Research on HF antenna blockage effects and their alleviation.

In this paper, blockage effects on high-frequency antennas are studied and their influence on the voltage standing wave ratio, gain, and radiation patterns is analysed. By simulating different blockage effects, the relationship between the antenna and the size of the blockage is clarified. It finds that radiation patterns are usually affected more seriously than other coefficients. The impact on the pattern is greater if the size or height of the blockage is larger than half of the wavelength. Two methods relating to the modification of the angle and height of the antenna are proposed that can reduce the influence of blockage effects. These are verified using a simulation and one is further demonstrated using a practical application. [ABSTRACT FROM AUTHOR]