A Novel Harmonic Suppressed Coplanar Waveguide (CPW)-Fed Slot Antenna

A novel open-ended ungrounded coplanar waveguide (CPW)-fed slot antenna for broadband harmonic suppression is presented. By employing two folded L-shaped slots into the surrounding ground planes, a fundamental resonance at 2.4-GHz WLAN along with its third harmonic is obtained. To suppress the harmonic, a technique with low design complexity, including two rectangular slots etched on the center conductor of the CPW transmission line, is proposed and studied. Simulated and measured reflection coefficients indicate that the proposed structure effectively suppresses the third harmonic up to 22 dB between 3 and 10.5 GHz with a maximum ripple of 3 dB. In addition, the radiation patterns and peak gain of the antenna can be suppressed at least 19 and 16.8 dB, respectively at the third harmonic frequency of 7.2 GHz.