Abstract: A 4-element high-gain circularly polarized microstrip antenna array operating at Ka-band is designed, analyzed and fabricated, and the work is reported in this article. The sequential rotation method and series-parallel feed technique are employed in the power distribution circuit for the array to improve antenna performance. The loss of the feed lines is also reduced, thus achieving high gain. The problem of unreasonable spatial arrangement is solved by using the L-shaped microstrip matching branch. The feeding network is integrated on the same substrate of the antenna elements, which makes the fabrication and integration of the system easy. The measured results show that the antenna array has achieved good performance. The proposed antenna has the advantages of small volume, light weight, compact configuration, and ease of integration. It demonstrates a good prospect of application in airborne phased array radar and satellite communication systems.

Key words: circular polarization, microstrip antennas, antenna array, gain measurement, millimeter wave