COMPACT DUAL-BAND DUAL-RING PRINTED MONOPOLE ANTENNAS FOR WLAN APPLICATIONS

Three dual band planar monopole antennas for wireless local area network (WLAN) application are proposed. The antennas have common conflguration in the form of rectangular, rhombic and annular double rings. All the antennas use the self similarity property to exhibit dual band characteristics. The proposed antennas cover the frequency bands of the IEEE 802.11a/b/g (2.4{2.48GHz, 5.15{ 5.35GHz and 5.725{5.825GHz), and have radiation patterns that are; almost omnidirectional in the H-plane, and like monopole pattern in the E-plane. The simulation results are analyzed and compared with measured results for veriflcation. During the last decade, enormous advancements in designing wireless systems have been achieved. The portable devices in the market are ofiering many advantages like the small size, low cost and the support of many applications like Bluetooth, internet service, making calls and GPS services. Variety of applications, which are working on designated frequency bands, need antennas operating on these bands to be mounted in the same device. The use of more than one antenna in the same device is not a practical solution, because of the limited size in the new wireless devices. Therefore, various antennas working on dual or multi bands have been developed by the researchers over the years. Taking the beneflts of utilizing the self similarity property of fractal shapes a dual band fractal monopole was proposed by (1,2). The use of slot structures to achieve multi-band characteristics was proposed in (3{5). The use of ring shaped antenna to operate on dual