Application of planar multibeam array antennas to diversity reception

A method is proposed for constructing a diversity branch with each beam of a planar multibeam array antenna (MBAA), and its diversity reception characteristics are evaluated. The proposed method is a kind of directional diversity. If the beam-forming network of the MBAA is lossless, each beam is orthogonal to the other so that a branch configuration with its correlation coefficient close to zero can be expected. With respect to a three-element planar MBAA that has an easy hardware implementation, computer simulations assuming a Rayleigh distribution environment and an indoor diversity reception measurement with test antennas were carried out. The effectiveness of the method is confirmed as well as good agreement between the numerical results and the measurement results in the Rayleigh distribution environment. The diversity gain at the 1 percent value of the cumulative distribution by computer simulation is about 10, 13 and 14.5 dB for 2, 3 and 4 branches. Improvement of slightly less than 1 dB is expected for the addition of one extra branch.