New Accuracy Testing of the Lightning VHF Interferometer by an Artificial Intercloud Pulse Generator

The authors have rearranged an optimal method for signal processing of interferometric measurements, based on the angle-of-arrival estimation approach, and have analyzed errors of estimating the direction of arrival of intercloud pulse signals. The method was then implemented in the performance of optimized interferometer hardware. This article presents application of an array of plate antennas matched by the 50 Ω parallel resistor that are directly connected to 50-Ω high-frequency low-noise amplifiers for each channel. The important contribution of the authors is to cover the plate antenna capacitance to the input bandpass filter. The proposed compensation enables to reduce linear distortion of the received signal, which is one of the main sources of errors of the time-of-arrival estimation, and to optimize the antenna impulse response. The novelty of this article can be seen in the application of the artificial intercloud pulse generator for testing, precision calibration of the proposed system, and fixing of potential imperfections and losses in both hardware and processing software. The practical application of the proposed interferometer is demonstrated on the processing of real lightning events. As the interferometer operates in the frequency bands that are dedicated to other radio communication services, this article provides results for measurements of interference that were realized with the aim of finding an optimal installation location.