultra-wideband bandpass filter that is com- posed of a pair of defected parallel plates and a meander line. We analyzed the filtering char- acteristics by using a full-wave EM-simulator Ansoft HFSS Ver. 11 based on the finite element method. The results show that the wide passband from about 2.0 GHz to 11.0 GHz is obtained and attenuation poles are created at both sides of the passband. It is also shown that the flat group delay characteristics are achieved in the wide frequency range.

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

This paper newly proposes a super-compact planar ultra-wideband (UWB) bandpass filter composed of capacitor-loaded E-shaped electrodes. This capacitor supplies additional capacitance to the tightly-coupled electrodes, leading to relax the fabrication difficulties. By introducing the capacitor to the gap, response of the UWB passband is drastically improved. In the experiment, with a 0.5 pF capacitor, a clear UWB passband from 3.1 GHz to 11.4 GHz (FBW 114%) was obtained with small ripples of less than 0.5dB and minimum insertion loss of 0.4dB, which results show good agreement with the theory. Using this method, planar UWB filters can be made much more compact.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG  

This letter proposes a compact multi-layered bandpass filter exhibiting left-handed and right-handed behaviors in its passband. This filter has a greatly expanded passband from 1.61 GHz to 4.16 GHz (88.4% bandwidth), with a maximum ripple of 1.2 dB and well-suppressed out-of-passbands with transmission zeros at 1.15 GHz and 4.52 GHz. The physical mechanisms are studied with FEM-based full-wave simulations, equivalent circuit analysis and careful experiments.

DOI： 10.1093/ietele/e89-c.9.1348

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC  

A novel super-compact multilayered (NIL) composite-right/left-handed (CRLH). transmission line (TL) is proposed. This NIL architecture consists of the periodic repetition of pairs of U-shaped parallel plates connected to a ground enclosure by meander lines. The parallel plates provide the left-handed (LH) series capacitance, and the meander lines provide the LH shunt inductance, while the right-handed parasitic series inductance and shunt capacitance are generated by the metallic connections in the direction of propagation and by the voltage gradient from the TL to the ground enclosure, respectively. In contrast to previously reported planar LH or CRLH TLs, the NIL TL has its direction of propagation along the vertical direction, perpendicular to the plane of the substrates. This presents the distinct advantage that large electrical length cart be achieved over an extremely short TL length and small transverse footprint. The LH-range characteristics of the multilayer CRLH TL are analyzed by the finite-element method and finite-difference time-domain (FDTD) full-wave simulations. In addition, the CRLH equivalent-circuit model is applied to gain simple insight into the behavior of the structure. Finally, the theoretical results are confirmed by experiments using the initial prototype with the very small length (thickness) of 0.016 lambda(g) and footprint of 0.06 lambda(g) X 0.08 lambda(g) (lambda(g) = lambda(0)/root epsilon(r) = 235 mm at the center of the LH band, 0.4 GHz). The proposed miniaturized NIL line can find applications in bandpass filters, delay lines, and numerous phase-advance components. As an example of application, a 1-GHz/2-GHz diplexer, composed of two NIL CRLH TLs, is demonstrated. The NIL CRLH TL proposed here presents a great potential for the development of novel microwave components taking profit of new multilayer technologies such as low-temperature co-fired ceramic technology.

DOI： 10.1109/TMTT.2005.845189

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This paper proposes a new type of multi-stratified comb-line filters of narrow pass band utilizing conductor-backed coplanar waveguides. It is shown through numerical simulations by means of FD-TD method that the filtering characteristics can be controlled effectively by introducing a grounding conductor with a window between the coupled two resonators. It is demonstrated that, by changing the dimensions of the window on the grounding conductor, we can change, without affecting the odd mode, the input susceptance of the even mode independently and that we can adjust the frequency of attenuation pole. An interesting feature of this filter is that an additional window on the grounding conductor makes another attenuation pole appear around the passband. © 2003, The Institute of Electrical Engineers of Japan. All rights reserved.

DOI： 10.1541/ieejeiss.123.875

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC  

In this paper, a dual-plane comb-line filter having plural attenuation poles is proposed. We investigate the filtering characteristics from both experiments and numerical simulations by means of the finite-difference time-domain method. It is shown that this filter has attenuation poles just above, as well as below the passband and that intersections between the curves of input susceptance of the even and odd modes agree with the attenuation-pole frequencies. Furthermore, it is demonstrated that, by changing the position of the metal pin, which connects two resonators, we can change the input susceptance of the odd mode alone and, hence, regulate the attenuation-pole frequencies.

