What are Shielding Tents?
Shielding tents are basically a Faraday cage and are used to create an isolated RF environment to conduct various RF/EMC measurements and testing. They are made from highly conductive, lightweight, and ultra-strong textiles (for example, Ni/Cu/ Aluminium/Ag plated Nylon fabric (RS)). These tents eliminate the unwanted ambient electromagnetic signals that penetrate the EMC test site; hence ensuring the elimination of interference for the Equipment Under Test (EUT). They also prevent RF leakage during EMC tests; hence ensuring the protection of human beings and also eliminating interference with electronic/electrical apparatus in the surrounding area.
Fig. 1 EMI/RFI Shielded tents/bags
The shielded tents usually have a self-standing frame or multiple ropes so they can be easily be attached to the ceiling. A single layer tent and provides typical attenuation levels of 40-60 dB and double-layer tents can provide typical attenuation levels of 70-90 dB at GHz frequency ranges. They are also available in different sizes/shapes (for example, standard pyramid, rectangular, and square) and can be customized to the required sizes/shapes. Shielded tents have advantages such as they are easy to mount and move to create a mobile laboratory. The size can also be customized.
Shielded tents are ideal for conducting EMC experiments, RF measurements, mobile military or forensic activities, pre-compliance testing, military field or embassy use, secured or TEMPEST communication, radar-jammer protection, electromagnetic allergy /electro-smog, temporary EMI shielding, reverberation chamber (RVC), mode-stirred chamber (MSC), and personal protection in the field.
How does it work?
The working of RF shielding tents is based on the Faraday cage principle. The internal/external electromagnetic field (EMI) field that strikes the shielding tents creates charge distribution in the conductive enclosure. The distributed charges align in the same direction as that of the electric field and establish a potential difference across the metal enclosure on opposite sides. Since the metal cage is closed, there will be a current flowing through the metal surface and cancel the electric field inside the RF tent and hence block the EMI.
Key Parameters of EMC Shielding Tents:
Typical RF shielding attenuation/ shielding effectiveness: Represents the maximum shielding effectiveness/attenuation (in dB) provided by the shielded tent at a given frequency range (kHz to GHz).
Outer dimension: Represents the outer dimension of the shielded tents in L (cm) × W (cm) × H (cm).
Opening dimension: Represents the opening size of the shielded tents in W (cm) × H (cm)
Shielding: Represents the shielding type. It may be the single/double layer.
Material: Type material used in the shielded tents.
Operating temperature: Represents the operating temperature range of the shielded tents in °C.