An Electronically Tunable Biomimetic Antenna Array

A two-element tunable biomimetic antenna array (BMAA) that uses a single varactor to achieve tunability over a relatively wideband is presented. The proposed device consists of two closely spaced quarter-wavelength monopole antennas operating at 600 MHz. The antennas are spaced at a distance of 2.5 cm and are coupled together using a tunable external coupling network (ECN). The ECN is designed to allow for tuning the response of the BMAA over the frequency range of 580-700 MHz. Over this frequency range, the proposed BMAA can enhance the phase difference between the output signals compared with a conventional array while extracting the maximum available power from the incoming wave. A prototype of the proposed tunable BMAA is designed, fabricated, and experimentally characterized. Measurement results are shown to be in good agreement with the theoretical analysis. The proposed tunable BMAA can be used to alleviate the bandwidth limitations of the previously reported two-element BMAAs.