Design and Evaluation of Finite and Small Antennas at 0.97 GHz for Lightning Remote Sensing

Abstract

This paper presents the analysis of the UHF signature associated with positive and negative narrow bipolar events (+NBEs and -NBEs) captured by using a finite antenna (the largest dimension comparable to the wavelength of the incident electric field) and a small antenna (the largest dimension less than one tenth of the wavelength of the incident electric field). Both antennas have been designed and simulated in Computer Simulation Technology(CST) simulator. The finite antenna was calibrated inside anechoic chamber and was found to have resonant frequency at 0.97 GHz with 20 MHz bandwidth and omnidirectional radiation pattern. Measurements have been conducted between November and December 2018 where 120 UHF samples and 69 UHF samples had been captured by small antenna and finite antenna, respectively, together with their corresponding low frequency records (lower than 1 MHz), also known as fast antenna record (FA record). In average, the UHF peak amplitudes of the finite antenna are 22% larger than the small antenna and the former has better SNR which would ease the characterization of the UHF signals.