Fully Anechoic Chamber (FAR)

Anechoic Chamber Introduction​

The fully anechoic chamber (FAR) simplifies radiated emission (RE) and radiated spurious emission (RSE) testing by requiring only turntable rotation (without antenna height adjustment as in semi-anechoic chambers), making it ideal for high-efficiency EMC testing applications. Key technical specifications and design requirements are as follows:

Key Test Parameters

Test Distance 3m or 5m (EUT to receiving antenna distance)
Frequency range Standard testing: 30 MHz ~ 40 GHz (extendable to millimeter wave bands with customized absorbers)
Low-frequency testing: Supports 150 kHz ~ 1 GHz (requires ferrite + pyramidal absorber combination)
Shielding effectiveness Low frequency (14 kHz ~ 1 MHz): ≥ 80 dB
High frequency (1 MHz ~ 40 GHz): ≥ 100 dB
Quiet zone Effective test area diameter/height: 0.8m~2.5m (selectable based on sample size)
Reference Site Attenuation (for FAR with <5m test distance) Compliance standards: CISPR 16-1-4 (GB/T 6113.104), ANSI C63.4
Deviation: Within ±4 dB (30 MHz–1 GHz)
Normalized Site Attenuation (for FAR with ≥5m test distance) Compliance Standards: CISPR 16-1-4 (GB/T 6113.104), ANSI C63.4
Deviation: Within ±4 dB (30 MHz–1 GHz)
Site Voltage Standing Wave Ratio (SVSWR) Compliance Standards: CISPR 16-1-4 (GB/T 6113.104), ANSI C63.4
Requirement: ≤ 6 dB
Influence Assessment of Radiated Emission Test Table Compliance Standards: CISPR 16-1-4, ANSI C63.4
Requirement: The influence assessment results of the radiated emission test table must be incorporated into the uncertainty evaluation of radiated emission measurements
Ambient noise level At least 6 dB below test limits

Structural Design Parameters

Chamber Dimensions 3m method FAR typical shielded enclosure:Length: 8.8m (meets test distance and quiet zone requirements)
Width: 4.6m (ensures quiet zone integrity)
Height: 4.2m (accommodates quiet zone needs)
5m method FAR typical shielded enclosure:Length: 11.8m
Width: 7.6m
Height: 7.2m (supports large antenna movement and quiet zone)
Absorbing Materials Type:Ferrite tiles (30 MHz ~ 1 GHz) + carbon-based pyramidal absorbers (1 GHz ~ 40 GHz)
Low-frequency optimization: Double-layer ferrite + pyramidal composite structure
High-frequency optimization: Absorber height 0.3~0.6m (reduces reflection, improves mmWave performance)
Shielding Structure Material: Double-layer copper or galvanized steel plates welded, with metal conductive adhesive + beryllium copper finger gaskets at joints
Shielded door: Hydraulically-driven hermetic door with integrated RF filtering and EMC sealing
Turntable and antenna system Turntable diameter: 1~2.5m, load capacity ≥ 0.5~2 tons
Antenna polarization: Automatic horizontal/vertical switching
Antenna tower: Height-adjustable

Compliance Standards

EMC testing standards CISPR 32 (GB/T 9254.1 multimedia equipment)
ETSI EN 301 489-1/17/52 (EMC requirements for wireless devices like Bluetooth headsets, routers, smartphones, tablets)
Site validation NSA (Normalized Site Attenuation) error ≤ ±4 dB (30 MHz ~ 18 GHz)
SVSWR (Site VSWR) ≤ 4 dB (30 MHz ~ 40 GHz)

Typical Applications

Radiated emissions testing for laptops and peripherals
Radiated emissions and spurious emissions testing for wireless devices (Bluetooth headsets, routers, smartphones, tablets)

 

Related Anechoic Chamber