Design of a narrow-size planar monopole multiband antenna with double L-shaped slots

A narrow-size planar monopole antenna for triple-band operation is presented. The proposed antenna consists of a half E-shaped metal patch, a 50 ohm coplanar waveguide (CPW) transmission line and a branch extended from the ground. The narrowness of the antenna is achieved by applying the asymmetric coplanar strip (ACS) structure to the prototype one. The multiband characteristic of the antenna is due to the various meandered current paths excited in the different parts of radiation structure. There are double L-shaped slots within the antenna, one in the ground and the other in the E-shaped patch. By etching the slots, band-rejected filtering properties outside the PCS/WiMax/ WLAN bands are achieved. This technique is suitable for reducing the size meanwhile maintaining the main characteristic of antennas.