A planar circularly polarized antenna with high radiation gains

Abstract

Low-profile, high-gain circularly polarized antennas are highly desired in modern space and communication systems because they not only reduce the size, weight, and cost of the communication system but also reduce polarization mismatch resulting from the multipath interference of wave propagation. Because of their low cost, simple structure, and good integration capability, microstrip patch antennas have attracted much interest for circular polarization (CP) applications. This type of antenna has a good CP character and maintains a compact profile. However, they can only provide moderate radiation gain and suffer from high conductor losses and low radiation efficiency. In particular, these drawbacks become serious for large array applications, which require complicated feeding networks and high radiation efficiency. Generally, few planar CP element antennas that are suitable for array applications and can provide a radiation gain higher than 8.0 dBi. In this paper, we introduced a planar high-gain circularly polarized element antenna which can be adopted for planar array applications. Two pairs of slots are etched on the surface of a SIW cavity. By introducing an additional metallic via-brick into the SIW cavity, two orthogonal degenerate radiation modes, TE 120 -like and TE 210 -like modes, are excited for those two pairs of slots. Then a CP radiation is obtained with a high simulation radiation gain higher than 10.28 dBi. To demonstrate the array application, a 4×4 array antenna is designed with a compact beam-forming network. Experiments are carried out to verify designed prototypes. Measured results show that the element antenna has a high gain up to 9.6 dBi, and the 4 × 4 array antenna has a high gain up to 20.1 dBi with a high radiation efficiency of 83%.