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In this paper, a harmonically controlled microstrip patch antenna having an electromagnetic band gap structure in the ground plane is studied. Basic behavior of this antenna is discussed through FDTD simulations and careful experiments. From these results, an impedance bandwidth of 14.7% (VSWR&lt
2.0) at the dominant, and the 2nd and 3rd harmonic free characteristic were obtained.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG  

This paper proposes a multisegment dielectric resonator (MSDR) placed on a slotline for millimeter-wave filter applications. The MSDR structure, including a rectangular dielectric lump and a thin low-dielectric insert, is quite useful for adjusting the coupling between the slotline mode and the resonant mode, leading to improve the filter performances. In addition, by tuning dimensions of the MSDR, a sharp and clear notch response can be designed in the transmission parameter. Me have demonstrated the filter characteristics both theoretically and experimentally, and showed the practical procedure for the design of MSDR filters.

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Language：English   Publishing type：Research paper (international conference proceedings)  

This paper proposes a novel multi-stage dual-plane comb-line filter having plural attenuation poles just below and above the passband. As this filter has such a structure that two quarter-wavelength step impedance resonators are placed face-to-face beyond the substrate on each filter block, the mutual coupling between adjacent blocks are small and the optimisation on each block can be done independently. High performance filters up to 4-stages are demonstrated both theoretically and experimentally.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC  

In this letter, the single microstrip patch antenna having two-dimensional photonic handgap (PBG) in the ground has been demonstrated experimentally, and the effectiveness of the PEG structure is discussed for the suppression of the resonance at the harmonic frequencies of the antenna. Experimental results indicate that the radiation patterns at the harmonic frequencies can be drastically diminished comparing with the normal microstrip patch antenna without the PEG structure, For instance, the radiation to the forward of the PEG antenna is suppressed at more than 15 dB at the third harmonic frequency.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IEEE  

The resonance at the harmonic frequency of the microstrip patch antenna can be suppressed by introducing the photonic band gap (PBG) structure in the ground plane. The harmonic radiation from the antenna drastically diminished as a result of the suppression. The phenomena was confirmed theoretically and experimentally.

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

This paper studies scattering characteristics of an optically controlled interdigital gap fabricated on the semiconductor microstrip line, and proposes the potential application of this gap to the microwave phase shifter with small variation in amplitude. Experiments have been carried out by making interdigital gap on the silicon chip and using the semiconductor laser diode.

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

This paper studies scattering characteristics of an optically controlled interdigital gap fabricated on the semiconductor microstrip line, and proposes the potential application of this gap to the microwave phase shifter with small variation in amplitude. Some experiments have been carried out to verify the theoretical predictions.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：John Wiley and Sons Inc.  

In this paper, the scattering characteristics of an optically controlled microstrip gap fabricated on a silicon substrate are analyzed theoretically using the (FD)2TD method, and the effects of the spot diameter of the laser beam, the location of illumination, and the plasma thickness on such characteristics are studied. The theoretical results show that twin peaks can be observed in the transmission coefficient (S21) by the use of a laser beam with a spot diameter smaller than the gap, and that nondispersive characteristics can be developed by a laser beam having a large spot diameter. Finally, the theoretical results are compared with measurements. © 1997 Scripta Technica, Inc.

DOI： 10.1002/ecjb.4420791202

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

Scattering parameters of an optically controlled microstrip gap fabricated on the semiconductor substrate have been analyzed theoretically using the frequency-dependent finite-difference time-domain method. The transmission characteristics of interest have been shown as a function of arbitrary position of laser spot around an air gap. The results have been demonstrated experimentally using microstrip line with silicon substrate and semiconductor laser. And, it is also reported that the high-powered illumination of laser spot develops non-dispersive characteristics of S21 for the wide frequency range.

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

We have demonstrated, in details, the scattering parameters of an optically controlled microstrip band pass filter fabricated on the semiconductor substrate. Frequency dependence on the transmission characteristics S21 are evaluated theoretically, when the plural number of laser spots illuminate on both air gaps on this filter. Further, the distribution of the standing waves occurred on the filter have been measured experimentally using the optical probing technique, and most sensitive position to be controlled optically is discussed.

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Language：English   Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG  

This letter proposes a microstrip band elimination filter having an optically controlled small gap on a resonant section for the shift of the eliminated frequency range using the semiconductor plasma. The basic characteristics of this filter are analyzed theoretically utilizing the (FD)(TD)-T-2 method.

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Language：English   Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG  

For the effective control of microwaves in the frequency domain, we propose a new method utilizing current distributions of standing waves on the terminated microstrip line. We analyzed a short ended microstrip line using the (FD)(TD)-T-2 method to indicate the effectiveness of our proposal. Further we proposed an optically controlled microstrip filter as an application of this method.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG  

In this letter, the effectiveness of the quasi-TEM approximation is studied for the microstrip line including optically induced semiconductor plasma region. This approximation is considered to be efficient under several restrictions such as the upper limit of the microwave frequency and the plasma density.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG  

For a method to control the microwave coupled lines with optically induced plasma effectively, we propose the selective mode-control method, which restricts controlled modes to a selected one. We analyzed the basic characteristics of coupled microstrip lines theoretically by using the spectral domain technique and indicated the effectiveness of this method with the aid of numerical results. Further, we designed an optically controlled change-over switch as an application of this method.

