Multi-band low-profile antennas for WLAN and WiMAX applications

Abstract

The demand for modern wireless communication systems have grown at a remarkable rate and the Wireless Local Area Network (WLAN) and Worldwide Interoperability for Microwave Access (WiMAX) frequency bands have been recognized as a cost-effective and reliable solution for high-speed wireless communication. The WLAN frequency bands are from 2.4 – 2.483 GHz, 5.15 – 5.25 GHz and 5.725 – 5.825 GHz, while the WiMAX frequency band is from 3.4 – 3.6 GHz, which are for the IEEE802.11a, IEEE802.11b, IEEE802.16d and IEEE802.16e standards. The objective of this dissertation was to develop a new and improved high gain WLAN antenna with a low profile and directional radiation pattern. The proposed antennas were based on an ultra-wideband slot radiating element, which consisted of a microstrip feedline with a strip-slot pair. The work also required the design of an artificial magnetic conductor (AMC) surface, to achieve a low profile antenna with high gain. The antenna combined with the AMC reflector, achieved a high gain and a directional radiation pattern. The design of the proposed antenna resulted in a triple-band WLAN antenna with an overall size of 80×80×10.01 mm3 with an average gain of 10.2 dBi across the WLAN bands. The antenna also achieved a directional radiation pattern with a front-to-back better than 24 dB in the WLAN bands. The design of a quad-band WLAN and WiMAX antenna was also performed. The quad-band antenna operated in the 2.4 GHz, 5.2 GHz and 5.8 GHz WLAN bands as well as the 3.5 GHz WiMAX band. The antenna had an overall size of 80×80×10.01 mm3 with an average gain of 9.3 dBi across the WLAN and WiMAX frequency bands. The antenna also achieved a directional radiation pattern with a front-to-back better than 22 dB in the WLAN and WiMAX bands. The simulated and measured results for both antennas were compared and have a good agreement. The results achieved by the proposed triple- and quad-band antennas exceeded the performance of other high gain and directional WLAN antennas found in the literature. Comparing the results of the quad-band antenna with a strip-slot antenna found in literature, the overall volume and average gain has improved by 34.7% and 2.2%, respectively.