A Small-Scaled Super Wideband Circular Ring Fractal Antenna with High BDR for SHF Applications

This paper presents a miniaturized super wideband (SWB) antenna that has a high bandwidth dimension ratio (BDR). It is intended for the use in microwave and millimeter-wave (mmWave) frequency applications. The designed antenna ensures low-dispersive behavior for both near- and far-eld performance. The radiating element is composed of three circular rings that are interconnected by conical-shaped metal strips which lead to a fractal geometry. The design incorporates a partial ground plane and two parasitic patches located at the bottom and top sides of the substrate, respectively. The parasitic strips serve the purpose of enhancing impedance matching at lower frequency bands and reducing spurious radiation that may arise from the feed line. The proposed antenna has an overall size of 20×20mm2 and exhibits an impedance bandwidth (IBW) of ≈ 57 GHz, spanning from 2.86 to beyond 60 GHz with a fractional bandwidth (FBW) of 181.8%, a ratio bandwidth (RBW) of 21: 1, and a BDR of 5036. Furthermore, the peak gain value is observed to be ≈ 11 dBi, while the average gain within the operating range is ≈ 6 dBi. The proposed antenna design was also fabricated and tested, and experimental results show a reasonable agreement with the simulated data. This makes the antenna extremely suitable for energy harvesting applications in future fth-generation (5G) and sixth-generation (6G) networks.