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Language：Japanese   Publisher：The Institute of Electronics, Information and Communication Engineers  

Negative impedance converters can provide a negative capacitance and a negative inductance. However, those non-Foster elements also include a resistance as a by-product. This resistance may absorb most of the input energy, leading to establishing a perfect matching in an appearance. This report evaluates both resistance and reactance of the non-Foster elements and proposes two strategies to reduce the resistance by 1) controlling the DC bias voltage and 2) utilizing a negative resistance of the NIC so as to cancel the undesired positive resistance of the non-Foster element.

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Language：Japanese   Publisher：The Institute of Electronics, Information and Communication Engineers  

Recently, negative impedance converters (NIC) have been widely focused due to their capability to produce non-Foster-type negative capacitance and inductance. In this technical report, Linvill's NIC is fabricated and demonstrated experimentally. As for a non-Foster-type impedance matching network for an electrically small monopole antenna, a wide band matching with -10 dB fractional bandwidth of 78.2 % for the center frequency of 386MHz was obtained. In addition, in the experiment of propagation between two monopole antennas, it was confirmed that the signal strength was enhanced around 200MHz by applying the non-Foster-type impedance matching network.

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Recently, negative impedance converter (NIC) technologies have been strongly focused on due to their capability of producing negative capacitances and negative inductances. Since the reactance slope versus frequency of such elements becomes negative against Foster's reactance theorem, they are called "non-Foster elements". In this report, firstly, recent trends on NIC researches are introduced shortly. After that, circuit parameters of the NIC circuit are optimized for a npn-type bipolar transistor NE85630, and then, negative capacitances, negative inductances, and opposite-signed reactances of a series LC resonant circuit are demonstrated by using the tuned NIC circuits. In addition, a new circuit topology such that a negative capacitance can be produced by using two negative resistances and several passive elements, whose idea was introduced at the conference IEEE AP-S 2013, is also examined to create the negative capacitances. In this study, two circuit simulators, LT-spice and Qcus, are utilized.

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Language：Japanese   Publisher：The Institute of Electronics, Information and Communication Engineers  

Negative impedance converters (NICs), which can produce negative capacitances or negative inductances, are quite attractive for their potential for developing a new type of circuits we have never designed so far. Since the circuits with sign-inversed reactances do not meet the Foster theorem, we call them "Non-Foster circuits" to distinguish them from the conventional passive circuits which meet the Foster theorem. This paper demonstrates accurate circuit analysis technique by using a commercial circuit simulator Ansys Designer and a full-wave EM simulator Ansys HFSS. Then, a super narrow-band band elimination filter is designed by introducing a NIC circuit.

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As one of approaches to realize left-handed metamaterials, a composite right/left-handed (CRLH) transmission line (TL) is well-know, and various kinds of applications have been proposed on a basis of the CRLH TL configuration. In this report, basic behaviour of a multi-layered (ML) CRLH TL is introduced together with its potential applications; a super-compact balun, a branch-line coupler, and a rat-race circuit. These applications are drastically miniaturized from its original size by engaging in the ML CRLH architecture.

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A grounded-patch embedded in a microstrip line substrate is attractive in respects of its small size and a deep and narrow notch response. In this report, to miniaturize this device, the influence of the metal pin connecting between the patch and the ground plane is studies theoretically by the FDTD method, and I obtained the results that the notch frequency could shift lower by using thinner metal pin. And also, similar results could be obtained by locating the metal pin not at the center but at the edge of the grounded-patch. Furthermore, by inserting a spiral coin in the middle of the metal pin, the notch frequency shifted drastically lower from 7.377GHz (standard model) to 2.044GHz. To confirm the theoretical predictions, several experiments have been carried out using an LTCC prototype model and good agreements could be obtained.

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Experiments have been carried out, from DC to X-band, about the microstrip fractal filter which has the fractal pattern based on the "Peano curve" on the surface of the microstrip. The result shows that this filter has very wide band-stop-characteristic of |S<21>|<-20dB at the frequency more than 2.5GHz. The cornnection point of microstrip lines to the fractal pattern can be selected comparatively freely without significant change of the characteristic of S<21> due to the symmetric pattern of the fractal. These experimental results are theoretically confirmed by the FDTD method.

