A satellite horn antenna is the simplest type among all kinds of antennas. Compared with the parabolic antenna, the waveguide area of horn antenna is very small, so the gain and directional effect of the antenna are also very small. If the antenna is used to receive satellite signals, its antenna gain should be at least 34 dB/ll.3 GHz According to the calculation, to meet the gain requirement, the required edge length of the horn antenna is 52 cm×52 cm, and the structure length is 80 cm. Because of the high processing cost of waveguide horn antennas, it is obviously impractical to use a horn satellite antenna to receive satellite signals, so people often use it for directional radio testing or as the feed system of a reflector antenna. When the horn is used as the feed of the reflector antenna, there are many structural types, but most of them are annular or conical. Moreover, the double-ridged waveguide horn antenna is also widely used for EMI testing, surveillance equipment, antenna gain and pattern measurement.
Plane antenna, also known as flat antenna, is characterized by good reception performance and small size, which is especially suitable for home use. The structure of planar antenna is very complex, and the requirements of technology and accuracy are also very high when making it. Its overall structure is multi-layered sandwich, mainly including two panels, two thin plates with holes, a dielectric carrier membrane and a reflector. The main part of the antenna is composed of many dipole antennas and distribution networks. During fabrication, hundreds of t/4 dipoles are placed on the dielectric carrier film by etching process. These dipoles have regular transverse and slit shapes on the diaphragm. Then, a dielectric carrier film is placed between two porous thin plates. During production, the requirements for the smashing between the plate and the wrench are very accurate. Finally, the reflector is placed behind the diaphragm at a distance of A/4, and the control of each single dipole antenna by the flat antenna is realized by the distribution network. In this distribution network, the amplitude and phase of the signal are gathered accurately, which is very important for the flat antenna.
A typical reflector antenna consists of a feed horn and a paraboloid of revolution. The feed source is placed in the focus of the metal reflecting surface, and the focused high-frequency energy is fed to the receiving device through the waveguide. This antenna is characterized in that it can be made into any size according to the need of frequency range. Generally speaking, the quality of the reflecting surface and the accuracy of the equipotential line can influence the antenna gain and efficiency, especially the accuracy of the equipotential line is not allowed to have any deviation, otherwise, the focus will move. For the receiving antenna, the focus offset means that all the high-frequency energy reflected by the main reflector can't reach the feed system. After the loss of high-frequency energy, the antenna efficiency and gain become worse. When the diameter of the reflector antenna is 55 cm, the antenna gain can reach 34 dB.
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