Pattern control of UWB printed antenna on large ground plane

The performance of device-integrated ultra-wideband (UWB) antennas are significantly affected by the ground plane on which they are mounted. This is mainly due to the high field coupling between the antenna and the device ground plane. The coupling causes the ground plane to radiate and degrades the radiation characteristics of the antenna. In this paper a small printed coplanar waveguide (CPW) fed UWB antenna is integrated into a relatively large printed circuit board (PCB) that functions as the device ground plane. The original CPW feeding of the antenna is transformed to a 50Ω microstrip line suitable for connecting off-the-shelf RF components. A technique is proposed to mitigate the unwanted effects of field coupling between antenna and the PCB. Two pairs of short-circuit quarter wavelength transmission lines (RF chokes) are incorporated in the design in order to reduce the flow of surface currents on the edges of the PCB. This method enhances the antenna radiation patterns after integration. A prototype of the fully integrated antenna has been manufactured and verified via measurements.