Yasushi Horii

Harmonic control by photonic bandgap on microstrip patch antenna

In this work, the single microstrip patch antenna having two-dimensional photonic bandgap (PBG) in the ground has been demonstrated experimentally, and the effectiveness of the PBG 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 PBG structure. For instance, the radiation to the forward of the PBG antenna is suppressed at more than 15 dB at the third harmonic frequency.

Multilayer Broadside-Coupled Dispersive Delay Structures for Analog Signal Processing

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.

Development of vehicular-collision avoidance support system by inter-vehicle communications - VCASS

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.

A super-compact balanced multi-layered CRLH transmission line with wideband LH properties for microwave phase engineerings

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 × 2.0 × 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.

A compact planar ultra-wideband bandpass filter composed of coupled e-shaped electrodes

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.

A dual-plane comb-line filter having plural attenuation poles

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.

Super-Compact Planar Ultra-Wideband (UWB) Bandpass Filter Composed of Capacitor-Loaded E-shaped Electrodes

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.

A compact band elimination filter composed of a mushroom resonator embedded in a microstrip line substrate

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 0.074/spl lambda//sub 0/ /spl times/ 0.074/spl lambda//sub 0/ 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.

A compact multilayered bandpass filter with transmission zeros for UWB applications

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/sub -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.

Amplitude equalized transmission line dispersive delay structure for analog signal processing

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.