Construction of BFN for multibeam array antennas used for diversity reception

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In view of the orthogonal properties of multiple beams created by array antennas with lossless BFN,this research aimed the economical realization of personal terminals capable of diversity reception with ideal properties that there is no correlation between beams. The main results are as follows.1.General theory has been developed for replacing the 2-D DFT to 1-DDFT.This has been done by introducing new concept of "simultaneous sampling" and "discrete equivalence", and made it possible to give a mathematical basis to Shelton's method of applying BFN for a linear array to a planar multibeam array.2.A hardware realization of FFT algorithm with basis 2^n3^mis equivalent to designing a BFN with 2^n3^m input and output ports. As an elemental network, a3*3 modified Blass network was designed and manufactured.3.The fundamental properties of a planar array with minimum ports, 3 antenna and 3 beam ports, has been clarified.4.A six elements planar microstrip patch antenna array was manufactured, and the diversity reception effect was investigated by indoor experiment. It was found that fading of 29.93dB was improved to 10.16dB,and that the diversity gain at the 1% value was 17.37dB for 6 branches and 14.9dB for 3 branches.