Low profile dual-band reflector antenna with dual resonant AMC

Abstract

Dual-band reflector antenna with dual resonant artificial magnetic conductor (AMC) operating in WLAN band (2.4 GHz - 2.48 GHz, 5.15 GHz - 5.35 GHz) is proposed. Generally, a flat metal sheet is used with an antenna as a reflector to increase antenna gain. Since the reflection phase of a metal sheet is 180°, the antenna should be placed λ/4 away from the reflector to avoid destructive interference of the reflected wave from the metal sheet and the radiated wave from the antenna. If AMC with 0° reflection phase is used as reflector, the antenna can be closely placed to the AMC without destructive interference. There have been researches on low profile antennas using single layer AMC having 0° reflection phase in single band. In this paper, dual resonant AMC having 0° reflection phase in dual-band is designed as a reflector of dual-band reflector antenna. The dual resonant AMC is designed by adding another metallic patch-substrate layer on the conventional single layer AMC. Dual-band dipole is also designed with parasitic elements as a radiator. The height of the dual-band reflector antenna is 0.08λ which is one-third of 0.25λ, the height of reflector antenna using PEC. In addition, improvements of both gain and front lobe to back lobe ratio are achieved as a result of using dual resonant AMC which has surface wave suppression characteristic. To demonstrate improvement of gain and front lobe to back lobe ratio, comparison between the antenna using dual resonant AMC as reflector and the antenna using PEC as reflector for dual-band dipole is presented. Measured average peak gains of fabricated dual-band reflector antenna are 5.45 dB and 7.9 dB in 2.4 GHz - 2.48 GHz and 5.15 GHz - 5.35 GHz, respectively.