HVAC Waveguide
When you have a situation that requires consistent air flow in an EMI/RFI shielded environment, it’s crucial to ensure that air continues to move easily through a panel while allowing for the attenuation of electromagnetic energy. HVAC Waveguides make this possible.
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When Do You Need an HVAC Waveguide Panel?
Hardened enclosures, often constructed for military use (ICS / ICD 705 compliance), are designed to protect or prevent electrical interference with or interception of sensitive electronic equipment. However, these enclosures, especially if they are also used by humans, often require the circulation of air for comfort and climate control for occupants and equipment. This means the enclosure will need openings for conditioned air to enter and exit the space. These openings then compromise the intended security, or EMI shielding, of the enclosure.
What is a Honeycomb Waveguide Panel?
A shielding honeycomb waveguide panel is a product that lets air flow into and out of an EMI/RFI shielded enclosure. The entering fresh air may be either cooled, heated, or at ambient temperature depending on the shielded enclosure environment and contents. For electronic equipment, the primary reason for airflow is usually to cool electronics; if a manned military shelter the reason is to circulate fresh air and to either cool or heat the air depending on the external environment.
How Does the HVAC Waveguide Provide EMI / RFI Shielding?
HVAC Waveguide panels are designed to protect against EMI and RFI signals, incoming and outgoing in order to protect against crosstalk and external monitoring of interception.
HVAC Waveguide panels have holes with honeycomb cell geometry. They allow for optimum “open space” surface area for airflow while maintaining the EMI/ RFI shielding requirement of the enclosure.
HVAC Waveguide Shielding Resources
Determine the Best Waveguide for Your HVAC Project
Considerations for your waveguide panels should include the following:
- Required shielding levels (ex: 60 dB shielding at 10 GHz)
- Magnetic field requirements
- Overall and opening dimensional measurements
- Mounting Method (ex: Mount into duct, surface mounting, Captive fasteners, etc.)
- Airflow requirements
Features of MAJR Products HVAC Waveguide for EMI Shielding
Ease of Installation
HVAC Waveguide panels are supplied with an installed EMI gasket and mounting holes ready for installation.
Painted Units
Waveguides mounted outside of the cabinet can be supplied with exposed surfaces painted to meet the Military Standard color of the mounting surface.
Shielding and Airflow
Honeycomb, with its 4:1 opening to depth ratio, provides the waveguide below cut-off effect required to attenuate EMI/RFI interference while only slightly impeding airflow.
Configurations
A broad selection provides options in meeting design objectives. Custom configurations available to meet specific shielding, airflow, and mounting requirements.
Installation of an HVAC Waveguide
Surface Mounted Installation of HVAC Waveguide
On Duct Surface Mount Installation
- Utilize the 0.5-inch-wide panel flanges and pre-installed EMI gasket to position the panel to the duct or wall aperture.
- Mount the panel with bolts or screws through the duct flange and into the wall via the through holes located on the panel frame.
- Ensure pre-installed EMI gasket makes continuous electrical contact to the flanged duct, RF foil or metal wall around the full perimeter of the panel to wall interface for optimal shielding performance.
“Between Duct” Surface Mount Installation
- Separate ductwork and flange outward 90 degrees to no less than 0.5 inches on all sides.
- Mount with pre-installed EMI gaskets between the duct flanges utilizing bolts and the panel through holes to secure.
- Ensure continuous duct to EMI gasket contact on both sides of the panel to the duct flange interface is required for optimal shielding performance.
Slide-In Mounted Installation of HVAC Waveguide
Slide-In panels are designed to fit and slide into existing ductwork without the need to mount to a flanged surface. They are secured to the ductwork using an integrated 3.0-inch-wide galvanized steel frame/collar.
Typical Slide-In Installation
- Utilize mounting screws drilled through the outside of the airduct and into the panel frame/collar once panel is in position. Screws can also be secured from the interior of the duct through the panel frame/collar and out into the ductwork if required. A 4.0 inch maximum screw spacing is recommended to secure panels in place while reducing gaps for EMI/RFI leakage.
- After securing the panel then weld or solder continuously around the perimeter of the panel frame/collar directly to the duct, ensure no gapping is visible in weld or soldered seams.
Alternate Slide-In Installation
- Utilize mounting screw and conductive foil tape if welding or soldering is not available.
- Maintain the recommended 4.0 inch maximum screw spacing to secure the panel in place.
- Once secured, place conductive foil tape over the screw heads and also over the panel to duct interface, ensuring good electrical contact with the foil tape on both the panel frame/collar and the air duct.
- A strong non-conductive sealant may be placed over and extended past edges of conductive foil tape to help hold it in place if the airduct is subject to very high vibration or temperature extremes.
Recessed Mounted Installation of HVAC Waveguide
For optimal operation of the Waveguide, make sure there is tight compression and complete electrical contact between the full perimeter of the panel gasket and the metal wall.
On Duct Recessed Mount Installation
- Utilize the standard 1.0” wide panel flanges and pre-installed EMI gasket to position the panel to the duct or wall aperture.
- Mount the panel with bolts or screws through the duct flange and into the wall via the through holes located on the panel frame.
- Ensure the pre-installed EMI gasket makes continuous electrical contact to the flanged duct, RF foil or metal wall around the full perimeter of the panel to wall interface for optimal shielding performance.
Between Duct Recessed Mount Installation
- Separate ductwork and flange outward 90 degrees to no less than 1.0 inch on all sides.
- Mount with pre-installed EMI gaskets between the duct flanges utilizing bolts and the panel through holes to secure.
- Ensure continuous duct to EMI gasket contact on both sides of the panel to the duct flange interface for optimal shielding
performance.
For More Information on HVAC Waveguide Products
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