View the EMI/RFI Shielded Waveguide Air Vents product features below
Typical Mounting Methods
Since the vent-to-shield seal is normally the limiting factor in shielding performance, the following waveguide-to-shield seals are recommended.
Soldering and Brazing
Whenever possible, enclosure walls should be fabricated in a horizontal position to allow soldering or brazing in a lightweight (26 gauge copper or galvanized steel) frame to the shield wall. This produces excellent RF seals that provide reliable performance for long periods of time.
If the shielding material in the walls and ceilings is heavy enough to weld, vents with an angle iron frame should be specified. Since the waveguides are soldered into the frames using 60/40 solder, care should be taken to keep the honeycomb-to-frame joint under 150o Celsius. The preferred installation method is to use a skip welding technique around the frame until the weld line is completely closed.
Where soldering and welding are not practical, RF gasket seals can be used. Monel or tin coated gaskets provide the best RF seal. The mounting surface can be tin-lead plated or plasma spray tinned. A light cleaning of contact surfaces before assembly will insure maximum seal performance by removing unwanted metal oxides before the seal is formed.
Contact surfaces of mating surfaces should be rigid enough to carry pressure along the gasket for maximum shielding performance. Maximum enclosure-to-vent shield performance can be achieved by observing the precautions of compatible metals and by spacing the fasteners at no more than 10.16 cm (4 in) on center.
Whenever metal ducts are connected to the waveguide air vents on a shielded wall, a dielectric spacing collar is needed to create a non-conducting break on the duct. The purpose of this break is to keep RF currents on the surface of metal ducts from transferring to the shield wall and lowering shielding effectiveness. The dielectric break may take the form of a rubber or canvas boot, a wooden spacing collar, or other dielectric medium.
Minimum Resistance to Air Flow
The honeycomb (or hex-tube) design combines the highest shielding performance with the lowest resistance to air flow. Cell geometry allows the maximum amount of open space while uniformity and depth of the honeycomb tubes reduces air turbulence.