1. The mechanical properties of the antenna:
The mechanical properties of antennas produced by different manufacturers are different. This requires that the mechanical performance requirements of the antenna are clearly defined in the design of the microwave circuit, so that a suitable antenna can be selected. For example: Antennas installed in different regions have different requirements for the mechanical performance of the antenna. Coastal circuits have put forward more stringent requirements on the wind resistance index of the antenna.
A. Antenna wind resistance
Working wind speed: At this wind speed, the axial deflection angle of the antenna is less than one-third of the half power width of the highest frequency point. For example: Putian antenna working wind speed index is 35m/s. Limit wind speed: At this wind speed, the antenna The system will not show any permanent deformation, for example: Putian antenna's limit wind speed index is 55m/s.
B. Antenna hanger adjustment range
The horizontal azimuth adjustment range is 360 degrees for coarse adjustment, and fine adjustment for a 2m diameter antenna is generally ±5 degrees. This index is related to the antenna diameter. .The pitch fine-tuning range, the diameter of 2m antenna is generally 5 degrees. This index is also related to the antenna diameter. .
C. Ice thickness:-generally 25mm. This indicator is very worthy of attention in cold and humid areas.
D. Operating temperature: The general operating temperature of the antenna is 55C-+70C.
E. Antenna system weight: This index is very important for the transportation and installation of the antenna. This index is needed in microwave design to determine whether the load capacity of the tower or pole meets the requirements. .
F. The requirements of the antenna on the pylon for the pole: Because the antennas of different specifications are suitable for poles of different diameters, the appropriate pole should be configured according to the requirements of the antenna pylon.
2. The electrical performance of the antenna
The electrical performance of antennas produced by different manufacturers is different. This requires that the electrical performance requirements of the antenna are clearly defined during the design of the microwave circuit, so as to facilitate the selection of a suitable antenna.
A. Frequency: Refers to the frequency band used by the antenna. These frequency bands generally conform to the universal standards.
Microwave equipment of different manufacturers may choose different frequency division methods, so it is necessary to select a suitable antenna corresponding to the specific antenna frequency.
B. Standing wave ratio: refers to the maximum voltage standing wave ratio of the antenna in the frequency band used. The standing wave ratio reflects the reflection of the antenna system to the signal and is a very important electrical index in the microwave system. The standing wave ratio index of the antenna and the system standing wave index after the antenna feed system is connected must meet the requirements of the circuit design. The defects in the manufacturing process and the damage in the device installation process will reflect the change of the standing wave index. Therefore, the electrical performance of the device or system can be judged by the standing wave ratio index.
C. Antenna gain: refers to the gain of the antenna at the center frequency of the frequency band used, the unit is dBi (point source). The sampling antenna is tested according to the frequency of use at three points: high, medium, and low, and then the average value is the antenna gain. The specified gain error is 0.2dB. In a dual-polarized antenna, the gain refers to the gain of the front port, and the gain of the rear port is generally 0.2dB lower than the front port. The antenna gain increases as the antenna diameter increases.
D. Front-to-back ratio: refers to the ratio of the antenna main lobe level to the back lobe level, in decibels. The back range of the high-performance antenna front-to-rear ratio is 180°±70°, and the back range of the standard antenna is 180°±45°
E. Half power angle: refers to the lobe width when the antenna power drops by 3dB. The half power angle reflects the directivity index of the antenna. As the diameter of the antenna increases, the directivity of the antenna becomes better, and the frequency interference between adjacent circuits is correspondingly reduced.
F. Cross-polarization discrimination rate: refers to the level ratio between the main polarization and the cross-polarization of the antenna in the half-power angle range. The unit is: dB.
G. Isolation: Isolation is mainly for dual-polarized antennas, unless otherwise required, the minimum isolation of dual-polarized antennas is 35dB.
H. Antenna radiation envelope: It is an important indicator reflecting the overall electrical performance of the antenna.
I. Flange interface type: The antenna flange interface type needs to match the microwave equipment or waveguide feeder interface. Generally, the antenna flange interface is PDR.