Measurement of vehicle antenna parameters

Abstract

Each vehicle antenna has a variety of electrical and mechanical properties that characterize it. Each one of the considered series of features evaluates the antennas from a different point of view. The electrical properties of antennas are characterized by its various energy, impedance and radiation parameters. The radiation parameters of the antenna can be objectively assessed according to the shape of its radiation - directional characteristics. The shape of the directional characteristic of the antenna is influenced by a number of interrelations between its electrical and mechanical properties. The best known relationship that affects the shape of the directional characteristic of the antenna is the ratio between its mechanical parameter - the antenna length “l” and the electrical parameter - the wavelength “λ” of the operating frequency. In the theory of antennas, it is a known ratio “l / λ”, which determines the shape of the directional characteristic of the antenna. This ratio, which shapes the electric current distribution on the antenna, can be evaluated or simulated relatively simply (but not exactly), but in practice it is very difficult (almost impossible) to measure it. The article deals with a specific approach to objective practical measurement of electric current distribution on a linear antenna in the VHF frequency band.