Defected Ground–Structured Symmetric Circular Ring Antenna for Near-Field Scanning Plasmonic Applications

The study presents the defected ground structure (DGS) monopole circular ring patch antenna to utilize in wireless applications. Moreover, the design that has been proposed was configured on the FR4 substrate. Initially, the proposed antenna achieves limited gain and bandwidth. The gain and bandwidth can be increased based on the defective ground structures implemented on the ground with symmetric meander line slots presented on the lower and bottom surfaces of the antenna. The feed is integrated with four uniform circular rings on either side of the antenna. Implementing circular rings on the top surface of the antenna and meander line etched slots on the defected ground enhances antenna performance to operate at desired operating bands with the figure of merits. The proposed antenna resonates at 5.6 GHz and 8.5 GHz operating frequencies with a return loss (RL) of − 22 dB and − 33 dB, respectively, obtaining 400 MHz and 700 MHz impedance bandwidth with the reference line at the concerning 10 dB RL. The gains of the proposed antenna are 4.05 dB and 5.43 dB at two resonant bands and achieve bidirectional and semi-Omni directional radiation patterns. The surface currents are also analyzed for the proposed circular patch DGS antenna. The proposed antenna is used for the WiMAX application.