An EMC (Electromagnetic Compatibility) test site is a purpose-built facility where electromagnetic compatibility testing is conducted on electronic devices and systems. These tests aim to evaluate the device's capability to operate effectively within its designated electromagnetic surroundings while avoiding or enduring any form of interference.

Different test sites are used for EMC testing, depending on the specific requirements and test standards. Here are some commonly used test sites:

Open Area Test Site (OATS): An OATS is an outdoor facility located in a remote area with minimal electromagnetic interference. It consists of an open ground plane, typically covered with a conductive material like metal mesh, and is surrounded by RF (Radio Frequency) absorbing materials or fencing. OATS is typically used for emissions testing of large equipment systems.

Semi-Anechoic Chamber: A semi-anechoic chamber is an indoor test facility designed to minimize external electromagnetic interference and provide controlled conditions for testing. It consists of a shielded room with conductive walls, ceiling, and floor, covered with RF-absorbing materials. The chamber typically has a ground plane and an anechoic chamber section, which contains RF-absorbing pyramids or wedges to simulate free space conditions. Semi-anechoic chambers are used for radiated emissions and radiated immunity testing.

Fully Anechoic Chamber: A fully anechoic chamber is similar to a semi-anechoic chamber, but it provides an even greater level of electromagnetic isolation. The walls, ceiling, and floor of a fully anechoic chamber are covered with RF-absorbing materials, including RF-absorbing wedges or pyramids on all surfaces, creating a "free space" environment. Fully anechoic chambers are primarily used for radiated emissions and radiated immunity testing, where the environment is designed to minimize reflections.

Shielded Enclosure: A shielded enclosure, also known as a screen room or shielded room, is a smaller-sized facility designed to provide a controlled electromagnetic environment. The walls, ceiling, and floor of the enclosure are made of conductive materials, such as metal panels or copper sheets, to prevent external electromagnetic interference from entering and to contain internal emissions. Shielded enclosures are commonly used for conducted emissions and conducted immunity testing.

These test sites are equipped with specialized instrumentation, antennas, absorbers, and shielding materials to ensure accurate and reliable EMC testing. The specific choice of test site depends on factors such as the type of testing required, the size of the device under test, and the applicable standards and regulations.