Semi Anechoic Chamber (SAC) and Fully Anechoic Room (FAR) or Fully Anechoic Chamber (FAR) are the two well known EMC test chamber types. What are the differences between them? Mainly there are two differences between these two chamber types:
1. Floor/Ground Plane
2. RF Absorbers
3. Dimensions
1. Floor/Ground Plane:
SAC has a ground plane on the floor while FAR/FAC’s floor is non-reflective plane. Floor of FAC is mostly covered by ferrite tiles or/and RF absorbers depending on the frequency range.
2. RF Absorbers:
SAC’s inner five surfaces covered by RF absorbing materials. The only surface which is not covered by RF absorbers is floor since reflective ground plane is needed. FAC/FAR’s all six inner surfaces are covered by RF absorbing materials to create a fully anechoic chamber.
3. Dimensions:
SAC’s dimensions are mostly larger than the FAC/FAR’s dimensions due to reflections. SAC is mostly used for emissions tests wheras FAC/FAR is used for immunity tests.
How to convert a SAC to FAR/FAC?
You can convert a SAC to FAR/FAC by adding RF absorbers to ground floor. If the RF absorbers are moveable you can use a single anechoic chamber as both SAC and FAR/FAC.