comes zero, since all of the incident power flow is along x-z plane or in the direction of propagation of the grating lobe. This phenomenon cannot be observed for an infinite array of dipoles with ground plane where the cancellation occurs between dipoles and their images (3). However, the above discussion ignores the effect of the thickness of the substrate. In fact, it is predicted that the efficiency is greater than zero because the surface wave generates before the grating lobe. This discussion can be extended to the case of the CMSA with losses. When we consider the ohmic and the dielectric losses of the CMSA, the active conductance is rewritten as follows: Both the ohmic and the dielectric losses of the CMSA are affected by the thickness of the dielectric substrate. Figure 4 shows the absorption efficiency under the existence of losses, where the relative dielectric constant of the substrate is 2.6 and tan8 = 2.2x 10-3. As may be seen from this figure, the greater spacing provides the smaller efficiency. In other words, the efficiency becomes less than 100% even if there is no grating lobe. Therefore, it is necessary to define the limit of the absorption efficiency when we design the rectenna practically. CONCLUSION We have estimated the active admittance and the absorption efficiency of the infinite array of the CMSA’s. The infinite array model made these equations very simple, and this paper shows that the absorption efficiency of the infinite rectenna array composed of the CMSA is 100% . The results indicate the possibility of realization of the very thin rectenna which uses the CMSA as the receiving antenna. Acknowledgment — This research project is supported by a grant from the Ministry of Education, Science and Culture under project 56460102. REFERENCES 1. R.J. Gutmann et al.. Directional Receiving Elements and Parallel-Series Combining Analysis, NASA-CR-151866 (N79-16039), 1978. 2. K. Itoh. Y. Akiba, T. Ohgane, and Y. Ogawa, Fundamental Study on SPS Rectenna Printed on a Sheet of Copper Clad Laminate, Space Solar Power Review 5, 149-162, 1985. 3. L. Stark, Microwave Theory of Phased-Array Antennas — A Review, Proc. IEEE 62, 1661-1701, 1974. 4. S. Adachi, O. Suzuki, and S. Abe, Receiving Efficiency of an infinite Phased Array Antenna above a Reflecting Plane, IECE Japan, J64-b, 6, 566-567, 1981.
RkJQdWJsaXNoZXIy MTU5NjU0Mg==