Application, Performance and Structure of Radome Application, performance and structure of radome

A radome is a structural, weatherproof enclosure that protects an antenna. The radome protects the antenna from weather and hides the antenna electronics. The radome is made of a material that is transparent to radio waves. It has good electrical properties for electromagnetic wave penetration and mechanical properties that can withstand harsh external environments. Outdoor antennas are often placed in the open air and are directly exposed to natural storms, snow, dust, and solar radiation, which can reduce the accuracy of the antenna, shorten its service life, and reduce its operating reliability. Therefore, it is necessary to install radomes for outdoor antennas. They can also protect nearby personnel from accidental impacts with rapidly rotating antennas.

You can click this for Antesky 4.2m S/X band antenna with radome for learning the appearance of radome.

In order to protect the antenna ground station system, a radome needs to be installed when necessary. The functions of the radome are listed below:

Protect the antenna: The radome can protect the antenna from the external environment, such as rain, snow, wind, sand and dust, and extend the service life of the antenna.
Reduce damage: When the antenna is hit by external force, the radome can absorb part of the impact force or even sacrifice itself to protect the antenna from damage.
Reduce wind resistance: The design of the radome can reduce wind resistance, reduce the resistance of the airborne antenna, and improve the stability of the antenna.
Electromagnetic wave transmission: The radome material usually has good electromagnetic wave penetration, allowing electromagnetic waves to pass smoothly, while having little effect on the radiation pattern of the antenna.
Aesthetics: The radome can makeappearance of the antenna more beautiful and coordinated with the surrounding environment.
Concealment: In some applications, the radome can be used to hide the antenna to reduce the visual impact on the surrounding environment.
Prevent interference: The radome can reduce the interference of the antenna to other electronic devices, and also reduce the interference of other devices to the antenna.
Heat dissipation: In some high-power antenna systems, the radome can also help dissipate heat and maintain the normal operating temperature of the antenna.

When designing, manufacturing and producing the radome, its component size, thickness, material selection, structural details, etc. will be strictly considered.

First, the thickness of the radome must be designed according to the working wavelength to reduce reflection, and it must be able to withstand various loads without deformation;

Secondly, the material of the radome must be very particular. Common materials used for radomes include fiberglass, plastic(ABS, PC, ASA, etc.), or composite materials. Glass fiber with good transmittance is a good choice as the main material;

Third, in order to facilitate manufacturing, installation and transportation, large rigid radomes will be made into football-like blocks, and the spherical joints must pass electrical performance tests and structural performance tests.

Antesky 4.2m S/X band antenna radome assembling on site

According to the structure, there are three types of radome like single-layer, sandwich and metal-containing functional structure. The single-layer wall uses only one material and has the simplest structure. In order to reduce losses, the single-layer wall radome can adopt thin-wall and half-wave wall thickness structures. The radome with sandwich structure can provide higher structural strength, and the appropriate layer thickness ratio can also provide excellent wave transmission performance. The sandwich wall includes A sandwich, B sandwich, C sandwich and multi-sandwich structures. The metal-containing structure is divided into reactance loading structure and frequency selective surface structure.

The specific radome layer structure is shown in the figure below. Among them, the A sandwich is a two-layer high-strength skin structure sandwiching low-loss, low dielectric constant, and low-density material. The B sandwich structure is just the opposite. The C sandwich and multi-sandwich structures use more layers of materials, and their main purpose is to improve the structural strength of the radome.

Figure 1 Antenna radome layer structure

Single-wall radomes are usually made of fired ceramic materials or stretched and laminated resin fiber materials. The half-wave wall adapts to a wide range of incident angles, has a stable insertion phase, and is insensitive to polarization. The disadvantages of the half-wave wall are narrow bandwidth and sensitive wave transmittance to changes in the incident angle. The half-wave wall usually has a high material density and high structural strength, so it is often used in the hoods of fighter jets or missiles.

The thickness of a thin-walled radome is usually less than 1/20 of the working wavelength, with light weight and good electrical properties, but poor mechanical strength.

The A sandwich radome consists of two layers of skin, inner and outer, and a core layer in the middle. The high-strength skin can resist impact, the core layer can resist torsion, and the low-density core layer has a large thickness, so the overall weight of the radome is low. The dielectric constant of the skin is higher than that of air, so the reflection is also larger. The reflection of the skin can be offset by a suitable thickness ratio, thereby achieving high wave transmittance.

The figure below shows the curve of the wave transmission loss of the Ka-band A sandwich radome as the core thickness changes. It can be seen that the optimal loss of the radome does not occur when the core thickness is 0. The first optimal core thickness for wave transmission is about 1.5mm, and the second optimal thickness is about 5.5mm. The size and strength requirements of the radome should be considered in the design of the radome, so as to find the optimal core thickness from the peak points of the curve in the figure below.

Figure 2 Curve of the transmission loss of interlayer A versus the thickness of the core layer

The B sandwich radome consists of two layers of low dielectric constant materials sandwiching a high dielectric constant material in the middle. Reasonable design can make its electrical performance better than the A sandwich structure, but its mechanical strength is often poor, so it is not often used.

The C sandwich radome consists of three layers of skin and two core layers, with good mechanical properties. The multi-layer structure can expand the working frequency band. However, the C sandwich structure has complex process, poor manufacturing repeatability, and poor insertion phase performance.

The multi-layer sandwich radome is an upgrade of the C sandwich. It is composed of many materials with different dielectric constants and has a wider bandwidth. It is generally used in electronic countermeasure radomes.

There are two technical routes of radomes containing metal objects: reactance loading and frequency selective surface. Reactance loading is to arrange metal objects in a certain way and direction and add them to the conventional wall structure, so that the radome has special electrical properties in a certain frequency band. The frequency selective surface is a three-dimensional structure of a single-layer or multi-layer surface composed of units arranged in a two-dimensional periodic manner. Electromagnetic waves in a specific frequency band can penetrate the radome, while scattering other frequency signals to other directions, thereby achieving stealth against the enemy while ensuring the normal operation of its own radar.

The above is the brief introduction of radome material selection and radome design. We hope that this will be helpful to all users who is in need of antenna radome in the future. If you have any related questions, please feel free to consult us. Antesky is professional antenna suppliers in China for years. If you are looking for satellite communication antennas and accessories, please contact by sales@antesky.com. or you can WhatsApp us directly. we will offer you high quality antenna with the best price.