Performance measurements of a two-branch diversity receiver with superdirective antenna array and decoupling and matching network

The paper presents a two-branch diversity receiver connected to two monopole antennas over a common ground plane. The influence of radiator coupling on the diversity performance of the receiver is investigated by measurement for different element separations down to lambda/20. Decoupling and matching networks (DMN) are known to mitigate the adverse effects of radiator coupling; however, practical network realisations have been shown to possess a low power efficiency. We demonstrate that despite this drawback, a practical DMN is able to deliver almost full diversity out of a highly superdirective two-element lambda/20 array. This also built a two-channel diversity QPSK (quadrature phase shift keying) mobile communications system and gathered statistics about the signal-to-noise ratio (SNR) for more than 90 minutes of received baseband data and for ten different two-port antenna arrays.