Compact Tri-Band Monopole Antenna with a Parasitic E-Shaped Strip for WLAN/Wimax Applications

A compact coplanar waveguide (CPW)-fed printed monopole antenna comprising of two symmetrical C-shaped radiating elements, a parasitic E-shaped strip, and a truncated CPW ground for WLAN/WiMAX applications is proposed. By embedding a parasitic E-shaped strip inside the two symmetrical C-shaped radiating elements, four resonant frequencies and three operating bands are obtained. By etching two quarter-circles in the CPW ground, impedance matching condition of the third operating band is significantly improved. A prototype of the proposed antenna has been constructed and experimentally studied. The measured results show that three distinct operating bandwidths with 10 dB return loss are about 500 MHz (2.33-2.83 GHz), 700 MHz (3.27-3.97 GHz) and 2.37 GHz (4.3-6.67 GHz), covering all the 2.4/5.2/5.8 GHz WLAN and 2.5/3.5/5.5 GHz WiMAX bands. Furthermore, the antenna has a simple planar structure and a small volume of only 31 × 21 × 1.6 mm. Good radiation characteristics and acceptance peak realized gains are obtained over the operating bands.