Design of a Quad-Band Monopole Antenna with Independent Frequency Control

A coplanar waveguide (CPW)-fed I-shaped monopole antenna with independent frequency control characteristic is presented for simultaneously satisfying the global positioning system (GPS), wireless local area network (WLAN), and worldwide interoperability for microwave access (WiMAX) applications. It is printed on an FR4 substrate with a single-layered metallic structure and the overall dimensions are 45 x 25 x 1.6 mm(3). The proposed antenna consists of an I-shaped monopole, a pair of split-ring resonators (SRRs), and a coplanar ground plane. The unique advantage of this study is that the four frequency bands are generated individually by different radiating elements. That is, each of them can be controlled independently with little interference from others, which brings added convenience to the antenna design, optimization and debugging processes. Simulated and measured results both demonstrate that it can cover the 1.575 GHz GPS (1.57-1.59 GHz); 2.4/5.2/5.8 GHz WLAN (2.4-2.485, 5.15-5.35 and 5.725-5.825 GHz) and 3.5/5.5 GHz WiMAX (3.40-3.60 and 5.25-5.85 GHz) applications with satisfactory radiation patterns and acceptable gains.