Gain Equalized Three Antenna Pattern Diversity Module for Wlan Access Points

Abstract

This paper demonstrates a three-port coaxial fed antenna system for wireless local area network (WLAN) access points, consisting of two dipoles and a patch, radiating at 5.2 GHz with impedance bandwidth of 150 MHz. The antennas are designed for pattern diversity in the end-fire and broadside orientation with an individual gain of 4.5 dBi, which is further enhanced to 6 dBi after integrating with unit-cell structures. The gain enhancement for individual antennas is achieved by strategically integrating transmission type and reflective type sub-wavelength structures for patch and dipoles, respectively. The realized ground plane is shared among the three antennas. The measured results show that the return loss of the antennas is unaffected by the unit-cell loading and has an isolation of less than 26 dB throughout the band and across the ports for a port-to-port distance of 0.25λ.