-Shaped Differential Fed Patch Antenna for a GaN
Base Station Transmitter
In this paper, a differentially fed, structurally simple, patch antenna, operating at 5.2 GHz is presented. The proposed antenna is particularly designed for a base station, Gallium Nitride (GaN) transmitter. The antenna is composed of an H-shaped patch, backed by a ground plane, with two differential feeds placed at the longitudinal edges. The size of the antenna is 0.55λ0 x 0.49λ0 x 0.27λ0 (where λ0 is the free space wavelength at the center frequency). A prototype of the stand-alone antenna is designed, fabricated, and measured. The antenna offers a voltage standing wave ratio (VSWR) bandwidth of 4% and a differential impedance of 100, which matches most of the differential integrated circuits. The measured gain and directivity of the proposed differential antenna are 5.3 dBi and 7 dB, respectively. From simulation it is observed that the proposed antenna possesses a front to back ratio of 15.69 dB and a 3 dB beamwidth of 84˚. The measured peak efficiencies of the antenna in the lower and higher bands are 84% and 59%, respectively. Details of the design and lumped model, along with the experimental and simulated results, are presented and discussed. The effect of scaling different design parameters for operation at different frequency bands is considered as well.