Takenori Yasuzumi

A Thin Wave Absorber Using Closely Placed Divided Conductive Film and Resistive Film

In this letter, the design for a thin wave absorber using an admittance sheet composed of closely placed resistive film and divided conductive film is studied. The admittance of the sheet has frequency dependence because of the mutual influence between the films. The matching frequency of the absorber depends on its thickness (<; λ/4) and susceptance of the sheet. Likewise, the reflection value at the frequency depends on conductance of the sheet. The effects of the parameters of the resistive film and the divided conductive film on the admittance characteristics of the sheet were investigated. Then, the design procedure for the absorber was discussed. The tendency of measured reflection characteristics agreed well with the simulated ones.

Polarization tracking phased array antenna with cross dipole antenna

In this paper, a phased array antenna (PAA) using crossed dipole antenna elements is examined. A partially driven array technique is used for the array antenna. From the analyzed results, it is shown that the element antenna has conical radiation pattern. Using the element antenna, the beam scanning characteristics of the PAA is investigated. It is found that this array antenna can scan the beam in all directions successfully. Therefore, this PAA can be applicable to the mobile station antenna of satellite communications.

A compact LPF with broad stopband characteristics using hairpin structure and chip-capacitor

A compact microstrip lowpass filter is proposed in this paper. The LPF consists of hairpin type inductor lines as quasi-lumped elements, coupled lines and a chip-capacitor. Firstly, using the equivalent circuit, the transmission zero frequencies are investigated. As a results, the proposed filter has two attenuation poles at a stopband. Then, cascaded LPF is cross examined with the simulated and experimental results. The measured results show that the experimental LPF has sharp attenuation slope at the cut-off frequency and wide rejection characteristics.

Ultra-wideband bandpass filter using matching-lines and interdigital filter with close-coupled resonators

This paper presents an ultra-wideband bandpass filter (UWB BPF) using quarter-wavelength inverter-lines at both sides of a three-pole interdigital filter. The relations between the impedances of the inverter-line with the load and those of the interdigital filter connected to the inverter-line were studied. From these, the design procedures for the impedance matching at the UWB passband edges were shown. Then the designed BPF from the above results showed that the bandwidth was 24% wider than that of the sole interdigital filter by additional two conjugate matching poles. The fabricated BPF achieved the performances of the required passband by the five matching poles.

A phased array antenna using cross dipole antenna for mobile satellite communications

In this paper, we propose a phased array antenna which consists of crossed dipole antenna with a reflector as an element antenna. The element antenna is designed by optimizing its parameters. The main and cross polarization characteristics of the right and left side beam scanning of the fabricated 19-element array antenna is measured. Next, the experimental results of the beam scanning characteristics is discussed. It is shown that the measured results is effective to a satellite communications mobile station.

A study on phased array antenna using MSA composed by 3-patches

In this paper, a new type of phased array antenna using bi-layered microstrip antenna (MSA) composed by 3-patch element is proposed. An element antenna of the array has conical radiation pattern at E- and H-plane. Firstly, the bi-layered MSA of conical radiation pattern is examined analytically by an electromagnetic field simulator. It is shown that desirable radiation patterns are obtained. Then, using the element antenna, the beam scanning characteristics of a 4 × 4-element array antenna is investigated. As a result, the proposed antenna is promising in use of mobile satellite communications.

Positional dependence on primary radiator of metal plate lens antenna

In this paper, positional dependence on primary radiator of metal plate lens antenna is studied. A focal distance of the lens was derived to be 129 cm by using geometrical optics. By arranging the lens in front of a horn antenna, the gain was improved from 18 dBi to 26 dBi. Then the antenna characteristics were evaluated when the distance between the antenna and the lens changes. As the results, the changes of the antenna gain were within 1 dB with the reduction of the distance of 10 λ0. The phase and field intensity of electromagnetic wave are evaluated to clarify the foundation of given characteristics.

A study on dipole antenna having conical radiation pattern with EBG as a reflector

In this study, to achieve low profile dipole antenna having conical radiation pattern for satellite communications, we investigate the dipole antenna with EBG as a reflector. Firstly, the EBG structure is designed and simulated at 12.5 GHz. Next, radiation patterns of the dipole antenna arranged above the PEC and EBG are investigated and compared. Finally, mutual coupling effect of 2-element array antenna, which is with the PEC or EBG as a reflector is examined.

An experimental study on thin absorber using lossy sheet and periodic metal films

In this paper, an one-layered type thin wave absorber consisting of periodic metal films and a lossy sheet is investigated. Firstly, surface impedance that satisfies a matching condition of lossless and lossy materials is calculated as a function of a complex relative permittivity. Next, the dielectric constants of the loss material are measured. Moreover, the absorption characteristics of the wave absorber are analytically examined by an electromagnetic field simulator. In addition, the wave absorber is fabricated and measured. As the results, it is shown that the tendency of the absorption characteristics is similar to simulated one.

A study on the UWB BPF using the hairpin-type LPF and the Parallel-coupled Lines

A compact ultra wide-band bandpass filter is proposed in this paper. The BPF consists of a hairpin-type LPF with a chip capacitor and a HPF using parallel-coupled lines. Firstly, the circuit model of LPF is investigated. Next, the characteristics of the HPF is also examined, and the results show the broad bandpass characteristics. Then the performances of UWB BPF composed of the LPF and the HPF are simulated and measured. As the results, the filter show the performance close to the FCC-Full band. In addition, UWB BPF using high dielectric rod by LTCC technology is simulated which has the similar performance without the chip capacitor.