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Event date： 2019.9

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Event date： 2019.8

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Event date： 2019.8

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Event date： 2019.7

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Event date： 2019.7

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Event date： 2019.7

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Event date： 2019.7

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Event date： 2019.3

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Event date： 2019.3

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Event date： 2018.11

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Event date： 2018.10

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Event date： 2018.10

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Event date： 2018.9

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Event date： 2018.8

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Event date： 2018.8

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Event date： 2018.8

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Event date： 2018.8

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Event date： 2018.7

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Event date： 2018.5

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Event date： 2017.12

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Event date： 2017.12

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Event date： 2017.11

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Event date： 2014.10

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Event date： 2014.9

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Event date： 2014.9

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Event date： 2014.8

Venue：Copenhagen, Denmark  

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Event date： 2014.7

Venue：Menphis (USA)  

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Event date： 2014.3

Venue：新潟大学  

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Event date： 2014.3

Venue：新潟大学  

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Event date： 2013.11

Venue：ソウル（韓国）  

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Event date： 2013.9

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Event date： 2013.8

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Event date： 2013.7

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Event date： 2013.7

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Event date： 2013.5

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Event date： 2013.3

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Event date： 2013.3

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Event date： 2012.12

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Event date： 2012.12

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Event date： 2012.12

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Event date： 2012.12

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Event date： 2012.12

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Event date： 2012.10

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Event date： 2012.9

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Event date： 2012.9

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Event date： 2012.9

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Event date： 2012.8

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Event date： 2012.7

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Event date： 2012.7

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Event date： 2012.6

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Event date： 2012.6

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Event date： 2012.6

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Event date： 2012.6

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Event date： 2012.6

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Event date： 2012.5

Recently, microwave technology has drawn considerable interests not only in wireless communication systems, but also in wireless power transmissions, chemical reactions, and heating systems. We are currently exploring the effects of microwave illumination upon plant growth. Different from conventional oil-based greenhouse heating systems, in which the heated air tends to stay in the ceiling area of the greenhouse, far from the plants to be heated, microwaves can directly heat the target plants by controlling radiation patterns of antenna arrays, leading to reduce the amount of energy consumption. This paper demonstrates that germination of cucumber seeds, placed under low-temperature environment, is promoted by a 2.45GHz, 50W microwave illumination.

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Event date： 2012.3

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Event date： 2012.3

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Event date： 2011.12

This paper proposes a multi-layered (ML) composite right/left-handed (CRLH) transmission line (TL) with a floating ground. Different from the conventional ML CRLH TLs, the proposed TL does not have any input/output ports and it works like a dielectric resonator by using an electromagnetic coupling with other circuits. Especially, since the physical parameters of the TL, a permittivity ε and a permeability μ, can be controlled by four CRLH equivalent circuit parameters such as a left-handed (LH) series capacitance CL, a LH shunt inductance LL and so on, materialistic design can be done for this TL. As an application example, a UWB bandpass filter having a in-band notch response was demonstrated theoretically.

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Event date： 2011.12

This paper presents a compact composite right/left-handed (CRLH) leaky wave antenna (LWA) composed of 2 × 2 coupled-mushrooms for broadband wireless communications. By optimizing gap widths between the mushrooms, the proposed antenna provides following attractive features; 1) a broadband performance from 6.4 GHz to 10.5 GHz is obtained, which fractional bandwidth corresponds to 49 %. 2) a high radiation efficiency of more than 98 % is attained through the entire operation band. 3) The radiation pattern of the antenna shows a weak directivity, which will be useful for high-speed data communications in mobile use. 4) Since the antenna has a planar structure based on a microstrip line configuration, the conventional print circuit board (PCB) facilities can be used for fabrication, leading to low cost antenna production. The overall dimension of the proposed antenna is 50 mm × 70 mm × 3.2 mm including the antenna substrate.

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Event date： 2011.10

In this paper, a 70.7 Ω quarter-length impedance transformer composed of a multi-layered composite right/left-handed transmission line is studied both theoretically and experimentally. In the theoretical analysis, fractional bandwidth of 49.3 % (fc=6.90 GHz) is obtained for connecting circuits with different impedances, 50 Ω and 100 Ω. A prototype model containing two impedance transformers (impedance transition of 50Ω -100Ω -50Ω) is fabricated, and it is confirmed that the measured results show good agreement with the theory. The overall dimensions of the proposed impedance transformer are 1.43 mm × 1.59 mm × 0.95 mm, which size is competitive to the recent super-compact devices used in mobile phones and other wireless communication terminals.

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Event date： 2011.10

This paper studies a multi-layered composite right/left-handed transmission line fabricated by using the latest low-temperature co-fired ceramic (LTCC) technology. Ultra wideband response from 3.1 GHz to 16.5 GHz in theory and 3.4 GHz to 18.0 GHz in experment were attained in a super-compact size of 1.5 × 1.5 × 0.95 mm3. As a specific feature of the LTCC-based design, a bandwidth of the left-handed branch is inherently large enough to cover a whole UWB band from 3.1 GHz to 10.6 GHz due to the small contribution of right-handed circuit parameters. A method to control the bandwidth with keeping a flat passband response is also developed for new type of wideband devices.

