Not every RF test requires a full-size anechoic chamber. For many specific applications, a compact shielded enclosure, properly designed for the application, can deliver equivalent or superior performance at a fraction of the cost and space.
What Is a Shielded Box?
A shielded box is a self-contained, tabletop or floor-standing enclosure with RF-absorbing interior surfaces, typically under 1.5m in any dimension. Access ports and cables enter through filtered penetrations, with test instrumentation sitting outside. A well-designed shielded box can achieve shielding equivalent to or better than a full chamber, since the compact geometry means fewer penetrations and simpler door mechanisms.
Application-Specific Shielded Enclosures
Desense Testing Box
Measures wireless receiver degradation caused by interference from a device's own processor, display, or power supply — critical for smartphones, wearables, and IoT devices. A full chamber is overkill for this device-level characterisation; a compact box provides ambient rejection in a space-efficient format.
IoT / Throughput Rate Automated Testing Box
Provides an RF-isolated environment for automated OTA throughput testing, integrating RF routing and device handling into a production-line format processing hundreds of devices per shift — something a full chamber's cycle time can't support.
Radar Simulator Compact Range Testing Box
A shaped reflector converts the transmit antenna's spherical wave into a planar wave at the DUT, replicating far-field radar conditions in a tabletop enclosure without needing a range tens of metres long. Used for ADAS radar and 77/79 GHz automotive radar testing.
RF Near-Field Interference Detection Box
A compact enclosure for near-field interference characterisation — identifying emission sources from electronic assemblies at close range, useful for PCB-level EMC pre-compliance.
Terminal Compact Field Testing Box
A compact anechoic enclosure for OTA testing of terminal devices, providing antenna efficiency, TRP, and TIS measurement in tabletop format rather than a full spherical system occupying a room.
How Shielded Boxes Compare to Full Chambers
| Aspect | Shielded Box | Full SAC / FAR |
|---|---|---|
| Floor space required | < 2 m² | 40–400 m² |
| Capital cost | Moderate | High to very high |
| CISPR 16-1-4 / IEC 61000-4-3 testing | No | Yes |
| Device-level OTA / desense | Ideal | Possible but over-specified |
| Production-line testing | Yes (automated formats) | No |
| Timeline to operational | Days to weeks | Months |
Combining Shielded Boxes and Full Chambers
Many mature facilities use both: a full SAC for CISPR/IEC compliance and MIL-STD-461 qualification, a reverberation chamber for DO-160 testing, plus desense and throughput boxes for daily R&D screening and production verification — keeping the full chambers free for their intended formal qualification role.
Selecting the Right Enclosure
The shielded box family is most useful for production or high-throughput R&D wireless testing, device-level receiver or antenna characterisation, radar module testing without a full range, or near-field EMC characterisation at board level. Finch supplies the full range of shielded box enclosures plus the RF instrumentation needed for a complete measurement system.