Influence of antenna matching circuits on the measurement error of radionavigation parameters in medium-wave systems with multipath signal propagation

Objects located in the immediate vicinity of the antenna, i.e., within its near-field region, can cause significant distortions in both the amplitude and phase radiation patterns in the far-field region. Furthermore, these distortions are frequency-dependent. Thus, the use of the medium-wave band for radionavigation is associated with distortion of the radio channel's frequency response. Additionally, matching circuits used to match the reference station antenna to a 50-Ohm load can also introduce frequency distortions into the radio channel characteristic. Ultimately, the frequency response of the distorted radio channel will affect the estimation of radionavigation parameters, such as code pseudorange and carrier-phase pseudorange, due to the frequency dependence of the amplitude and phase of the received signal. Therefore, the objective of this work is to investigate the influence of matching circuits on the estimation of radionavigation parameters.