RF Shielding

RF shielding is required by industry for a range of purposes.

RF shielding is used for medical, research and certification purposes, to isolate and prevent external RF signals from interfering with sensitive measurements performed within the RF shield. RF shielding may also be used for security and military purposes to prevent eavesdropping of emissions from electronic equipment and preventing the transmission of RF signals from radio transmitters.

RF shielding is normally installed in the form of an RF shielded enclosure (also known as an RF Screened Room or Faraday Cage), which is basically a room lined on all internal surfaces with a metallic skin.

RF shielding can be constructed using prefabricated panels clamped together, or by overlaying the internal surfaces of a room with copper or aluminium foil. All power cabling entering the RF shielding passes through filters and air flow into the RF shielding is provided via honeycomb waveguide vents.

Modular RF shielded enclosures are fully demountable and can be relocated when required. Modular RF shielded enclosure panels are constructed from either timber panels sandwiched between zinc plated steel sheets, or from steel sheets folded into metal pans. Panels are clamped together in a specialised zinc plated steel frame, whilst pans are bolted together with gasket located in every joint.

RF Shielded Door

The RF shielded door is a key component of RF shielding and most modern RF shielding doors utilise sliding edge (sometimes called knife edge) technology, whereas earlier designs used a compression style of construction. A double row of beryllium copper contact fingers are used to obtain the required 100 dB of RF attenuation. For long term alignment reliability, heavy duty hinges with internal bearings are used to locate the RF shielded door with the frame.

RF Shielding Installation Requirements:

The site where the RF Shielded enclosure is to be installed should be relatively dust free and have a flat floor with a maximum uneven level of 1 cm in 3 m. Sufficient clear space is required nest to the installation area for placement of the enclosure materials during the construction phase. The electrical supply circuit for the RF shielded enclosure must not have safety switch or earth leakage monitoring as the RF power filters will each have some current leakage to earth.

RF Shielded Air Vents

RF Shielded Enclosures are a confined space and ventilation is an important requirement. To provide air flow into the enclosure and still maintain the shielding integrity, RF shielding air vents are required. These RF shielding air vents are constructed using a metallic honeycomb panel soldered into a metal frame. A minimum of two RF shielding air vents are required for each enclosure, with one providing the fresh air entry and the other the exhaust.

Power Filters are used to prevent signals entering an RF shielded enclosure via power cabling penetrating the RF shielded enclosure. The filter configuration can be varied to cater for client requirements including multiple circuits, multiple phases, supply frequency, Voltage, Current and attenuation performance. Signal cables will require a low current signal cable with sufficient bandwidth to allow the required signal to pass through the filter. DC power filters can also be provided to cater for high currents.

RF Shielded Enclosure Penetration Panel

In order to pass physical connections such as coaxial cables, fibre optic cables into an RF shielded enclosure a Penetration or penetration Panel is required. The penetration panel can be configured to client requirements with N type coaxial connectors, brass waveguide penetrations.

Compliance Engineering can provide and install RF shielded enclosures to meet your requirements and can also modify or relocate your existing RF shielded enclosure. A range of RF shielding components are available to upgrade your existing RF shielded enclosure including RF shielding air vents, RF signal and power filters & fibre optic media systems.

Compliance Engineering Pty Ltd
90 Indian Drive
Keysborough VIC 3173 Australia
Telephone: + 61 3 9763 3079
Facsimile: + 61 3 9763 9706
Email: info@compeng.com.au
Web: www.compeng.com.au
ABN: 56 101 639 588

Visit our main website for more details on the complete range of services offered by Compliance Engineering: www.compeng.com.au