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Event date： 2011.10

An amplitude equalized C-section based all-pass dispersive delay structure (DDS) is proposed and experimentally demonstrated by cascading the DDS with a resistive transmission line network. Using such resistive networks, the frequency dependent dielectric and conductor losses of the transmission lines are equalized. This leads to a flat transmission response of the DDSs which is critical for efficient processing and detection of ultrafast time-domain signals using various analog signal processing (ASP) techniques.

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Event date： 2011.9

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Event date： 2011.9

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Event date： 2011.6

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Event date： 2011.6

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Event date： 2011.3

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Event date： 2011.3

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Event date： 2010.12

An ultra-wideband (UWB) band pass filter with a built-in notch filter is newly proposed. The filter is composed of a conventional multi-layered (ML) composite right-/left-handed (CRLH) transmission line and a super-compact notch filter configured by a ML CRLH unit cell. Two notches created by the notch filter are applied to improve a skirt characteristic of the UWB passband and to reduce interference from other existing wireless communication systems. Due to the structural compatibility of the notch filter, it can be fabricated just in the original CRLH UWB filter without any dimensional increase. In addition, flexible and wide-range tunability of the notches is also demonstrated.

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Event date： 2010.12

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Event date： 2010.12

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Event date： 2010.12

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Event date： 2010.9

This paper proposes a super-compact 0dB/3dB forward coupler composed of symmetrically installed two multi-layered (ML) composite right-/left-handed (CRLH) transmission lines (TLs). Each CRLH TL has double left-handed shunt-inductors to produce a large phase difference between even and odd modes, leading to significant size-reduction of forward couplers. Utilizing an inherent superior feature of ML CRLH TLs, that is, a large electrical length can be provided by an extremely short physical length, a 0dB/3dB forward coupler is designed at 3.0 GHz and 4.0 GHz respectively with very short coupling length of 1.57 mm. The dimensions of the coupler is 5.0 × 7.0 × 2.85 mm3 with a dielectric material of εr=2.59.

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Event date： 2010.9

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Event date： 2010.7

Venue：Chengdu, China  

This paper proposes three types of coupled multi-layer composite light-/left-handed transmission lines (TLs) fabricated in parallel beyond a small gap between them. By designing a left-handed shunt inductor appropriately, weakly-coupled TLs (Model 1), differential-mode TLs (Model 2), and tightly-coupled TLs (Model 3) can be realized. Basic behaviour of these TLs are studied theoretically based on even/odd-mode analysis.

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Event date： 2010.6

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Event date： 2010.6

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Event date： 2010.6

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Event date： 2010.6

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Event date： 2010.3

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Event date： 2010.3

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Event date： 2009.12

Venue：Singapore  

This paper proposes a super-compact wideband balun configured by a combination of a multi-layered (ML) composite right/left-handed (CRLH) transmission line (TL) and a conventional right-handed meander line. Quasi left-handed property of the ML CRLH TL is fully utilized for the phase design, leading to significant size reduction of the balun. The balun, with dimensions of 7.5 × 5.0 × 1.8 mm3, has been demonstrated theoretically in the frequency range from 5.0 GHz to 11 GHz (corresponding fractional bandwidth of 75 %). An amplitude imbalance was less than 2.0 dB (at 9.0 GHz) and a phase error was -7 to +5 degrees in this range.

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Event date： 2009.9 - 2009.10

In this paper, two types of super-compact couplers, a branch line coupler and a rat-race coupler, are newly designed by replacing their -90° or -270° right-handed transmission lines (TLs) with +90° or +270° multi-layered (ML) composite right/left-handed (CRLH) TLs. Since the recent ML CRLH TLs have a broadband left-handed (LH) response with a well-balanced CRLH condition, these couplers also work in a LH phase-advance region, leading to significant size reduction from their original size. The overall dimension of the branch line coupler is 7.5 × 7.5 × 1.8 mm3 @2.3 GHz and that of the rat-race circuit is 4.0 × 8.0 × 2.9 mm3 @3.0 GHz, respectively.

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Event date： 2009.9

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Event date： 2009.9

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Event date： 2009.9

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Event date： 2009.7

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Event date： 2009.6

Venue：Boston, NA, USA  

This paper newly proposes a balanced multilayered (ML) CRLH transmission line (TL) with defected parallel plates. This TL is super-compact in size (a body of the unit-cell is only 2.0 times 2.0 times 0.67 mm3) and has an ultra-wide passband from 1.8 GHz to 8.7 GHz which fractional bandwidth (FBW) corresponds to 131 % for the center frequency fc = 5.25 GHz) including a very wide left-handed (LH) region from 1.8 GHz to 6.8 GHz (116 % FBW of LH region for fc = 4.3 GHz). The well-balanced CRLH TL with quasi-LH properties is demonstrated for the first time both theoretically and experimentally. This ML architecture is quite useful for phase engineerings in the microwave devices using the phase-advanced properties in the ultra-wide LH region.

