Novel compact design of CPW-fed circular patch antenna

Abstract

Due to low radiation leakages and easily integrated with active devices in the same side of the planar substrate, several related designs of CPW-fed microstrip antenna with different coupling slots have been studied. However, very few designs for a compact microstrip antenna with a CPW-fed line have been published in the open literature. The only compact design with CPW-fed line that has been proposed uses meandered slots in the antenna's ground plane. We demonstrate that by increasing the vertical arm's length of the U-shaped coupling slot connected with coplanar waveguide (CPW) feed line, the fundamental resonant frequency of the circular microstrip antenna can significantly be lowered. Moreover, by perpendicularly bending a vertical portion of the U-shaped coupling slot back to back, which can be considered as a pair of introduced rectangular slots connected with the vertical portion of the U-shaped slot, a modified U-shaped slot is presented in this study. It is found that the proposed design causes more significantly lowering of the antenna's fundamental resonant frequency. Prototypes of the proposed design have been successfully implemented, and experimental results are described in detail.