Site Validations
EMC Test Site Validation Services
EMC Hire offers a site validation service which is not only for EMC Test Facilities but for companies that aren’t necessarily looking for an approved site but want to understand the site uncertainty to allow them to gauge the risk of the results when performing pre-compliance or in-situ compliance measurements.
What is and Why do you need to Validate a Test Site
Site validation of an EMC chamber or an Open Area Test Site (OATS) is a mandatory process that confirms the facility behaves like an ideal test environment before any actual product testing occurs.
The primary reasons for this validation include:
Ensuring Measurement Accuracy
Real-world chambers have imperfect RF absorbers that reflect signals differently at various frequencies and angles. Validation (like NSA) quantifies these reflections to ensure they don't skew test results, allowing you to distinguish between actual emissions from a device and "stray" signals bouncing off the walls or nearby infrastructure.
Regulatory Compliance
Most international and military standards (e.g. CISPR 16-1-4, ANSI C63.4, and MIL-STD-461/Def Stan 59-411) require a validated site for official certification. However, for companies performing measurements on their own test site for pre-compliance or in-situ compliance, it is extremely useful to understand the site performance, this may lead to tailoring of limits at certain frequencies to account for where the site deviates outside the validation limits.
Repeatability and Comparability
Validation ensures that if a product is tested in two different compliant labs, the results will be consistent. It establishes traceability to international standards, which is critical for global market access.
What is Required
Validating an Electromagnetic Compatibility (EMC) chamber requires meeting different technical performance criteria depending on whether it is used for commercial (consumer/industrial) or defence (military) standards.
1. Commercial Chamber Validation
- Shielding Effectiveness (SE): Measures the enclosure's ability to block external signals, typically from 9 kHz to 18 GHz.
- Normalized Site Attenuation (NSA): Validates the chamber's performance for radiated emissions between 30 MHz and 1 GHz by comparing it to an ideal open area test site.
- Site Voltage Standing Wave Ratio (sVSWR): Required for testing above 1 GHz (typically up to 18 GHz) to account for internal reflections.
- Field Uniformity (FU): Essential for immunity testing (per IEC 61000-4-3) to ensure the electromagnetic field is consistent across a 16-point grid.
2. Defence (Military) Chamber Validation: Mil Std 461
- Absorber Performance: Specifies minimum absorber reflection suppression rather than full site validation.
- Test Distance: Typically performed at a 1-metre distance in the near field.
- Ground Plane Requirements: Equipment often placed on a conductive copper ground plane.
3. Defence (Military) Chamber Validation: Defence Standard 59-411 Part 3
- Screened Room Damping Performance (no ground bench): Required for Man Worn or Portable equipment using antenna comparison methods.
- Screened Room Damping Performance (with ground bench): Correlation with OATS using Comparison Noise Emitter (CNE).
Need a Site Validation?
Contact our engineering team today to discuss your requirements.