Small Printed Tri-band Antenna with Reduced Ground-plane Effect

摘要

This paper presents a small printed tri-band antenna with a reduced ground-plane effect for WLAN/M-WIMAX applications. The radiator and ground plane of the antenna are etched on a printed circuit board with an overall size of 25 x 24.5 x 0.762 mm(3). A rectangular notch and a circular slot are cut from the radiator while an asymmetrical strip is attached to the radiator. The simulation and measurement suggest that the printed antenna achieves three operating bandwidths of 2.4-2.484 GHz and 5.15-5.35 GHz for WLAN, 3.3-3.69 GHz for M-WIMAX for a 10-dB return loss, and high gains on Y-Z plane of 2.1, 3.3 and 4.8 dB at 2.4, 3.5 and 5.2 GHz, respectively. In particular, the ground-plane effect on impedance performance is significantly reduced by minimising the size of the ground plane and then by cutting a notch and a circular slot from the radiator because the electric currents on the ground plane are significantly suppressed at all the operating bandwidths. In addition, a study on the geometrical and electrical parameters of the proposed antenna may be a useful reference for antenna engineers.