HOMOM/PE Hybrid Algorithm Based Calculation on Ground-Wave of the HF Antennas over Irregular Terrain

Abstract

The parabolic equation model usually uses a gaussian pattern to fit the actual antenna’s pattern in free space to set the initial field, and then uses the image theory to deal with the effect of ground on the antennas. However, this method of setting the initial field cannot consider the specific HF antenna, and the image theory is only applicable to the radio wave propagation of antennas working in the microwave bands and above. The HF antenna is erected low, and the irregular terrain or the buildings around the antenna and their media parameters will affect the current distribution on the antenna, resulting in a large difference with the radiation pattern in the free space. The traditional method of fitting the pattern is no longer accurate. Aiming at the problem of radio wave propagation of HF antennas in the actual installation environment by parabolic equation method, a hybrid algorithm based on higher order-method of moment and parabolic equation method (HOMOM-PE) is proposed. The hybrid algorithm divides the whole calculation region into two regions, which is the inner zone and the outer zone. The inner zone is the zone that has a great influence on the antenna current distribution. In this area, HOMOM is used to model the antenna and the terrain together, and the influence of the complex terrain near the antenna on the antenna is strictly calculated. The PE algorithm is used to calculate the long-distance propagation, and the initial field data is derived from the electromagnetic vector distribution calculated in the inner region. The hybrid algorithm combines the antenna radiation and the wave propagation directly, which solves the problem of the initial field setting of the actual HF antenna under the complicated terrain conditions.