Design of a Quad-Band Microstrip Antenna Using AMC Reflector to Achieve Gain Improvement

In this paper, a quad-band microstrip antenna is designed by adding some narrow strips on the patch and some notches on the ground acting as resonance paths to realize multi-band. The bandwidth of the antenna covers the 2.4/5.8-GHz WLAN frequency bands and the 2.5/3.5-GHz WiMAX bands. To improve its performance, an artificial magnetic conductor (AMC) characterized with four zero-phases in the reflection coefficient is proposed. The zero-crossing phase points of the AMC correspond to the antenna's operating frequencies. Splicing the AMC unit into a 5*5 matrix and placing it under the antenna as a reflector, the measured antenna gains have been improved by 5.91, 2.7, 3.0, 5.4dB respectively.