Design of Ultra-Wideband Antenna Based on Semi-Conformal Annular Parasitic Structure

This paper proposes a novel ultra-wideband (UWB) antenna featuring a pentagonal patch and a semi-conformal annular parasitic structure. By integrating two halved pentagonal rings with the central patch and optimizing the ground slot design, the bandwidth and impedance matching performance are significantly enhanced. The antenna is printed on a 40 mm × 40 mm × 1.6 mm FR4 substrate. The simulated results indicate that the reflection coefficient is below -10 dB within the 4.67–12 GHz frequency band, achieving a relative bandwidth of 87.3% and covering scenarios such as Sub-6G (5–6 GHz), C-band (4–8 GHz), WLAN 5 GHz (5.15–5.85 GHz), and X-band (8–12 GHz). Specifically at 5.4 GHz, S<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</inf> reaches a peak matching of -42.6 dB, and at 7.1 GHz it also exhibits excellent impedance characteristics of -31.8 dB. The antenna structure is compact and suitable for multi-band wireless communication systems. Through the current regulation of the semi-conformal ring and the coupling optimization of the ground slot, this design provides new insights for the engineering applications of ultra-wideband antennas.