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MODX Revolution

EMI Shielded Vents | Attenuated Vent Panels

General Information

Our lightweight aluminium honeycomb attenuated ventilation panels are available with a choice of 13 standard aluminium frame extrusions. These EMI shielded vents are designed for use in racks and other forms of commercial enclosure.


Lightweight aluminium honeycomb vents can be mounted onto most forms of emi shielded enclosure where airflow is needed, either over cooling fans or by convection. They can be mounted anywhere on the enclosure and can be fitted with protective 'kickplates' to protect the honeycomb material from accidental damage.

Where they may be exposed to the elements the aluminium honeycomb vents can be fitted with 'slant' honeycomb which provides a downward facing aperture, preventing the ingress of rainwater. This has the added benefits of directional airflow and increased attenuation due to the higher aspect-ratio of the cell structure.

Honeycomb ventilation panels are usually supplied with gaskets in a ready-to-mount form which either fits around the aperture in the equipment (non-flanged style) or is inset into the enclosure (flanged style). Depending on the performance requirements for the application, they can be mounted by bolting through clearance holes in the frame, through the use of captive threaded inserts.

Aluminium honeycomb material is formed by expanding a bonded aluminium foil into a honeycomb structure. This process, which is common to all honeycomb manufacturers, produces a material which is 'polarised' and is conductive either horizontally or vertically. To overcome polarisation problems two layers of honeycomb, mounted at 90 degrees to each other, are used. Please contact us for futher information about polarisation.

Each cell in an attenuation vent acts as a waveguide and its performance is a function of its width/height and the ratio between the depth and width of the cell. Generally an aspect ration of 4 or 5:1 is used.

Aluminium honeycomb vents are finished to suit specific applications and can be protected by Alocrom 1000, 1200, Iridite or electroplating.

EMI Shielded Vents | Attenuated Vent Panels


For gasket material specifications please refer to the knitted mesh gaskets, conductively loaded silicone and oriented wires in silicone pages.


FrequencyFieldType AF1Type AF2Type AF5Type AF9Types AF12 & AF13
10 KHz H 45 - 40 33 51
100 KHZ H 49 *77 43 37 57
1 MHz H 51 - 47 39 >105
1 MHz E >100 - 84 43 >105
10 MHz E >100 - 97 84 >105
100 MHz E >100 56 >100 79 >105
1 GHz P 98 **96 85 50 >105
10 GHz P 95 80 85 60 ***90

Figures for AF1 - 2 layers 6.3mm thick honeycomb 3.2mm cell size at 90° (cross pole) with Alochrom 1200 finish

Figures for AF2 - single layer 12.7mm thick honeycomb 3.2mm cell size with Alochrom 1200 finish

Figures for AF5 - 2 layers 3.2mm thick honeycomb 3.2mm cell size at 90° (cross pole) with Alochrom 1200 finish

Figures for AF9 - single layer 6.4mm thick honeycomb 3.2mm cell size with Alochrom 1200 finish

Figures for AF12 & AF13 - 2 layers 12.7mm thick honeycomb 3.2mm cell size at 90° (cross pole) with Alochrom 1200 finish

Tests to MIL STD 285 (modified)  

*figures for 200KHz     ** figures for 2GHz      ***figures for 10GHz-18GHz


Overall dimensions +/- 0.8mm
Fixing holes/fasteners +/- 0.5mm
  with jigs +/- 0.2mm

How to order

Specify: Shielding Series-Frame Style-Vent Media-Overall Size-Number 0f Fixings-Fixing Type/Size
Where possible please provide a detailed drawing.

Shielding SeriesFrame StyleVent MediaOverall SizeFixings (No.)Fixing Type
VH-Vent AF1 01=Cross-pole xxxx-xxxx xx C/T=Captive insert
Aluminium AF2 02=single layer     T/H=Through hole
  AF3 03=slant 45°      
  AF4 04=slant cross pole      



Examples / Notes

VH-AF1-01-2260-4330-12-T/H (4.8) specifies an aluminium cross-polarised vent panel in AF1 frame style with 12 through holes of 4.8 mm diameter. Hole positions to be agreed with the customer prior to manufacture or as shown on the customer drawing.

For aluminium vent panel types and styles not shown please contact us or forward a detailed drawing for quotation.


Demountable dustfilters are available for use with attenuation vents and are featured in the Vent / Filer Composite section. They are generally produced using the AF1, AF2 or AF5 frame styles and can be mounted with quick-release fasteners for ease of cleaning or replacement.

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