Tunable Multiband Antenna with an Active Artificial Magnetic Conductor Ground Plane

In this paper, a new multiband antenna consisting of a coplanar patch antenna over an active artificial magnetic conductor (AMC) ground plane is demonstrated. The AMC ground plane, which has been proven to be very effective in the design of low profile antennas, consists of 4x4 square shaped unit cells. By connecting RF switches between adjacent unit cells, a group of four unit cells can be aggregated to a larger size unit cell. In this proposed antenna, the coplanar patch is placed 2mm above the AMC ground plane. It is observed that it is possible to use the patch to excite the AMC ground plane to become another resonant element. Moreover, operation in two more resonant frequencies can be achieved by reconfiguring the unit size of the AMC ground plane. In this way, one coplanar antenna can operate at four different bands with a simple configuration while keeping a low profile. In this work, it is shown that using the actively tuned AMC ground plane, one coplanar patch antenna can operate at 5.8GHz, 5.2GHz, 4.5GHz and 2.4GHz with a good operation bandwidth (S11<-10dB), which includes the entire required bands for WLAN 802.11a/b/g applications. The experimental and simulated results for impedance and radiation performance characterization are presented. All of the design and optimization work have been conducted using the Ansoft HFSS, which is a 3D full-wave electromagnetic field simulation software.