Variode Enabled Frequency-Reconfigurable Microstrip Patch Antenna with Operation Band Covering S and C Bands
A frequency continuous reconfigurable microstrip patch antenna with operation band covering S-band and C-band is introduced. The antenna consists of a central rectangular patch and four parasitic patches with a symmetrical structure, connected by four varactor diodes in the middle position of the edge of each patch. With help of HFSS microwave studio simulation, results have shown that, by altering the bias voltage on varactor diodes, the operated frequencies vary continuously within a wide range from 3.29 to 4.01 GHz and 5.35 to 7.00 GHz, which cover S-band and C-band. Further measurement, which verifies the simulation by reasonable agreement, has been carried out. Besides, this frequency reconfigurable antenna maintains broadside radiation and stable radiation pattern. Specifically, the gain is basically maintained at around 4.5 dBi with the working frequency increasing from 3.60 to 7.00 GHz. Compared with other frequency-reconfigurable antennas available in previous literature, the proposed antenna has advantages of a wide frequency tuning range, high frequency selectivity, simple and stable structure, low cost, and miniaturization, which make it a promising candidate as cognitive radio and future wireless communication systems.