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Event date： 2009.6

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Event date： 2009.6

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Event date： 2009.3

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Event date： 2009.3

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Event date： 2009.3

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Event date： 2008.12

Venue：Macau  

In this paper, we propose a UWB bandpass filter composed of periodically-installed metallic posts in a rectangular waveguide, and study the basic behaviour both theoretically and experimentally. From the simulation, the wide passband from 5.95 GHz to 13.9 GHz and the well-suppressed out-of-passband were obtained, which results were verified experimentally. For the design of UWB response, we also study the important structural parameters of the filter.

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Event date： 2008.12

Venue：Macau  

This paper proposed a UWB bandpass filter composed of asymmetric E-shaped electrodes. By tuning the length of the electrodes' fingers, the locations of the transmission zeros at the higher out-of-passband were synthesized separately and widely-suppressed out-of-passband response was realized. Compared with the symmetric model shown in Fig. 1 (a), the dimensions of the new model was 5.1 mm by 5.1 m by 0.8 mm, and the great advantage ldquosuper-compactnessrdquo of the original filter was still maintained in the proposed filter.

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Event date： 2008.12

Venue：龍谷大学  

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Event date： 2008.12

Venue：龍谷大学  

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Event date： 2008.10

Venue：Amsterdam  

This paper newly proposes a super-compact planar ultra-wideband (UWB) bandpass filter composed of capacitor-loaded E-shaped electrodes. This capacitor supplies additional capacitance to the tightly-coupled electrodes, leading to relax the fabrication difficulties. By introducing the capacitor to the gap, response of the UWB passband is drastically improved. In the experiment, with a 0.5 pF capacitor, a clear UWB passband from 3.1 GHz to 11.4 GHz (FBW 114%) was obtained with small ripples of less than 0.5 dB and minimum insertion loss of 0.4 dB, which results show good agreement with the theory. Using this method, planar UWB filters can be made much more compact

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Event date： 2008.10

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Event date： 2008.10

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Event date： 2008.10

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Event date： 2008.10

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Event date： 2008.10

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Event date： 2008.9

Venue：Shanghai  

This paper studies multi-layered composite right-/left-handed transmission lines (ML CRLH TL). To realize wideband response from left-handed passband to right-hand passband without band gaps and other undesired parasitic resonances, a balanced ML CRLH TL with defected parallel plates is newly proposed and demonstrated theoretically by using FEM-based EM simulator. A wide passband from 2.0 GHz to 9.5 GHz was attained with balanced condition, which is useful for UWB applications.

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Event date： 2008.9

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Event date： 2008.3

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Event date： 2007.12

Venue：Bankok, Thai  

We have reported a compact planar-type UWB bandpass filter with tightly coupled E-shaped electrodes by Y. Horii (2007). In this paper, a useful and practical design procedure for this filter is developed, and explained in details with full-wave simulations. In addition, the resulting model designed by the introduced procedure is demonstrated experimentally to confirm the theoretical predictions. Furthermore, the design procedure is applied to several models with different substrate parameters, and a super-compact filter is designed on the substrate with the relative permittivity of 10 and thickness of 0.5 mm, whose dimensions, 2.7 mm x 2.01 mm x 0.5 mm (filter body), correspond to 24.4 % size reduction from the initial model reported in Ref [1].

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Event date： 2007.12

Venue：Bankok, Thai  

This paper proposes a compact multi-layered ultra- wideband (UWB) bandpass filter including a built-in band- rejection filter, for preventing the UWB communications from interfering with already-existing wireless communication systems. The band-rejection response obtained can be controlled flexibly by changing a coupling capacitance to the closest parallel metal plate or to the ground enclosure. In the finite element analysis and equivalent circuit simulation, a UWB performance of around 90% relative bandwidth and a widely-controllable band-rejection response were obtained. Also, experimental results show good agreement with those theory. This compact filter, originally designed based on the heft-handed composite right-/left-handed (CRLH) transmission line theory [1, 2], has a perfectly-shielded structure, a moderate group delay and excellent out-of-passband characteristics.

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Event date： 2007.12

Venue：Bangkok  

We have reported a compact planar-type UWB bandpass filter with tightly coupled E-shaped electrodes by Y. Horii (2007). In this paper, a useful and practical design procedure for this filter is developed, and explained in details with full-wave simulations. In addition, the resulting model designed by the introduced procedure is demonstrated experimentally to confirm the theoretical predictions. Furthermore, the design procedure is applied to several models with different substrate parameters, and a super-compact filter is designed on the substrate with the relative permittivity of 10 and thickness of 0.5 mm, whose dimensions, 2.7 mm x 2.01 mm x 0.5 mm (filter body), correspond to 24.4 % size reduction from the initial model reported in Ref [1].

