CO-DESIGN OF A COMPACT DUAL-BAND FILTER-ANTENNA FOR WLAN APPLICATION

A co-designed compact dual-band filter-antenna suitable to be embedded inside a wireless access point (AP) in the 2.45/5.2GHz wireless local area network (WLAN) bands is presented. The proposed filter-antenna comprises a loop-loaded dual-band monopole radiator and a microstrip dual-band pseudo-interdigital bandpass filter. The monopole consists of a uniform width monopole, two identical capacitively loaded magnetic resonators and a top loaded loop. The two magnetic resonators are loaded at the center of the monopole for dual-band operation and the rectangular loop loaded at the top is involved for miniaturization. Instead of using the traditional 50 Omega interfaces, the impedance between the filter and antenna is optimized to improve the performance. The filter-antenna and the system circuit board of an AP share the same substrate and ground plane. In this case, the design can fully integrate the circuit board of the AP into an internal filter-antenna solution. The proposed filter-antenna provides good selectivity and rejection in out of band regions and omni-directional radiation patterns within the two desired bands. The measured results show good agreement with the simulated ones.