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

Abstract

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-field 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 × 20 mm 2 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 fifth-generation (5G) and sixth-generation (6G) networks.

RF energy harvesters for wireless sensors, state of the art, future prospects and challenges: a review

“…However, it’s worth noting that they also exhibit limitations, including narrow bandwidth and low gain as highlighted by Patil and Gahankari [ 42 ]. To address these challenges and improve the capabilities of harvesting power on a broader scale, efforts have been directed towards the development of multi and wideband RAs and transforming the conventional into distinct geometrical configurations, such as, slotted [ 50 , 51 ], fractal [ 52 , 53 ], meandered lines [ 54 , 55 ] and circularly polarized [ 56 , 57 ] as shown in Fig. 3 .…”

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Fig. 3 Miniaturized geometries and results of various RAs developed for RFEH: a and b slotted wideband antennas [ 50 , 51 ], licensed under creative commons & Copyright (2018), with permission from Elsevier; c and d fractal wide and multiband antennas [ 52 , 53 ], reproduced courtesy of The Electromagnetics Academy; e and f meandered lines wide and multiband antennas [ 54 , 55 ], Copyright (2018 & 2016), with permission from Elsevier; g and h circular polarized ultra-wideband antennas [ 56 , 57 ], licensed under creative commons & Copyright (2023), with permission from Elsevier

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“…This unique geometry results in improving the gain (2.2 dBi), reflection coefficient (-38 dB) with miniaturized size of 1444 mm 2 . Likewise, super wideband fractal and miniaturized RA is reported [ 53 ], to target RF energy harvesting from 5G to 6G wireless communication. The developed RA exhibits a low profile of 400 mm 2 with a high gain of 6 dBi for the desired frequency band.…”

“…Nevertheless, various miniaturized strategies coupled with careful design and optimization can be embraced to achieve a harmonious balance between compact size and enhanced performances tailored to a specific application and frequency band. To utilize RFEHs for wireless sensors and IMDs, miniaturized sizes of RAs can be obtained through various techniques and geometries, such as slotted [50,51], fractal [52,53], meandered lines [54,55], spiral [108] and conformal [109]. Similarly high RAs performance, efficiency, gain, and radiation pattern can be achieved through implementation of several array elements [111], also circular polarization [112] holds worthy importance in the domain of RFEH as such devices encounter signals transmitted from unidentified and diverse sources in the environment.…”