A Wide-Band Dual-Polarized Frequency-Reconfigurable Slot-Ring Antenna Element Using a Diagonal Feeding Method for Array Design

A reconfigurable slot-ring antenna that can switch between S- and C-band is presented. By turning on the eight PIN-diode switches, an S-band slot-ring antenna can be reconfigured into a 2×2 C-band slot-ring antenna array. This antenna operates from 2.75 to 4.1 GHz in the S-band state and from 5.5 to 8.1 GHz in the C-band state. In the C-band state, a diagonal feeding method is used to excite the 2×2 array and is able to provide either vertical or horizontal polarization; this feeding method can avoid the mutual coupling between two ports for V- and H-polarization.