CPW-Fed Broadband Circularly Polarized Planar Monopole Antenna With Improved Ground-Plane Structure

A novel CPW-fed planar printed monopole antenna with broadband circular polarization (CP) characteristic is presented. The proposed antenna consists of a rectangle patch and an improved ground-plane. By appropriately adding a vertical stub and cutting a horizontal slit on the ground-plane, the impedance bandwidth of the antenna is enlarged, and its wide axial-ratio (AR) bandwidth is achieved. The measured results show that the proposed antenna has not only a broad 3-dB AR bandwidth of 44.9% (2.65 GHz, 4.58-7.23 GHz) with respect to the CP center frequency 5.90 GHz, but also a wide 10-dB return loss bandwidth of 76.9% (4.35 GHz, 3.48-7.83 GHz) centered at 5.66 GHz.