Broad-band radial slot antenna fed by coplanar waveguide for dual-frequency operation

A novel design of a broad-band radial slot antenna fed by a coplanar waveguide for dual-frequency operation is presented. Various frequency ratios, within the range of about 1.3 to 2.1, of the two operating frequencies can be obtained by varying the included angle between the radial slots and/or by varying the length of the central slot pair. The bandwidth of the lower operating band lies in the range of 2.4% to 9.7%, while that of the upper band is much wider and ranges from 17.4% to 23.2%. Radiation patterns at the two operating frequencies are broadside and bidirectional. Details of the antenna design and the experimental results are presented and discussed.