Analysis of the operating conditions for UAV-based on-board antenna radiation pattern measurement systems

Communications, navigation, and other related systems need to have a well-defined antenna radiation pattern. In onboard vessel systems, the radiation pattern can be much different than the one obtained for an isolated antenna (because of the vessel’s structure and other nearby radiating systems interference). Finding out the onboard antenna’s radiation pattern is a well-known problem for any shipbuilder/owner. The conventional method consists of measuring radiation patterns from a fixed antenna on the coast while the ship is navigating in circles. Recent electronic systems in the market now allow for an alternative method: keeping the ship static while an unmanned aerial vehicle (UAV) circles it, measuring the antenna’s transmitted power. This research paper examines the airspace volume and optimal flight path of an off-the-shelf UAV system for measuring the onboard antenna’s radiation pattern in the presence of physical constraints such as the vessel’s dimensions, safety zone, distance to base, Fresnel’s and multipath distances, and considering the loss due to polarization decoupling between the antenna under test and UAV’s antenna.

Multi-channel interference source detector

Modern radars, along with the detection and measurement of target coordinates against the background of interference, must solve the problem of detecting radio emission sources and measuring their coordinates. Detection of interference, as well as targets, in the radar is provided in the main (total) channel based on the analysis of the rangefinder-Doppler portrait of the received signal. The main disadvantage of such a detector is that the interference coming along the side lobes of the sum antenna and falling into the dip of the antenna radiation pattern may not be detected. Therefore, the problem arises of developing and analyzing algorithms for detecting interference in a radar with several receiving channels. The article discusses the logical, energy, correlation and eigenvalues of the cross-correlation matrix of the received signals interference detectors for two receiving channels. Their characteristics are given. It is shown that two-channel interference detectors based on the analysis of the eigenvalues of the cross-correlation matrix have the highest efficiency. Energy and logical algorithms are quite a bit inferior to them. The developed algorithms make it possible to effectively detect radio emission sources even when they are in the dip of one of the antenna patterns.