Single-Feed Circularly Polarized Microstrip Antenna With Bethe Holes on the Radiating Patch

A novel single-feed (SF) circularly polarized (CP) microstrip antenna with Bethe holes on the radiating patch is introduced. The proposed antenna provides a small axial ratio (AR) over a relatively large frequency range and the CP quality is good over a wide range of radiation angle. The structure is of a single layer, providing easy fabrication at low cost.