Effects of the ground plane size on radiation pattern of reconfigurable slot-ring antennas

In general, the radiation pattern of an antenna array can be predicted by the array factor and the radiation pattern of the array element. However, the radiation pattern of a reconfigurable slot-ring antenna varies with ground plane size. To explore the reconfigurable slot-ring antenna array performance, the effects of the ground plane size on radiation pattern of the reconfigurable slot-ring antenna is studied herein. Since the geometries of the reconfigurable slot-ring antenna working at different frequency bands are similar, a single slot-ring antenna with different ground plane sizes at 6.27 GHz is studied. The number of ripples in the radiation pattern increases as the size of the ground plane increases, which are due to the edge diffraction. Both a slot-ring antenna unit cell with periodic boundary conditions and a 5×5 slot-ring antenna array are simulated in HFSS. The radiation pattern of the unit cell multiplying with the array factor agrees very well with that of the 5×5 array. It can be concluded that the radiation pattern distortion caused by the edge diffraction will not exist in array applications.