Pcb: 10 factors affecting the index of antenna intermodulation board

Pcb: 10 factors affecting the index of antenna intermodulation board

The circuit board manufacturer, circuit board designer and PCBA manufacturer explain the 10 factors that affect the antenna intermodulation board index

The third-order intermodulation signal refers to the parasitic signal generated by the second harmonic of one signal and the fundamental wave of another signal in a linear system due to nonlinear factors.

The third-order intermodulation of the base station antenna plays an important role in the system operation. What factors will affect the intermodulation index? We need to find out the reasons from the internal and external environments.

1、 External causes

1. The Stability Influence of Intermodulation Test Instrument

The stability and reliability of the equipment itself should be determined before testing the product.

→ The simplest way is to use a good intermodulation load to test the reliability and stability of the intermodulation results after a certain period of warm-up, that is, to see whether the load test results are consistent with the previous test results under the same conditions. If they are consistent, the machine itself is OK, and the following tests can be performed.

2. Influence of intermodulation test line

The test line is a vulnerable material in the test system. The theoretical plugging and unplugging times are 500, but the actual application is far more than that. In order to save testing costs, general enterprises use it until they can not meet the use requirements. The cable is mainly damaged at the connection of cable and connector, which is easy to be considered damaged during use.

→ The method is that it is recommended to handle the cable with care during use without bending the cable and connection too much, so that the service life of the cable will be longer.

3. Internal environment

The internal environment mainly involves connecting cables and internal installation.

4. External environment

The installation position of the antenna is also one of the important factors affecting the antenna intermodulation index. For example, there are barriers in front of the antenna, especially metal billboards, lightning protection flat iron on the roof, which have a great impact on the intermodulation index.

→ It is recommended that these barriers should be avoided as much as possible during actual installation.

2、 Human factors

Some testers are not professional enough in the use process, such as: the machine warm-up time is too short, the personnel are too close to the product, the cable is bent at will, and the tightness is uncertain when tightening the cable head. These are all uncertain factors that affect the test results. The torque wrench shall be used to screw the cable head as far as possible to eliminate the influence of the above human factors, and finally more accurate results can be obtained.

5. Fixed influence of DIN7/16 cable head

In the production process, because the operation standards of production workers are different, the results of operation and mutual adjustment of different personnel for the same material will be different.

→ How to avoid it? Standardized installation tools can be used as far as possible, especially the fastening strength shall be the same and firm, so as to avoid the change of intermodulation test results during the transportation of storage boxes.

6. Influence of cable components

At present, DIN7/16 cable components are widely used in the antenna intermodulation board of the base station. When purchasing feeder components, ensure that the intermodulation index is qualified. This is the entrance link that affects the intermodulation. If the feeder components cannot pass the intermodulation, it is impossible to determine the following influencing factors.

→ The self influence and intermodulation of cable components are mainly related to the material properties of DIN head and the connection process between cable and DIN head. The intermodulation index is good and stable if the process is well controlled.

7. Influence of Solder Wire Quality

In the process of antenna assembly and welding, the quality of the solder wire used is one of the important factors that directly affect the intermodulation index.

→ Therefore, if the antenna intermodulation board has a good index, test it before purchasing the solder wire, and purchase it after confirming that there is no problem.

8. Influence of feeder junction box

The antenna feeder junction box is one of the culprits that make intermodulation impossible. The most important factor affecting the intermodulation index of the junction box is the coating on the inner surface of the junction box. In order to save costs, some suppliers have used some materials containing trace ferromagnetic components, which has led to the failure of the intermodulation index to meet the requirements.

9. Effect of fixed screw material

In the process of product development, it was found that the material of the screws, nuts and spring flat pads used to fix the antenna components was one of the important factors affecting the antenna intermodulation index.

→ The screws, nuts and spring flat pads used to fix the antenna components shall be products without ferromagnetic materials as far as possible, which can effectively reduce the impact.

10. Influence of phase shifter

The performance of phase shifter with finalized structure is closely related to the strength of the material itself and the contact surface, and also has a crucial impact on the intermodulation index of the electrically tunable antenna.

The circuit board manufacturers, circuit board designers and PCBA manufacturers explain the 10 factors that affect the antenna intermodulation board indicators.