Stacked Arrangement of Rectangular Microstrip Patches for Circularly Polarized Broadband Performance

Design and analysis of a single-feed arrangement of stacked rectangular patches is proposed, which is capable of providing circular polarization along with broadband performance. An antenna is designed on a glass epoxy FR-4 substrate with overall thickness of the structure less than 8 mm or 0.11λ₀. The patch area of the corner truncated driven patch is marginally smaller than that of a parasitic patch to achieve improved performance. Both driven and stacked patches have narrow slots of unequal size in a way that their centers lie one over the other. The locations of the feed point, the amount of corner truncation of the driven patch, and the size of slots on both the driven and the stacked patches are optimized. Axial ratio bandwidth better than 11% and impedance bandwidth better than 27% may be achieved with the proposed geometry. Measured gain and axial ratio variations of the proposed antenna with frequency are compared to simulated results for better understanding. The measured E- and H-plane radiation patterns in the entire impedance bandwidth are identical in shape, and the direction of maximum radiations is normal to the patch geometry. In the entire axial ratio bandwidth range of the proposed antenna, the E-plane left circularly polarized patterns are nearly 15 dB higher than the corresponding right circularly polarized patterns .