Low Sidelobe Coupled Broadband Microstrip Array Antenna With Non-Uniform Spacing and Variable Groove Length

To reduce the sidelobe level (SLL) and widen the bandwidth, this article uses the differential evolution algorithm to optimize the array element spacing and excitation amplitude, and designs an 8-element coupled microstrip array antenna with non-uniform spacing and variable groove length. Based on the power equally divided feed network, the non-uniform length of the groove to achieve a quantitative change in the excitation amplitude. This method does not need to adjust the width of the microstrip line of the feed network one by one, nor is it limited to an array of equal spacing, which simplifies the complex design process. And to establish a mathematical relationship of all feeder segments to ensure that all array elements are in phase excitation under unequal spacing conditions. At the same time, the H-groove coupling feed form reduces the antenna Q value and increases the bandwidth. The measurement results show a gain of 16 dBi and an SLL of 19.5 dB within the operating bandwidth. And the antenna has a voltage standing wave ratio of less than 1.5 in the range of 13.84 to 15.62 GHz, which meets the bandwidth requirement of SatCom on-the-move.