Frequency-Reconfigurable Antenna With Wide- and Narrowband Modes for Sub-6 GHz Cognitive Radio

This letter presents a frequency-reconfigurable antenna for cognitive radio application in sub-6 GHz 5G band. The proposed antenna consists of a wideband (WB) monopole integrated with a narrowband microstrip patch in a single-layer substrate. Two PIN diodes are employed to switch between the WB sensing mode and narrowband (NB) communication mode. Three varactor diodes are implemented on the patch to continuously tune the operating frequencies in the NB mode. The proposed antenna produces a wide bandwidth of 54.2% (3.19-5.56 GHz) for the sensing mode and a continuously tunable bandwidth of 44% (3.4-5.32 GHz) for the communication mode. Both modes present good radiation characteristics with peak measured realized gains of 6.02 and 5.37 dB, respectively.

Automated summary

This letter introduces a frequency-reconfigurable antenna for cognitive radio application in the sub-6 GHz 5G band. The proposed antenna combines a wideband monopole with a narrowband microstrip patch on a single-layer substrate. PIN diodes are utilized to switch between the wideband sensing mode and the narrowband communication mode. Varactor diodes are implemented on the patch to continuously adjust the operating frequencies in the narrowband mode. The proposed antenna offers a wide bandwidth of 54.2% (3.19-5.56 GHz) for sensing and a tunable bandwidth of 44% (3.4-5.32 GHz) for communication, both exhibiting good radiation characteristics with peak measured realized gains of 6.02 and 5.37 dB, respectively.