Compact Microstrip Patch Array Antenna With Parasitically Coupled Feed

A 3 × 3 parasitically coupled microstrip patch array antenna is proposed in this communication. The array consists of nine microstrip patches. The center patch fed by a probe works as a driven element while the other eight surrounding patches are parasitic elements. Four microstrip lines located between elements are employed as feed network to distribute coupled energy in both the E- and H-planes of the array. Thus, the 3 × 3 elements can be arranged on a single-layered substrate and excited simultaneously. The antenna has a simplified feed structure and a compact size. Meanwhile, the experimental results show that the proposed antenna has a broad bandwidth of 15.4% from 18 to 21 GHz and a maximum gain of 14.8 dBi.