Improved Sidelobe-Suppression Microstrip Patch Antenna Array by Uniform Feeding Networks

Abstract

This article presents a design of a single-polarization, $4\times 4$ microstrip patch antenna array, operating at the $K_{a}$ -band. An integrated microstrip network with the aid of using feeding probes excites the antenna array. Simulation and measurement results show that the array operates in a wideband frequency range (return loss RL ≥ 15 dB) from 32 to 36.4 GHz with a low sidelobe level (SLL ≤ −15 dB). To obtain a wide bandwidth, each antenna is fed with a capacitive patch and enclosed by an integrated metallic cavity. Here, we show that an antenna array with an SLL could be achieved by mirroring and feeding the radiating elements with equal excitation. The design is also applicable to a dual-polarized antenna, as it does not only lower the sidelobe level but also improve the cross-polarization without increasing the circuit complexity. An antenna prototype has been realized with an experimental bandwidth better than 3 GHz and a sidelobe level of −15.6 dB. These excellent measured results prove that this method with a simple design approach is feasible for an antenna array with high suppression of sidelobe and cross-polarization.