4G Fiberglass Antenna Radiation Pattern Details

　　Detailed explanation of 4G fiberglass antenna radiation pattern

　　Basic concepts

　　The 4G fiberglass antenna radiation pattern, also known as the radiation pattern, depicts the relative field strength (normalized modulus) of the radiation field changing with direction at a certain distance from the antenna. It is usually represented by two mutually perpendicular plane patterns in the direction of maximum radiation of the antenna, which are the horizontal plane pattern and the plumb plane pattern. This allows an intuitive understanding of the radiation characteristics of the antenna at different spatial angles. It is essentially used to quantitatively describe the strength of the antenna's directivity, defined as the ratio of the power density of the antenna at a point in the far area in the direction of maximum radiation to the power density of the non-directional antenna at the same point with the same radiation power.

　　Common radiation pattern types

　　Omnidirectional radiation pattern: Among 4G fiberglass antennas, some models have omnidirectional radiation characteristics, such as some omnidirectional fiberglass antennas used for open area coverage. Its horizontal radiation angle is 360 degrees, and the signal radiates evenly in all directions on the horizontal plane, which is suitable for signal coverage of all-round areas around. However, in the vertical direction, it is not uniformly radiated, but fan-shaped, with a vertical angle of about 6-15 degrees. The higher the gain, the smaller the vertical angle. For example, for an antenna with a 9dB gain, the vertical radiation angle can be about 14 degrees, while an omnidirectional antenna made of fiberglass can achieve a vertical angle of about 8 degrees. This small vertical angle makes omnidirectional fiberglass antennas widely used in wireless coverage of large areas such as open sea and plains. When installed at a high place (such as on the mast of a ship), the transmitted signal can be transmitted to a farther place to obtain a longer communication distance.

　　Directional radiation pattern: In order to meet the signal coverage or enhancement requirements in a specific direction, some 4G fiberglass antennas are designed for directional radiation. Its energy is concentrated in a specific direction, such as the 12dBi high-gain fiberglass antenna deployed in forest fire monitoring, with a horizontal beam width of 65° and a vertical beam width of 30°. By concentrating the signal in a specific sector area for transmission, higher signal strength and longer transmission distance can be obtained in the area, which is suitable for scenarios where the target area is clear, key coverage is required, or long-distance signal transmission is required.

　　Factors affecting the radiation pattern

　　Antenna structure design: The internal structure of the antenna, such as the number, arrangement, size, and feeding method of the radiating elements, plays a decisive role in the radiation pattern. The multi-element array design can achieve beamforming and change the shape and direction of the radiation pattern by adjusting the phase difference and amplitude ratio between the elements. Increasing the number of vibrators can allow electromagnetic waves to travel farther in the horizontal direction. Combined with the control direction of the reflector, the emission direction of the electromagnetic waves can be concentrated in a specific area, forming the prototype of a directional antenna.

　　Glass fiber material characteristics: As the outer shell material of the antenna, glass fiber does not directly participate in electromagnetic radiation, but it has an indirect effect on the radiation performance of the antenna. Its dielectric constant, loss tangent and other characteristics will affect the distribution of the electromagnetic field inside the antenna, and thus affect the radiation pattern. If the dielectric constant of the glass fiber material is unstable or the loss is large, it may cause additional attenuation or phase change of the signal during transmission, causing the radiation pattern to be distorted.

　　Surrounding environmental factors: The surrounding environment of the antenna, such as topography (mountainous areas, plains, waters, etc.), building distribution and other electromagnetic interference sources, will have a significant impact on the radiation pattern. In mountainous areas, signals are easily blocked and reflected by mountains, causing the signal to weaken in certain directions or multipath effects to appear, making the radiation pattern complicated. In cities, the obstruction and reflection of buildings will change the propagation path and intensity distribution of the signal, making the actual coverage range and radiation direction of the antenna different from the radiation pattern in the ideal state.

　　Characteristic parameters of the radiation pattern

　　Main lobe width: It is a physical quantity that measures the sharpness of the maximum radiation area of the antenna. It is usually taken as the width between the two half-power points of the main lobe of the antenna pattern. The narrower the main lobe width, the more concentrated the energy of the antenna is in the main radiation direction, the stronger the directivity, the longer the signal propagation distance and the stronger the anti-interference ability. In remote monitoring applications, such as high-gain directional fiberglass antennas used in forest fire monitoring, narrower main lobe widths ensure stronger signals in the target monitoring area, improving the accuracy and reliability of monitoring.

　　Sidelobe level: refers to the level of the first sidelobe closest to the main lobe and with the highest level, generally expressed in decibels (dB). The lower the sidelobe level, the better. Too high a sidelobe level will cause energy dispersion, which may cause unnecessary interference in other directions and reduce the signal transmission efficiency and anti-interference performance of the antenna. For 4G fiberglass antennas, the sidelobe level should be minimized by optimizing the antenna structure and parameters during the design and manufacturing process.

　　Front-to-back ratio: refers to the ratio of the level in the maximum radiation direction (forward) to the level in the opposite direction (backward), usually in decibels. A higher front-to-back ratio means that the radiation intensity of the antenna in the main radiation direction is much greater than that in the backward direction, which can effectively reduce the interference of the backward signal and improve the antenna's ability to receive and transmit signals in the target direction. In some scenarios where it is necessary to avoid rear signal interference, such as 4G fiberglass antennas installed on the exterior walls of buildings for indoor coverage, a higher front-to-back ratio can ensure that the signal is mainly radiated indoors, reducing interference to other outdoor areas.

　　Directivity: The ratio of the radiation power flux density of the antenna in the direction of maximum radiation at a certain distance from the antenna to the radiation power flux density of an ideal non-directional antenna with the same radiation power at the same distance. The larger the directivity, the stronger the radiation ability of the antenna in the direction of maximum radiation and the higher the energy utilization efficiency. 4G fiberglass antennas with high directivity have important application value in scenarios where long-distance signal transmission is required or reliable communication is achieved in areas with weak signals.