Generally, antenna gain measurement methods can be divided into relative gain measurement and absolute gain measurement.In terms of specific measurement methods, it can be divided into comparison method, two identical antennas method, three antennas method, beam width method, directional pattern integration method, radio source method, etc.
The method used to determine the antenna gain depends largely on the operating frequency of the antenna.For example, for antennas working above 1GHz frequency band, free space test sites are often used to measure the antenna gain with the horn as the standard gain antenna.For antennas operating in (0.1 ~ 1) GHz band, ground reflection test field is often used to determine the antenna gain because it is difficult or impossible to simulate the free space test conditions.For aircraft (aircraft, missiles, satellites, rockets, etc.) antenna, as the aircraft is often a part of the antenna radiator, in this case, the model antenna theory is often used.According to the theory of antenna model, in addition to the requirements in proportion to choose the size, shape of the antenna and its working environment, must also be in proportion to change antenna and aircraft electrical conductivity of the conductor, while the latter are unable to realize in practice, therefore, generally only model in the direction of antenna simulation actual figure, again by the measured direction graph with direction the direction of the diagram integral method to determine the actual antenna gain.If the antenna efficiency can be determined by other methods, the actual antenna power gain can be obtained by multiplying the directional gain by the efficiency.For antennas with operating frequency lower than 0.1ghz, the gain can only be measured in situ due to the obvious influence of ground surface on the electrical performance of the antenna and the large size of the directional antenna working in this frequency band.For antennas with operating frequency lower than 1MHz, generally, the antenna gain is not measured, but the field intensity of ground wave radiated by the antenna is only measured.
If you want to get more details about antenna,pls visit https://www.ericcointernational.com/antenna/