A small asymmetric coplanar strip fed tri-band antenna for PCS/WiMAX/WLAN applications

In this paper, a small asymmetric coplanar strip (ACS)-fed monopole antenna for tri-band operation is proposed. The proposed antenna is composed of an arc-shaped monopole strip, a rectangular-shaped branch, and an L-shaped strip attached to an extension of the feed line. The three operating bands are obtained from the excitation of resonances due to these strips. The resonances can be controlled by tuning each individual strip separately. The measured results show that the proposed antenna has −10 dB impedance bandwidth of 250 MHz from 1.75 to 2.0 GHz, 300 MHz from 3.2 to 3.5 GHz and 1.8 GHz from 5.0 to 6.8 GHz. Further, the antenna has good bidirectional radiation patterns in the E-plane, omnidirectional radiation patterns in the H-plane and reasonable peak gains in the all operating bands. With these features and a compact size, the proposed antenna will be suitable for PCS 1900, 3.5/5.5 GHz WiMAX and 5.2/5.8 GHz WLAN portable wireless communication applications.