A reconfigurable integrated 4‐port UWB and NB antenna system for cognitive radio application

Abstract

A frequency reconfigurable 4-port integrated ultra-wideband and narrowband antenna structure for cognitive radio application is reported in this article. The proposed structure comprises four distinct antennas integrated on FR-4 substrate of dimensions 42 × 42 × 1.6 mm. The first antenna, named as ANT-1, is a CPW fed UWB antenna exhibiting −10 dB impedance bandwidth from 3 to 11 GHz, which includes the FCC unlicensed band ranging from 3.1 to 10.6 GHz. The remaining three antennas, named as ANT-2, ANT-3, and ANT-4, respectively, are frequency reconfigurable narrowband antennas. Each narrowband antenna is incorporated with a varactor diode to obtain a fine frequency tuning. The first narrowband antenna (ANT-2) covers a mid-frequency band from 5.35 to 8.2 GHz. The second narrowband antenna (ANT-3) attains a lower-band from 3.1 to 5.375 GHz while the third narrowband antenna (ANT-4) achieves an upper band ranging from 8 to 10.8 GHz. Simulated transmission coefficients are less than −16 dB between the antennas. ANT-1, 2, 3, and 4 accomplish simulated maximum peak gains of 4.92, 3.4, 2.9, and 3.2 dBi, respectively. The proposed structure is fabricated to validate the simulation results. The measured reflection and transmission coefficient results are analyzed with the simulation results revealing a good matching.