Compact broadband Circularly Polarized Truncated Parasitic Patch Antenna

Abstract

In this paper design of a microstrip patch antenna,
incorporating parasitic patches and Defective Ground Structure
(DGS) to achieve wide bandwidth, high gain and circular
polarization is presented. The initial single-patch design operating
at 5.55 GHz showed poor impedance matching (-4.52 dB), limited
bandwidth, and no circular polarization. To overcome these
issues, parasitic patches were added, resulting in dual-band
operation at 5.25 GHz and 7.45 GHz, with enhanced return losses
of -14.64 dB and -12.04 dB, with impedance bandwidths of 190
MHz and 160 MHz, respectively. The 100 MHz axial-ratio
bandwidth was the first step towards achieving circular
polarization. Further optimization resulted in a wideband
resonance at 6.1 GHz, with a bandwidth of 1.12 GHz (5.12–6.24
GHz) and an improved axial-ratio bandwidth of 1.10 GHz (5.09–
6.20 GHz). The gain increased to 10.7 dBi. In the final phase
incorporation of H-shaped DGS resulted in a broadband of 2.12
GHz (4.07–6.19 GHz) and axial-ratio bandwidths of 360 MHz and
870 MHz. The recommended antenna is appropriate for satellite
communications and radar applications.