# PD Koch Complementary Fractal UHF Antenna Based on AMC Metasurface

## TL;DR

This paper introduces a new UHF antenna design using a Koch fractal and AMC metasurface to improve sensitivity for detecting electromagnetic waves from partial discharges in power equipment.

## Contribution

The novelty lies in combining a Koch complementary fractal structure with an AMC metasurface for enhanced UHF antenna performance.

## Key findings

- The antenna achieves improved voltage standing wave ratio (VSWR) and gain across low and high frequency bands.
- Average gain increases by 35.19% in the 0.3 GHz to 1.5 GHz range.
- Peak gain reaches 11.5 dB, showing a 120% enhancement.

## Abstract

To meet the high-sensitivity requirement of ultra-high-frequency (UHF) sensors for electromagnetic waves radiated by partial discharge (PD) in power equipment of substations, this paper proposes a Koch complementary fractal UHF antenna based on the artificial magnetic conductor (AMC) metasurface. First, based on the Iterated Function System (IFS), a finite element model of the UHF Koch fractal antenna is constructed via affine transformation. Then, leveraging the in-phase reflection characteristic of the metasurface, an AMC metasurface for gain enhancement of the Koch fractal antenna is designed, and a multi-dimensional parameter joint optimization method is adopted to obtain the optimal structural parameter set of the Koch fractal antenna loaded with the AMC metasurface. Finally, experimental tests and analyses are carried out on the Koch complementary fractal UHF antenna. The results show that the antenna loaded with the AMC metasurface achieves a better voltage standing wave ratio (VSWR) and improved gain in both low and high frequency bands: the average gain increases by 35.19% in the frequency range of 0.3 GHz to 1.5 GHz, and the peak gain reaches approximately 11.5 dB with an enhancement of 120%.