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Event date： 2007.10

Venue：Munich  

This paper proposes a new planar-type ultra- wideband (UWB) bandpass filter (BPF), and the basic behaviour of the filter is studied theoretically and experimentally. The UWB BPF, having a widely spread passband from 3.7 GHz to 10.4 GHz (theory), mild group delay of about 0.2 ns (experiment), and two convenient attenuation poles around the passband, has been developed in a very compact size (10 mm x 15 mm x 0.8 mm). This filter has a great potential for small UWB devices used in wireless USB applications and high-speed personal data communication systems.

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Event date： 2007.10

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Event date： 2007.10

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Event date： 2007.10

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Event date： 2007.3

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Event date： 2007.3

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Event date： 2006.8

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Event date： 2006.7

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Event date： 2006.6

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Event date： 2006.6

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Event date： 2006.6

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Event date： 2005.12

PrintRequest Permissions This paper proposes a band elimination filter composed of a mushroom resonator embedded in a microstrip line substrate. In the finite-difference time-domain (FDTD) simulation, a small grounded-pad with 0.074λ0 × 0.074λ0 creates a deep notch response of -37.7 dB at 7.38 GHz, which prediction is experimentally confirmed by using a low temperature co-fired ceramic (LTCC) prototype model. Mechanism of creating the notch response is fully explained by an equivalent circuit model, and an accurate design procedure is developed. This filter can be used as a compact spectrum synthesizer for improving an original frequency response of microwave components by fabricating this filter onto a same platform with those components.

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Event date： 2005.12

This paper proposes a novel ultra-wideband (UWB) bandpass filter (BPF) with a shielded multilayered (ML) structure. Compared with recently proposed planar UWB BPFs based on a microstrip line configuration, this filter can be made more compact and can reduce the interference to other circuit components. We have studied scattering characteristics of the filter by a finite element method (FEM), an equivalent circuit analysis and experiments. In the FEM analysis, this filter shows a UWB performance from 1.61 GHz to 4.11 GHz, which bandwidth corresponds to RBW-3dB = 87.4%. In this passband, the maximum ripple is 0.86 dB and the minimum insertion loss is 0.11 dB. These theoretical predictions show good agreement with the experimental results. Further, a measured group delay is moderate around the center passband with a typical value of 0.4 ns. An equivalent circuit model is also developed to gain a useful insight into the filter mechanism.

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Event date： 2005.12

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Event date： 2005.11

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Event date： 2005.11

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Event date： 2005.10

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Event date： 2005.9

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Event date： 2005.9

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Event date： 2005.6

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Event date： 2005.3

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Event date： 2004.12

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Event date： 2004.10

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Event date： 2004.9

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Event date： 2004.6

This paper proposes a band pass filter having plural transmission zeros by using a grounded capacitive-inductive-capacitive configuration, and studies the basic behavior of the filter both theoretically and experimentally. This filter with dimensions 12 × 12 × 1.588 mm3 (0.027 λ0 × 0.027 λ0 × 0.04 λ0) shows 4.61% passband width around 0.686 GHz in theory, and the prediction is confirmed experimentally with reasonable errors. This filter configuration is suitable for an LTCC multi-layered technology.

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Event date： 2004.6

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Event date： 2004.5

In order to achieve a safe automotive society, it is necessary to develop an on-board intelligent system with inter-vehicle communications (IVC). We want to avoid vehicle collisions under most situations, such as intersections, highways, and blind corners, by using IVC technology through wireless ad hoc networks. The paper describes a vehicular collision avoidance support system (VCASS), and shows its performance by various experiments with two real vehicles. We have installed personal computers, telecommunication equipment, and GPS in the vehicles. A vehicle exchanges location information and velocity vectors with the other by a UDP broadcast, and calculates the relative position/speed. Vehicles warn the drivers of the possibility of collision. We verify the validity and effectiveness of VCASS by experiments.

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Event date： 2004.3

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Event date： 2004.3

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Event date： 2003.11

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Event date： 2003.11

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Event date： 2003.10

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Event date： 2003.10

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Event date： 2003.9

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Event date： 2003.9

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Event date： 2003.9

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Event date： 2003.9

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Event date： 2003.8

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Event date： 2003.6

Venue：Columbus, OH, USA  

This paper proposes a new approach to suppress the harmonic radiation from a microstrip patch antenna by embedding several grounded-pads in an antenna substrate. The grounded-pad is composed of a rectangular metal pad and a thin metal wire connecting between the pad and the ground plane. Even though the pad is very small in size, it works as a deep and narrow band elimination filter. The basic behavior of this pad is studied theoretically by the FDTD method. Finally, several grounded-pads are embedded in the substrate of a microstrip patch antenna to suppress harmonic resonances.

