As technology advances, electronic products reach deeper into every aspect of our lives and ever larger equipment enters the market, making conformity testing for such products increasingly important.

The 10 metre semi-anechoic chamber at NTEK Group in Shenzhen is now in operation. It can test industrial and consumer products including large wireless equipment, energy storage equipment, charging piles, photovoltaic equipment, automotive components and complete vehicles.

Features of a 10 metre chamber

A 10 metre semi-anechoic chamber is designed mainly to meet the test needs of large equipment. Its features are:

★ A very large turntable diameter and high load capacity, allowing heavy samples such as industrial power supplies, energy storage converters, vehicles and large medical equipment to be tested.
★ A very large quiet zone. Compared with a 3 metre chamber, the quiet zone can be expanded to 5 metres or more.
★ Low site reflection at low frequencies down to 30 MHz.

Why a 10 metre chamber is needed

Companies choose a 10 metre chamber for two main reasons: the size of the sample, and the national certification requirements for different products. Some regions, for example, prefer 10 metre results for radiated disturbance below 1 GHz.

Disturbance measurements from 30 MHz to 1 GHz usually use a log periodic antenna, whose typical 3 dB beam width is about 60 degrees. At a 3 metre distance the illuminated width is 3.5 m, while at 10 metres it is 11.6 m, so the 10 metre distance clearly covers larger samples.

Radiation pattern of the VULB 9168 log periodic antenna

Electromagnetic radiation from a sample propagates through space as a field, and electromagnetic fields are divided into near field and far field. From a product perspective the far field is preferred: in the far field the electric field, the magnetic field and the direction of propagation are mutually perpendicular and amplitude falls linearly with distance. Near field relationships are complex and amplitude varies nonlinearly with distance, and near field results are easily affected by wave phase. The boundary between far and near field is generally at d = λ/2π, where d is the distance between measurement point and field source and λ is the wavelength. Below that distance is the near field, above it the far field.

For a 3 metre method, therefore, frequencies below 300 MHz are near field and above 300 MHz far field. For a 10 metre method, frequencies below 100 MHz are near field and above 100 MHz far field.

Both 3 metre and 10 metre chambers are common EMC test environments, but different countries and regions may have different test standards and regulations. The choice of method therefore depends on the specific product and target market.

Capability of the NTEK 10 metre chamber

Power supply: DC 1500 V 400 A times 3, 900 kW; AC 690 V 500 A times 3, 900 kW
Turntable: 6 m diameter, recessed, load capacity 6000 kg
Sliding door: 3 m by 3 m
LRC load: 600 kW
Radiated immunity: 20 MHz to 1 GHz at 30 V/m; 1 GHz to 6 GHz at 20 V/m, at 3 m
Radiated disturbance: 9 kHz to 18 GHz
Liquid cooling: 30 kW
Channels: 4 channels, 2 in and 2 out
Coolant flow: 20 to 30 m³ per minute
Temperature range: 10℃ to 25℃

Standards covered include GB/T 34133-2023, GB/T 18487.2-2017, GB 34660-2017, YY 0600.3-2007, IEC/EN 61000-6-3, IEC/EN 61000-6-4, CISPR 22 and EN 55022.

NTEK advantages

As a national high tech enterprise and a comprehensive public testing platform for intelligent connected vehicles, new materials and electronic products, NTEK provides quality research and technical services covering market access, test verification, failure analysis and simulation for intelligent communications, new energy vehicles, rail transit and aviation components.

NTEK's smart energy division has a complete testing capability for photovoltaic, storage and charging products and aims to provide one-stop testing and certification services. Capability covers electromagnetic compatibility, electrical safety, electrical performance, environmental and mechanical reliability, communication protocols and interoperability, and grid connection.

NTEK can also provide on-site testing, assessment and operation and maintenance services for operators of electric vehicle charging stations. EMC testing can be carried out in the laboratory or on site at the customer's premises. On-site EMC testing solves the problem of very large or fixed samples that cannot enter the laboratory and avoids the risk of transporting samples.