Small planar monopole ultra-wideband antenna with reduced ground plane effect

A printed monopole ultra-wideband antenna with reduced ground plane effect is presented. The ground plane dependence of the antenna is reduced by cutting a slot in the radiator, and then introducing a strip in the slot, to reduce the current distribution on the ground plane at a desired frequency. At this frequency, the impedance performance of the antenna is mainly affected by the monopole radiator, thus reducing the effect of the ground plane on the antenna. Measurement results confirm that this approach works well and also show good far-field properties of the antenna. The antenna is printed on a small FR4 substrate with an area of 25 mm²; it achieves an impedance bandwidth of 3.6 to over 11 GHz, and broadband ground plane effect suppression around the design frequency of 5 GHz.