Investigation of isolation enhancement and tune‐ability in patch antenna arrays

Abstract

AbstractThis paper reports the study of a tunable isolator based on a four‐strip resonant structure to reduce the mutual coupling between two patch antennas. Unlike other decoupling structures with a fixed center decoupling frequency, this design provides tunable mutual coupling reduction frequency response and adjustable mutual coupling level by integrating a varactor diode into the strip isolator. This study investigates the effect of the position and capacitance of the varactor diode on mutual coupling. In addition to tune‐ability, the tunable four‐strip resonator reduces the coupling level at all frequencies around 3.5 GHz by at least 6 dB to less than –28 dB without degrading the impedance bandwidth. Compared to the case with the four‐strip resonator structure but without the varactor diode, the isolation is further improved by 2 dB or more. The measured results are consistent with the simulation results.