Coupling Network Design for Bandwidth Enhancement of Microstrip Antenna Array

A coupling network is proposed to widen the operating band of the dual-layer coupled microstrip antenna array, which is a novel method for the performance improvement of unevenly-fed antenna. Through adding the network, the bandwidth of the antenna array extends to 40.2%, 13.8% and 10.1% wider than those of the single antenna and the array without the network, respectively. Meanwhile, the coupling network has little impact on the radiation pattern and gain. Results indicate that the coupling network is promising to be applied in wideband phased array.