Toru Fukasawa

Study on circularly polarized cavity antenna fed by L-shaped probes

A circularly polarized cavity antenna that is fed by L-shaped probes is proposed in this paper. This antenna has a simple configuration and good connectivity with a feed circuit. Wideband impedance matching is achieved by using the vertical arm of the L-shaped probe located near the side of the cavity as an impedance transformer, thus eliminating the need for other impedance matching circuits. The effectiveness of the proposed antenna has been confirmed experimentally.

Demonstration of a highly efficient seawater antenna

Seawater can be used as an antenna element because of its relatively high electrical conductivity. It can operate as a monopole antenna by squirting the seawater into the air and feeding. Moreover it has the advantages of being dynamic and reconfigurable. This paper reports the design of an efficient feeding structure for a seawater antenna. The viability of this seawater antenna is confirmed by a demonstration of receiving digital terrestrial broadcasts.

A feed circuit-integrated planar array antenna using anisotropic conductive paste

A multifunctional antenna typified by an array antenna is composed of each substrate suitable to an antenna and a feed circuit. A multifunctional antenna has a challenge in thickness and weight because it uses the interconnecting structures as the connectors and jigs to connect these substrates to each other. Therefore, in this paper, in order to develop a thin and lightweight multifunctional antenna, a feed circuit-integrated array antenna using an anisotropic conductive paste is designed and considered in the numerical calculation and measurement as fundamental investigation.

Miniaturized broadband circularly polarized antenna allocated in a rotational symmetry

This paper proposes a broadband circularly polarized antenna that is composed of inverted F and L antennas on the ground plane, and is allocated in a rotational symmetry. The height and diameter of our proposed antenna is respectively 0.10λ<inf>0</inf> and 0.33λ<inf>0</inf>. The relative bandwidth satisfied with VSWR<3 in each band is 10.7% and 6.9%.

Development of active phased array antenna for high SHF wideband massive MIMO in 5G

In the 5th generation mobile communication system, large system capacity, low latency and massive connection will be provided for novel and various applications. In order to realize these features, we are developing high SHF band massive-MIMO system which can secure wide system bandwidth and high spectral efficiency. Especially, the combination of analog beamforming (APAA: Active Phased Array Antenna) and digital MIMO signal processing for the multi-beam multiplexing is one of the promising approaches for reducing the complexity and power consumption. In this paper, hybrid beamforming configuration for high SHF band massive-MIMO system will be shown. Additionally the developed results of fundamental technologies such as array antenna panel and RF components are presented.

Side lobe suppression for air-coupled ultrasonic transducer with parabolic horn

Air-coupled ultrasonic transducers are widely used in object detection devices. In general, the detection range of an object detection device using an air-coupled ultrasonic transducer is short because the radiation efficiency of air-coupled ultrasonic transducers is very low. It is necessary to extend the detection range of air-coupled ultrasonic transducers for use in object detection devices such as collision avoidance systems for automobiles. This paper presents a theoretical and experimental study of improving the radiation efficiency of an air-coupled ultrasonic transducer using a horn in a collision avoidance system. A method for suppressing the side lobe caused by attaching the horn to decrease detection errors in the collision avoidance system is also proposed.

Design and evaluation of HF/UHF dual-band RFID tag utilizing HF-coil as UHF antenna conductor

The demand for RFID tags that can be read by both HF and UHF RFID systems has been rapidly increasing. In this paper, we propose a novel HF/UHF dual-band tag antenna configuration that utilizes an HF coil conductor positively as a UHF antenna conductor. In order to control UHF current flowing on the coil and to achieve high radiation efficiency, the coil windings are coupled capacitively. The inductively coupled feed technique is adopted to obtain wider impedance bandwidth. It is shown by numerical electro-magnetic simulation that the fractional bandwidth of the actual gain of more than 1 dBi and 0 dBi are approximately 11% and 16%, respectively. The readable ranges of the prototype tag are 8-m and more than 10-cm in the UHF and HF, respectively.

Comparative study of IDR and BiCG variant methods in numerical analysis based on method of moments

In this study, we investigate the performance of the variants of the induced dimension reduction (IDR) in large-scale electromagnetic scattering problems. Comparative numerical experiments, using IDR(s), GIDR(s, L), and ML(s)BiCGSTAB reveal that GIDR(s, L) shows the fastest convergence property among the three IDR variants. In a numerical experiment with a practical radiation problem, GIDR(s, L) with an s value of around 15 shows the best performance with respect to the balance between the convergence property and the tolerance to the spurious convergence.

Convergence property of IDR variant methods in the integral equation analysis of electromagnetic scattering problems

In this study, we investigate the performance of the variants of the induced dimension reduction (IDR) in large-scale electromagnetic scattering problems. We also focus on the tolerance to the so-call spurious convergence and convergence property of the IDR variant methods. Comparative numerical experiments, using IDR(s), Bi-IDR(s), and GIDR(s, L), reveal that GIDR(s, L) with L F 2 or 4 and an s value of around 15 shows the best performance with respect to the balance between the convergence property and the tolerance to the spurious convergence for problems with several levels of geometry complexity.

Convergence property of IDR variant methods implemented with method of moments

In this study, we investigate the performance of the variants of the induced dimension reduction (IDR) in large-scale electromagnetic scattering problems. Comparative numerical experiments, using IDR(s), GIDR(s, L), and ML(s)BiCGSTAB reveal that GIDR(s, L) shows the fastest convergence property among the three IDR variants. In a numerical experiment with a practical radiation problem, GIDR(s, L) with an s value of around 15 shows the best performance with respect to the balance between the convergence property and the tolerance to the spurious convergence.