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Event date： 2003.6

Venue：Clombus, Ohio, USA  

This paper proposes a new approach to reduce the size of the patch antenna by embedding a 2D grounded-pad array in an antenna substrate. Periodically installed grounded-pads are expected to exhibit slow-wave effects. First of all, a microstrip delay line having a 1D grounded-pad array in its substrate is demonstrated theoretically by the conventional FDTD method, and the slow-wave effect is discussed in section 2. Next, a 2D grounded-pad array is applied to a microstrip patch antenna to reduce the size of the antenna, and experimental results are shown in section 3 together with the theoretical ones. In the experiment using a prototype model, an LTCC substrate, which is suitable for multi-layer structures, was adopted.

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Event date： 2002.6

Venue：San Antonio, TX, USA  

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Event date： 2002.3

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Event date： 2002.3

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Event date： 2002.1

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Event date： 2002.1

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Event date： 2001.12

This paper proposes a novel multi-stage dual-plane comb-line filter having plural attenuation poles just below and above the passband. As this filter has such a structure such that two quarter-wavelength step impedance resonators are placed face-to-face beyond the substrate on each filter block, the mutual coupling between adjacent blocks are small and the optimisation on each block can be done independently. High performance filters up to 4-stages are demonstrated both theoretically and experimentally.

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Event date： 2001.11

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Event date： 2001.11

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Event date： 2001.11

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Event date： 2001.11

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Event date： 2001.11

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Event date： 2001.11

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Event date： 2001.9

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Event date： 2001.9

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Event date： 2001.7

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Event date： 2001.5

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Event date： 2001.3

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Event date： 2001.1

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Event date： 2000.12

Venue：Sydney, NSW  

As a millimeter-wave application, we have demonstrated a novel dielectric resonator placed on the slotline both theoretically and experimentally. And a sharp notch response of more that -30 dB could be obtained. Proposed slot line filter, having the simple structure and small in size, is useful for millimeter-wave signal processing

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Event date： 2000.12

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Event date： 2000.11

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Event date： 2000.10

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Event date： 2000.9

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Event date： 2000.9

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Event date： 2000.9

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Event date： 2000.7

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Event date： 2000.7

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Event date： 2000.5

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Event date： 2000.4

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Event date： 1999.11 - 1999.12

As a new skill to suppress the harmonic radiation from the antenna we introduce the 2-dimensional photonic band gap structure (PBG) to the ground plane of the microstrip patch antenna. Theoretical and experimental results indicate that the resonance at 1st and 2 nd harmonics can be removed perfectly and the radiation is suppressed at more than 15 dB.

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Event date： 1999

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Event date： 1998

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Event date： 1998

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Event date： 1998

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Event date： 1998

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Event date： 1997.12

This paper studies scattering characteristics of an optically controlled interdigital gap fabricated on the semiconductor microstrip line, and proposes the potential application of this gap to the microwave phase shifter with small variation in amplitude. Some experiments have been carried out to verify the theoretical predictions.

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Event date： 1997.6

Venue：Denver, CO, USA  

This paper studies scattering characteristics of an optically controlled interdigital gap fabricated on the semiconductor microstrip line, and proposes the potential application of this gap to the microwave phase shifter with small variation in amplitude. Experiments have been carried out by making interdigital gap on the silicon chip and using the semiconductor laser diode.

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Event date： 1997

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Event date： 1997

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Event date： 1997

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Event date： 1997

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Event date： 1996.12

Venue：Kyoto, Japan  

We have demonstrated, in detail, the scattering parameters of an optically controlled microstrip band pass filter fabricated on the semiconductor substrate. Frequency dependence on the transmission characteristics S/sub 21/ are evaluated theoretically, when the plural number of laser spots illuminated both air gaps on this filter. Further, the distribution of the standing waves occurring on the filter have been measured experimentally using the optical probing technique, and the most sensitive position to be controlled optically is discussed.

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Event date： 1996.6

Venue：San Fransisco, CA, USA  

Scattering parameters of an optically controlled microstrip gap fabricated on the semiconductor substrate have been analyzed theoretically using the frequency-dependent finite-difference time-domain method. The transmission characteristics of interest have been shown as a function of arbitrary position of laser spot around an air gap. The results have been demonstrated experimentally using microstrip line with silicon substrate and semiconductor laser. And, it is also reported that the high-powered illumination of laser spot develops non-dispersive characteristics of S/sub 21/ for the wide frequency range.

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Event date： 1996.6

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Event date： 1996

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Event date： 1995

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Event date： 1995

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Event date： 1992

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