Radiation performance improvement of wideband microstrip antenna array using wideband AMC structure

摘要

In this paper, the radiation performance of an antenna array is improved by designing a new wideband artificial magnetic conductor (AMC). The proposed AMC surface operates at the frequency of 3 GHz with +/- 90 degrees reflection phase bandwidth of 22%. In order to identify the key design parameters of the AMC structure, a parametric study is performed. To improve the radiation performance of the antenna array, an AMC reflector is developed through utilizing an array of 2 x 8 periodic patches of AMC unit cells. By this technique, the front to back ratio of the designed antenna array is enhanced about 16.27 dB. It is concluded that tuning of the AMC dimensions for controlling the reflection coefficient at each port of antenna array during beam steering is necessary. Because of the using of the AMC surfaces as a reflector instead of conventional PEC surfaces, size reduction of the antenna array in the order of 20% is achieved. In this study, a circuit model for single element of the antenna array with considering AMC loading effect is introduced, which predicts the bandwidth behaviour of the proposed antenna. The final designed antenna array exhibits low level of cross polarization making it well-suited for tracking radars and electronic warfare applications. The proposed antenna with the AMC reflector is fabricated and measured. The measured -10 dB impedance bandwidth and peak gain of the proposed antenna is 20% (2.7-3.25 GHz) and 13.4 dBi, respectively, which are compatible with the simulation results.