High-Gain and Wideband Circularly Polarized Endfire Leaky-Wave Antenna Array Based on the Complementary Dipole

A circularly polarized (CP) endfire leaky-wave antenna (LWA) array with the merits of a high-gain and broad operation band is proposed in this communication. This array configuration is composed of double-row antenna cells arranged linearly, which derives from the performance of the complementary dipole (loop and electric dipole). By introducing the coupling loop and the electric dipole along both sides of a metallic parallel strip line (PSL), effective radiation is generated from this structure due to the periodic perturbation. Based on the intrinsic 90° phase differences of the complementary dipole, CP performance is easily achieved by turning the antenna unit size reasonably. Similar to the Yagi antenna, this linear antenna array achieves endfire radiation. A fabricated prototype has verified the design concept, which shows that the proposed antenna has a relative impedance bandwidth of 51.1%, a 3 dB axial ratio (AR) bandwidth of 25%, and a gain of 1.1–13.59 dBi within the operation band.