Reconfigurable Circular Polarized Microstrip Patch Array Antenna with Half-Wavelength Delay Line Switching

This study demonstrates and constructs a 1 × 2 patch array antenna structure for reconfigurable circular polarization (CP) utilizing a simple switching mechanism. The antenna's array elements are mounted on a 0.8 mm thick Teflon substrate. Two slot lines of width 0.2 mm form four slot-microstrip junctions with the microstrip lines, which are above the substrate. The microstrip patches are fed orthogonally from the slot-microstrip junction via a quarter-wavelength transformer. The SPDT switch coordinates the phase difference between the two orthogonal excitations. The outcome of the design is achieved by a parametric simulation. The relative power level difference greater than 30 dB and axial ratio value less than 3 dB for both left-hand circular polarization (LHCP) and right-hand circular polarization (RHCP) show that the antenna displays very good CP performances and a reflection coefficient less than -10 dB indicating good impedance matching of the antenna. The antenna has an impedance bandwidth of 700 MHz and an axial ratio bandwidth of 250 MHz. The antenna is particularly efficient across the X-band spectrum, as the directivity (11.95 dBic) and gain (11.25 dBic) values vary minimally across the operational frequency range.