A Board Omnidirectional Coplanar Waveguide Antenna with Choke Sleeve

A board omnidirectional coplanar waveguide (CPW) antenna is designed with a choke sleeve in this paper to realize high gain and good radiation performances. The antenna employs four λg/2 long units which are staggerconnected to achieve in-phase current on each unit. In this way, a high gain omnidirectional antenna can be obtained. By loading the designed choke sleeve which is aimed at reducing surface current on the coaxial feeder outer conductor and an additional infinite ground, this board antenna performance would not be affected by an even longer coaxial line. The simulation results show that the operating frequency with reflection coefficient less than -10 dB ranges from 5.71 GHz to 6.05 GHz. The maximum gain at the center frequency of 5.8GHz in the boresight is 5.3 dBi. The out-of-roundness of the omnidirectional radiation pattern in the azimuthal plane (XOY plane) is less than 1.3 dBi. Also, the reflection coefficient, gain and radiation patterns are showed with and without choke sleeve for comparison. Radiation patterns could be improved by the added choke sleeve. The proposed antenna with simple configuration, low profile, compactness and low fabrication cost becomes a candidate as a board antenna for WiMAX applications.