A High-Gain Tri-Band Patch Antenna With Two Independent Frequency-Reconfigurable Bands

A high-gain tri-band patch antenna with a simple structure is proposed in this letter. The first two frequency bands of the three are independently tunable by controlling four varactor diodes, providing a wide tuning range. In this case, the first frequency-reconfigurable band is generated by connecting a pair of rectangular patches and a T-shaped patch using two varactor diodes. To introduce an additional resonant mode, two L-shaped stubs connecting another two varactor diodes are added to the pair of rectangular patches, thereby creating the second tunable frequency band. The third one is fixed and excited by the pair of rectangular patches. An antenna prototype is designed, fabricated, and measured as an evaluation example. The results reveal that the independent frequency adjustable capability of the first two frequency bands covers from 2.42 GHz to 3.13 GHz and from 3.03 GHz to 4.42 GHz, with relative tunable bandwidths of 25.6% and 37.3%. The third one operates at 5.2 GHz. The peak gains of 8.8 dBi, 6.0 dBi, and 8.1 dBi are achieved within the three frequency bands.