Yoshiyuki Fujino

Polarimetric calibration of the SIR-C C-band channel using active radar calibrators and polarization selective dihedrals

A polarimetric calibration experiment of Shuttle Imaging Radar C (SIR-C) is carried out using several different calibration targets. These are C-band polarimetric active radar calibrators (PARCs), polarization selective dihedrals (PSDs), 22.5/spl deg/ rotated dihedrals, and a trihedral. A novel polarimetric calibration algorithm is proposed that combines existing algorithms and uses one PARC and two PSDs. An error evaluation example is shown to estimate the typical hardware error value of the calibration targets allowable for a given calibration error. The novel algorithm gives polarimetric calibration results comparable to those obtained using the existing algorithm for three PARCs. Since PSDs work at frequencies lower than design frequency, and hence can be commonly used at multiple frequency bands, the simple addition of just one more frequency band PARC allows polarimetric calibration of a dual-frequency polarimetric synthetic aperture radar (SAR) by means of the proposed algorithm.

5.8-GHz planar hybrid rectenna for wireless powered applications

This paper presents a high-efficiency low-reradiation planar rectifying antenna (rectenna). The rectenna is composed of a high-gain cavity-backed circular patch antenna using novel coplanar feeding structure and a low-profile microstrip rectifying circuit. The cavity-backed antenna achieved the gain of 9.17dBi and the -20dB return loss bandwidth of approximately 1.4%. The rectifying circuit has a harmonics filter that suppresses the reradiated harmonics under -59 dBc. The RF-to-dc conversion efficiency of the rectenna element was measured as 71.4% with a 266mW input power. Over 13W DC output power was demonstrated using the 52- element triangular array.

Satellite Terrestrial Integrated mobile Communication System as a disaster countermeasure

Creating a safer society requires communication methods available during disasters. This need has prompted the start of research and development to build a mobile satellite communication system for the satellite terrestrial common terminal. The system is called STICS (Satellite/Terrestrial Integrated mobile Communication System). A dual communication function that can connect to both the terrestrial system and the satellite system is formed by using a common terminal with a portable, handheld shape. This paper discusses the research and development and the current status of STICS.

S-band active phased array antenna with analog phase shifters using double-balanced mixers for mobile SATCOM vehicles

We propose an S-band active phased array antenna (APAA) with analog phase shifters (PSs) that use double-balanced mixers (DBMs). The quadrature phase shift keying modulator integrated circuits (ICs) used as the phase shifters can control both the amplitude and phase of the input signal continuously and independently by using the control voltages. The phase and amplitude errors during phase rotation were 0.5/spl deg/ rms (max=1.7/spl deg/) and 0.3 dB rms (max=0.7 dB), respectively. The range in which the amplitude could be linearly changed was 7 dB. The proposed antenna exhibited sufficient performance for mobile vehicles to handle satellite communications: beam-pointing resolution of 0.04/spl deg/, beam-pointing accuracy in the null pointing of 0.4/spl deg/ rms, and sidelobe suppression with an amplitude taper achieved by setting the amplitude of the PS using two DBMs. Comparison between the analog PS and a reflection-type four-bit digital PS showed that although the analog one is unsuitable for use in a passive PAA, it is suitable for use in an APAA.

Variable spot scanning antenna using optically controlled beam forming network

An Optically controlled beam forming network has been developed, which has capacity of steering 2 beams and exciting 64 antenna elements. Using it, beam steering and beam width control is possible in parallel.

Development of A C band rectenna for microwave power transmission toward a space robot

Abstract For the miniaturization of microwave power transmission systems, a rectenna with a higher frequency than a conventional S band rectenna is desirable. In this paper, we present a C band rectenna element operating at the 5.8 GHz ISM frequency, and show its application in a multi-joint robot on a space platform.

Spatial light modulator based optically controlled beamformer for variable multiple-spot beam antenna

We propose and demonstrate an optically controlled multiple-beam phased array antenna employing spatial light modulator. Developed prototype of the optical beamformer enables control multiple-beam direction and width; we demonstrated beamforming operation at 18 GHz. Furthermore, we have performed the communication test such as the bit error ratio (BER) test, data rate of 622 Mbps and 1244 Mbps in the digital communication link. We have confirmed that this optical beamformer had no serious effect for BER performance.

On Interference Level in Satellite Uplink for Satellite/ Terrestrial Integrated Mobile Communication System

This paper describes a fundamental analysis on the interference level in Satellite/Terrestrial Integrated Mobile Communication System (STICS). STICS is a research and development project in Japan which provides both satellite and terrestrial communications systems to dual-mode terminals. When the Mobile Satellite Service (MSS) frequency band is shared by the terrestrial and the satellite system, inter-system interference occurs. In this study, we focus on the interference level in satellite uplink (satellite reception link) in which the interference level depends on the number of terrestrial service users and thus the permissible interference level in this link determines the user capacity of the terrestrial system. Interference estimation in the satellite uplink has been carried out for two categories; the interference caused by terrestrial system uplinks and satellite system uplinks. A newly developed interference estimation simulator based on signal power calculation is utilized for the estimation. The MSS frequency band is reused by seven frequency bands. Japanese main island with part of Exclusive Economic Zone (EEZ) is covered by twentythree satellite spot-beams. Terminals and base stations using terrestrial link are located in the main island under uniform distribution. Spatial guard-band concept is introduced to reduce the interference level in satellite uplink. The effect of the spatial guard-band is verified by evaluating the relationship among spatial guard-band level, carrier to interference level, and terrestrial user capacity. A coverage rate of the terrestrial system as a function of spatial guard-band is also evaluated. Finally, a co-channel interference level caused by the uplinks from satellite link users in other satellite cells is evaluated.

A Study of Large Reflector Antenna mounted on Communication Satellite for Satellite /Terrestrial Mobile Communication System

We have been researching and developing the STICS (Satellite / Terrestrial Integrated Mobile Communication System). For this system, a large satellite antenna technology is very important and we have been studying the antenna with approximately 30m aperture size. This antenna consists of the deployable reflector and the phased array feed and performs the multi beam formation. Number of array elements and beams are about 100 respectively. But the high accuracy of beam control, as pointing, beam shape and side lobe level, will be required because the beam width is very narrow as about 200km at S band. Digital beam former and digital channelizer (DBF/DC) was developed for this system. DBF/DC has excellent flexibility for beam shaping function. In this paper, we summarize study, discussion and experiment of large reflector antenna for STICS, and describe technical issue of this antenna.

Waveguide fed short backfire antennas with parasitic wires

High gain microstrip patch array antennas have the advantages of low weight, low profile and low cost for mass production over traditional aperture antennas for applications requiring around 10% bandwidth, such as terrestrial point-to-point or as feeds to mechanically scanned reflectors for aircraft. However, ohmic losses in the microstripline feed network of a large scale microstrip patch array antenna can reach 30dB/m at mm-wave band which limits the gain and increases the noise temperature [1]. The use of waveguide for the long trunk lines within a feednetwork avoids the line loss problem. However, a waveguide fed antenna more readily connects to a waveguide network than a 4x4 microstrip patch array antenna. Consequently, a waveguide fed antenna with shorter length than a horn was sort which could connect to a parallel feed rectangular waveguide network with 2.6λ0 port to port separation [1].