Circularly Polarized Antennas with Stable Phase Center

Abstract

Nowadays, global navigation satellite system (GNSS) is intensively used in various fields. In the measurement of GNSS, observation values are based on the position of the phase center of the receiver antenna. But the phase center and the geometric center of the antenna are essentially inconsistent, with deviation varying from a few millimeters to centimeters, which has a great impact on the high positioning accuracy. Therefore reducing the deviation of the phase center is a crucial issue in the design of a high-precision antenna. Lots of planar circularly polarized microstrip antennas have been developed recently with the advantages of light weight, low profile and easy processing. In designing a single-feed microstrip patch antenna with circularly polarization (CP), perturbation methods were frequently used, including truncating a pair of patch comers in the radiating square patch, embedding a cross slot on the radiating patch, and loading four unequal circular-patches on the four corners of square patch]. But these methods made the structure asymmetric and caused the phase center to shift. A stacked double-patch microstrip antenna with four coaxial probe-feeds presented recently had impressively small deviation of the phase center. A center-fed CP antenna with two small square stubs was also proposed recently. In this talk, we will introduce a novel method to design CP antennas with stable phase center proposed by us most recently, in this method, a annular slotted center-fed CP microstrip antenna is loaded with two concentric annular slots and three embedded conducting tabs. The new antenna can generate high quality CP radiation without introducing any perturbation, demonstrates the merits of structural symmetry and compact patch size. The overall symmetry of the patch conductor ensures that the antenna has a very stable phase center.