Miniaturized wide‐band microstrip grid array antenna loaded with slow‐wave transmission line

Abstract

A miniaturized microstrip grid array antenna (MGAA) in X‐band is proposed in the paper. The antenna consists of a radiation grid array, a feed network and a metal back cavity. The 2 × 2 planar grid array is constructed by using four MGAAs as subarrays. MGAA does not require complex feeders in contrast to microstrip patch arrays. Furthermore, a curved slow‐wave transmission line (SWTL) is adopted as the long side of grid. The SWTL not only reduces the physical size of the grid while keeping its electrical size unchanged, but also improves the impedance matching and greatly broaden the bandwidth of the antenna. A fabricated prototype was measured in the microwave chamber. The results indicate that the impedance matching band of |S11| < −10 dB is from 9 to 10.5 GHz (15.4%), and the maximum gain is 19.2 dBi. Meanwhile, the projected area of the antenna is reduced by about 40% by loading the SWTL.