With the rapid development of electronic information and communication technology, electronic devices are used in people’s daily life and industrial fields more and more. At the same time, the EMC standard of limits for personnel exposed to electromagnetic radiation is becoming more and more strict, and the public pays more and more attention to the harm of electromagnetic radiation to the human body. At present, many kinds of electromagnetic shielding materials have been developed, electromagnetic shielding fabrics are widely used to attenuate electromagnetic radiation, especially the production and manufacture of RF protective clothing. So how to test these protective clothing?

Test Specification

Fabric Electromagnetic Shielding Tester is used to test the plane wave shielding effectiveness of materials, in accordance with the standard ASTM D4935 and GB/T23326 and so on. This test method applies to the measurement of SE of planar materials under normal incidence, far-field, plane-wave conditions. This test standard applies to the measurement of stainless steel fiber blended with cotton, polyester or cotton polyester.

Test Principle

Turn on the signal generator according to the operation flow of the instrument and adjust the working frequency and the transmitting frequency. Well, the signal transmitted by the system through the transmitting antenna is received by the receiving antenna of the test window and the data displayed by the receiver is blank field strength. Shut down the instrument, then cut the test samples of the screened fabric to the appropriate size, fixed on the special test frame, and keep good contact with the shield wall. Turn on the signal source system according to the above parameters. At this time, the receiving system will receive the field strength after the attenuation of the shielded fabric. Finally, calculate the shielding efficiency of shielding fabric according to the formula.

Measurement Error Analysis and Prevention Measures

The uncertainty of the measured result is a function of material, mismatches throughout the transmission line path, dynamic range of the measurement system, and the accuracy of the ancillary equipment.

Test system error: The test error generated by the test instrument and the supporting system, which has been effectively controlled in the instrument design, the fitting selection, and the calibration.

Environmental impact error: The errors due to humidity, temperature, and electromagnetic field interference in the environment. Therefore, the measurement work should be carried out in a standard shielding room with specially designed.

Sample placement error: The error caused by the difference between the position of the test sample and the relative position between the shielding chamber and the sample. When testing, keep the relative position unchanged, at the same time, test each sample is three times, and calculate the average.