Frequency Continuously Tunable Patch-Slot Antenna With Wide-Angle Discrete Scanning and Optional Backward Radiation

A novel frequency continuously tunable patch-slot antenna with wide-angle discrete scanning performance and one optional backward radiation state is presented. This antenna originates from combining one patch antenna with two endfire radiation slot antennas. By loading varactors on the patch, the working frequency is continuously adjusted, and simultaneously the maximum beam direction could be reconfigured by controlling four PIN diodes located on two slots. The proposed antenna is capable of reconfiguring its maximum beam direction to six discrete angles at 0°, -36°, -78°, +36°, +78°, and 180°. A prototype is fabricated and measured to validate the design, and experimental results demonstrate that the antenna has the merits of both wide-angle beam discrete scanning performance of ±78° in the H-plane and switchable backward radiation feature within frequency tuning range of 2.24-2.58 GHz.