Application
The Fabric Electromagnetic Shielding Tester is designed to measure the plane wave shielding effectiveness of various materials, including woven and non-woven fabrics, metal sheets, coatings, metal nets, conductive films, conductive glass, and conductive medium sheets. This tester utilizes the coaxial flange testing method with a double-shield structure and a computerized transmitter-receiver system for accurate automatic data acquisition of fabric electromagnetic shielding performance.
Specification
Standards
ASTM D4935, SJ2054, GB/T23326
Power
220 / 110 V, 50/60 Hz
Technical Specifications
- Launch Frequency Range: 20 MHz – 1.3 GHz
- Frequency Instability: <1000 Hz
- Minimum Frequency Jump Interval: 1 MHz
- Launch Output Power: >13 dBm
- Receiving Power Dynamic Range: +5 dBm to -55 dBm
- Receiver Accuracy: ±1 dB
- Receiver Power Resolution: 0.01 dB
- Receiver Frequency Range: 10 MHz – 3 GHz
- Double-Shield Performance: >20 dB
- Sample Thickness: ≤5 mm
Weight
80 kg
Dimensions
950 x 550 x 510 mm (L x W x H)
Testing Method
Importance of Electromagnetic Shielding
With the rapid advancement of electronic information and communication technologies, the use of electronic devices in daily life and industries is increasing. As a result, the EMC (electromagnetic compatibility) standards for human exposure to electromagnetic radiation are becoming stricter. Concerns about the harmful effects of electromagnetic radiation on human health are growing. Electromagnetic shielding materials, including fabrics, play a vital role in attenuating electromagnetic radiation. These materials, especially those used in RF protective clothing, are essential in protecting against such radiation.
Test Specification
The Fabric Electromagnetic Shielding Tester complies with standards such as ASTM D4935 and GB/T23326, and is designed for measuring the shielding effectiveness (SE) of planar materials under normal incidence, far-field, and plane-wave conditions. This test is commonly used for measuring materials like stainless steel fiber blends with cotton, polyester, or cotton-polyester fabrics.
Test Principle
- Turn on the signal generator, set the working frequency and transmitting frequency according to the instrument’s operation flow.
- The transmitted signal from the system is received by the test window’s receiving antenna, and the receiver displays the blank field strength data.
- The instrument is then powered off, and the test fabric sample is cut to the appropriate size, placed on a special test frame, and properly connected to the shield wall.
- With the signal source system turned on, the receiving system measures the field strength after the shielding fabric attenuates the signal.
- Finally, the shielding efficiency of the fabric is calculated using a specified formula.
Measurement Error Analysis and Prevention Measures
Several factors can impact the accuracy of measurements, including material characteristics, mismatches in the transmission line path, and the dynamic range of the measurement system. Errors can also arise from environmental factors like temperature, humidity, and electromagnetic interference, which is why testing should be performed in a specially designed, standard shielding room. To minimize errors, each sample should be tested three times, and the average value should be calculated.
