Millimeter-wave circularly polarized complementary antenna array based on sequential rotation technique

In this paper, a sequentially rotated (SR), broadband, circularly polarized (CP), high gain, low profile magneto-electric (ME) dipole antenna array is proposed. According to the design evolution, the antenna is derived from a linearly polarized antenna fed by an inverted "L" microstrip. First, the antenna elements are cut to introduce a pair of "L" bends, and the antenna complementary theory is applied to cut the corners of the other pair of patches as well, thus increasing the axial specific bandwidth of the antenna. The axial bandwidth of the antenna is then further increased by fine-tuning the L-bends to create high frequency axial resonance points. For verification, a 4 x 4 sequential rotating array is designed using a microstrip line feed. Measurement results show that the array has an ARBW of 66.4% in the range 18.29-36.83 GHz, an IBW of 66.8% in the range 15.28-37.83 GHz and a peak gain of 17.1 dBic.