Electronically steerable passive array radiator antennas for low-cost analog adaptive beamforming

Electronically steerable passive array radiator antennas are proposed for low-cost analog adaptive beamforming. Unlike conventional digital beamforming, they require only one transmitter or receiver. For 2-, 3-, 4- and 5-element antennas, beam and null steering characteristics are estimated by the method of moments. It is numerically shown that full 360-degree continuous azimuthal beam/null steering is possible by at least 4 elements. Also shown is that a directive gain of 9 dBi +/-1 dB and null depth of -50 dBi +/-10 dB are obtained by 5 elements, along with an associated return loss of better than 20 dB at the feeding port. Their drastically low cost and low power consumption could help to achieve adaptive antennas for portable wireless user terminals.