| Budget Amount *help |
¥4,800,000 (Direct Cost: ¥4,800,000)
Fiscal Year 1994: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 1993: ¥4,100,000 (Direct Cost: ¥4,100,000)
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| Research Abstract |
Wireless communication systems such as mobile telephones and personal handy phones are going to be introduced in date communication networks. For this realization, techniques avoiding fading due to multipath propagation have to be established. This research proposes the application of multibeam array antennas as antennas of diversity reception, and evaluates their performance by conducting trial manufacture and propagation experiment. 4-and 8 elements arrays of rectangular or circular microstrip patch antennas are fabricated at the frequency band of 1.5 GHz, and the radiation pattems are evaluated. Butler matrix networks are utilized as the BFN.The array of 8 elements are arranged on a plane two-dimensionally, with the array being a regular hexagon plus 1 element shape. This is the first successfully manufactured planar multibeam array in the world. The measured radiation pattems coincide with the theory, and the orthogonality between every beams are good. The propagation experiment have been conducted inside a room with 6.9 * 8.7[m] area, where 4 kinds of environment are prepared, i.e. (a) the space looking the transmitting antenna is free or (b) obstructed, and (c) the shutter at the windows which is good reflectors of electromagnetic waves are pulled down or (d) up. The observed diversity gain at 10% cumulative distribution was 7.03 dB by 8 branches. The numerical simulation estimates one at 1% cumulative distribution to be 15.78 dB by 4 branches, and 19.81 dB by 8 branches. Later, a new measuring equipment with higher accuracy was introduced, and a planar array of 3 elements circular patch antennas with aperture coupling and circular polarization was tested at 2.5 GHz band, where a modified Blass network was utilized as the BFN.The diversity gain in this case for 1% cumulative distribution was estimated to be about 13 dB,which was in good agreement with the numerical simulation.
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