The radome mainly has five structures: aviation radome, ground radome, inflatable radome, shell structure radome and space skeleton radome.
folding aviation radome
Generally, it is a shell structure. Depending on the specific situation, a normal-incidence radome or a streamlined large-incidence-angle radome can be used. In order to meet the requirements of aerodynamics, the radome should be made into a streamlined structure. However, when the antenna is scanned in the radome, the incident angle changes greatly, making it difficult for the radome to obtain the best electrical performance. If not streamlined, the radome is usually designed with an incident angle of less than 30°, and its shape can be cylindrical, spherical or parabolic. The aerodynamic performance of this vertical incidence radome is poor, but the electrical performance is good.
Folding Ground Radome
Usually truncated spherical (about three-quarters of the ball), can be divided into two types of inflatable cover and rigid cover. Rigid radomes are further divided into shell structure radomes and space skeleton radomes.
Folding inflatable radome
The spherical film is fixed on the air-tight platform with a pressure plate around the cutout, and the surrounding area is tightened with ropes, or fixed by other methods, and the interior is inflated. Its advantages are that the cover wall is thin and uniform, the electrical performance is good, and it is suitable for broadband operation; the cover body is soft and easy to fold, light in weight, small in size, and convenient for transportation, storage and installation. The disadvantage is that constant inflation of the hood is required to maintain the hood shape and necessary rigidity. Failure of the inflatable device can cause the cover to collapse and damage the antenna. The United States has developed the largest inflatable hood with a diameter of 64.05 meters (210 feet), which is used as a radar antenna for a “communication satellite” (Telstar).
Folding shell structure radome
The cover wall is usually made into a curved shell, and the structural load is supported by the shell. Among them, the uniform single-wall shell structure is limited in terms of working wavelength and size, and the size of the cover is limited; the foam plastic shell structure is electrically allowed to use thicker cover walls due to the low dielectric constant and loss tangent of the material. Structural load requirements. The connection between the foam blocks can be glued together to form a uniform overall shell, which has good electrical performance and is suitable for high-frequency and wide-band work; the sandwich shell structure is usually A-type sandwich structure. It consists of two equal-thickness symmetrical high-strength-density skins and a low-density core. Its advantages are large strength-to-weight ratio and stiffness-to-weight ratio, and it is suitable for large ground radomes of certain wavelengths. But the disadvantage is that the working frequency is narrow, the manufacturing is complicated, and the cost is high. When the A-type interlayer cannot meet the requirements, a multi-layer interlayer structure composed of odd-numbered layers can be used. The 44.4-meter-diameter sandwich radome successfully developed in China in 1972 adopted the A-type sandwich shell structure.
Folding space frame radome
It is composed of a metal (or dielectric) spherical grid skeleton and a dielectric sheet (or film) cast on it. The structural load is mainly carried by the grid skeleton. The design principle of the grid skeleton is to make the electrical shielding of the bar section as small as possible while ensuring the mechanical properties. The strength and stiffness of metal are greater than that of dielectric materials, so metal skeletons are often used. Its advantages are that it is suitable for high-frequency and wide-band work, easy to manufacture, relatively cheap, and suitable for large-scale ground antennas. The world’s largest metal space skeleton radome was built in 1964 and has a diameter of 45.75 meters (150 feet) for the US Haystack radar antenna.