Abstract: A planar microstrip array antenna with a beam tilt, which comprises a plurality of pairs of circularly polarized wave radiating elements, the orientation angles of the two radiating elements in each pair being different by a predetermined angle within the plane of the planar antenna. The antenna further comprises a feed line for supplying electric power to the radiating elements. The feed line is provided with a plurality of pairs of terminal feeding portions which diverge corresponding individually to the pairs of circularly polarized wave radiating elements. The paired feeding portions are equal in electrical length. Since the respective orientation angles of the paired radiating elements are different, a phase difference is produced between the radiating elements, thus providing a beam tilt. Since no phase shift portion for producing a phase difference is formed between the paired terminal feeding portions, the configuration of the feed line is simple.