Small Circularly Polarized U-Slot Wideband Patch Antenna

A single-feed circularly polarized (CP) patch antenna at L-band is designed and built using the recently developed U-slot loaded patch technique. With the presence of the U-slot, the antenna fabricated on a high-dielectric-constant (ε
_r
= 10.02) substrate achieves a reasonable axial-ratio bandwidth. At the operating frequency of 1.575 GHz, the size of the patch is 0.13λ
_o
× 0.13λ
_o
, while the ground size is 0.315λ
_o
× 0.315λ
_o
and the thickness of the substrate is 0.05λ
_o
. The measured gain is 4.5 dBi, and axial-ratio bandwidth is 3.2%.