Design of Compact Circular Polarization Electrically Small Antennas

The design of a compact circular polarization (CP) electrically small antenna (ESA) is carried out and presented in this paper. The designed antenna consists of a planar circuit board (PCB) on which two 3-dB hybrid couplers are fabricated for providing left-hand circular polarization (LHCP) and right-hand circular polarization (RHCP) waves, and two ceramic substrates covered by thin metal films with the high dielectric constants of 20.5 and 39 and the sizes of 25x25x6 mm and 18×18×4 mm, respectively. This compact CP ESA can realize a coverage of ±75° elevation angle with gain above -4dB in the frequency band of 1518 - 1525 MHz for RHCP and in the band of 1668 - 1675 MHz for LHCP, and a coverage of ±60°elevation angle with gain above - 2dB in the band of 1575.42±1.023 MHz for RHCP.