1. First of all, we must understand the purpose of using a shielded box: one is to limit the radiated electromagnetic energy inside the equipment from going out of a certain area; the other is to prevent external radiated electromagnetic energy from entering a certain area.
2. The shielding effectiveness of the shielding box: when the simulated interference source is placed outside the shielding box, the ratio of the electric field strength, magnetic field strength or power at a certain point in the space before and after the shielding box is placed and then take the logarithm (lgp1/p2), expressed in dB .
3. Shielded box test equipment: network analyzer (signal generator + spectrum analyzer), dipole antenna, horn antenna, shielded box.
4. The specific function and application scope of the shielding box:
For manufacturers of wireless communication products, the failure of the products to be available on the market in time or to sell quickly will result in the loss of a large amount of output value and profits, which will directly affect the subsequent expansion of business and market share.
The RF test process is usually the most complicated and influential process in the production line of wireless communication equipment such as mobile phones, and it is usually the bottleneck of the production line. The radio frequency test station is usually composed of several parts such as test instrument, shielding box, test software, etc., and usually can be divided into calibration test, comprehensive test, antenna test and so on. Due to production capacity requirements, the RF test process is usually run in parallel by multiple identical test stations. The pass rate of one or some test stations is low; lower output will lead to bottlenecks in the production line and a sharp increase in production costs. The reasons can be roughly divided into: product design or material reasons, and test problems (errors). Test problems), environmental factors such as radio frequency interference, and uncertain problems in the test.
5. Classification of shielding boxes
The shielding box can be manufactured into different working modes such as manual, pneumatic, and fully automatic according to different test requirements. The fully automatic shielding box completes the entire test process by controlling the test shielding box through the international standard RS232 interface according to communication instructions. Generally, it is used for small-scale radio frequency modules and large-scale production lines to improve production efficiency. The manual shielding box is generally small in size and convenient to operate. It is currently the most commonly used one on the production line of small communication equipment such as mobile phones. There are also some parts that are too large and inconvenient to use pneumatic operation, but also use manual door guarding. Pneumatic shielding boxes are generally large in size, in order to improve the test efficiency and reduce the fatigue of the operator in the production test.