0883-6272/86 $3.00 + .00 Copyright ® 1986 SUNS AT Energy Council RECTENNA COMPOSED OF A CIRCULAR MICROSTRIP ANTENNA KIYOHIKO ITOH, TAKEO OHGANE AND YASUTAKA OGAWA Department of Electronic Engineering Hokkaido University Sapporo, 060 Japan Abstract — One of the big problems in the SPS system is reradiation of the harmonic waves generated by the rectifying diode. We have proposed the use of a circular microstrip antenna (CMSA), since the CMSA has no higher resonance-harmonic of integer multiple of the dominant resonance frequency. However, characteristics of a large rectenna array of CMSA’s have not been clarified. This paper is concerned with the absorption efficiency of the rectenna composed of the CMSA. The efficiency is estimated explicitly using an infinite array model. The results show that the absorption efficiency of the infinite rectenna array composed of the CMSA is 100%. Also, this paper considers the effect of the losses of the CMSA. INTRODUCTION "Rectenna,” the Earth Station Terminal in the Solar Power Satellite (SPS) system converts the microwave power (2.45 GHz) transmitted from SPS into the DC. The structure of the rectenna is divided roughly in two parts — receiving antenna and rectifying circuit. One of the big problems in the SPS system is reradiation of the harmonic waves generated by the rectifying diode. Therefore, the low-pass filter must be inserted between them in order to prevent the harmonic polluting radio communication environments. The SPS baseline rectenna has been developed by Raytheon Company, and they have adopted a dipole antenna with ground plane as the receiving antenna (1). Also, Gutmann et al. have investigated the possibility of using the Yagi-Uda antenna. However, all of the above-mentioned antennas belong to the linear antenna and have the characteristic that higher resonance-harmonic of integer multiples of its dominant resonance frequency exist. These features are undesirable for suppression of higher harmonic reradiation. We have proposed the use of a circular microstrip antenna (CMSA) as a competitor to the linear antenna for the rectenna in the SPS system (2), since the CMSA has no higher resonance-harmonic of integer multiple of the dominant resonance frequency. Moreover, the microstrip antenna can be printed on the same substrate with other devices. It can realize the very thin rectenna. And this configuration makes manufacture and maintenance very easy.
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