5.8-GHz Patch Antenna with an Enhanced Defected Ground Structure for Size Reduction and Increased Bandwidth

Abstract

A coaxial feed patch antenna with a thumb-shaped defected ground structure (DGS) is proposed to simultaneously reduce the antenna size and improve bandwidth. The size of an antenna can be reduced by incorporating a DGS to change the electromagnetic field distribution between the patch and the ground. The proposed thumb-shaped DGS effectively widens the antenna bandwidth by generating two resonant frequencies on either side of the operating frequency, as determined by the patch length. In addition, the effect of the DGS on the ground body of a radio frequency connector is minimized by maintaining a sufficient distance between the DGS and the feed point when the connector is attached. The electromagnetic wave simulation results, which depend on the physical dimensions of the DGS, provide the characteristics of the proposed antenna. The measurement results for the proposed 5.8-GHz antenna, implemented on a 1 mm FR4 printed circuit board, give an antenna gain of 4.4 dBi and a −10 dB bandwidth of 580 MHz. Compared with a conventional 5.8- GHz patch antenna implemented on the same substrate, the proposed antenna provides a 3.22-fold bandwidth improvement and 10.2% patch size reduction.