Shielded Windows0 pages
Fully laminated (WF Shielding) screened windows
combine the physical strength and optical clarity of
laminated glass or plastic with the shielding
effectiveness of fine wire mesh. They complement
the more cost-effective edge-laminated type (WG
Shielding), which are designed primarily for racks
and large enclosures. Cast plastic style (WC
Shielding), featuring mesh moulded into clear
plastic, complete the W Range.
Copper wire meshes, which form a highly conductive
shielding medium, are available with a conductive
anti-reflective 'blackened' finish which is
non-oxidising and which protects the mesh,
particularly where copper is used for its high degree
of shielding effectiveness. In some instances we can
supply the mesh material in its unlaminated form so
customers can fabricate their own bespoke windows
(WM Shieldng). However, we do not recommend this
to customers inexperienced in handling the fine
mesh, which is easily contaminated or damaged.
Windows with mesh typically have in excess of a
60% open area so provide good light transmission.
Attenuation is a function of conductivity, aperture
sizes and permeability in relation to field strength
and frequency. Conventional mesh materials or
surface coatings in windows do not generally
provide high attenuation at low frequency in the
magnetic field and additional measures should be
taken to supplement the screened window
performance in such applications. Electric field and
plane wave attenuation is, however, normally
excellent and this is the area of activity for most
non-military window applications. Please contact us
for technical advice.
23
WINSHIELD | Shielded Windows
W Shielding
Applications:
Our EMI screened windows use glass and polycarbonate as their base
substrate, and can be treated to improve both anti-reflective and
scratch-resistant properties. Glass panels can be etched to provide an
anti-reflective surface. Tinted 'interlayers' can be built into fully
laminated windows to improve their anti-reflective properties
particularly where, for example, non-treated stainless steel mesh is
used.
When specifying the design for a particular application, temperature
cycling, contamination and possible accidental damage should be
taken into account. Glass windows are the most abrasion resistant
but not the best for impact resistance. They are also better for
anti-contamination than plastic. Fully laminated windows have good
properties but are less cost effective than edge-laminated types,
which provide an excellent solution for most applications.
Screened windows are generally mounted within a frame or clamp
system or are bonded onto a fascia or door panel using conductive
adhesive or caulking. Stepped windows (fully laminated only) may
have a front pane protruding through a fascia, with the rear pane
bonded inside the enclosure. The way in which the screen material
inside the window is terminated depends on the type of window -
see the individual series sections for further details. Gaskets are
another important feature that is taken into consideration as shielded
windows are often used where environmental protection is essential.
Bezel mounts can be made to suit most windows. The mounts are
fabricated from aluminium, steel or other suitable metals and can be
hinged or fitted with quick-action fasteners if required.
'Plastic Jnterlayer
'Mesh Gauze
/
Plastic Interlayer
BASIC CONSTRUCTION: FULL LAMINATION - With Plastic Interlayers
Fully Laminated Windows | WF Shielding:
Fully laminated windows in glass or plastic can be produced either
as individual windows or, for smaller size, in sheet form and
machined into segments. All fully laminated windows are
available with or without a step and with or without a silver
painted busbar. Surface treatments for scratch resistance or
anti-reflectance are available and tinted inter-layers for
anti-reflectance or contrast enhancement can be supplied on
request.
Standard terminations for individually produced windows
are flying mesh, foil or silver painted busbar or conductive
gasket. Sheet-cut windows, including stepped types, are
only available with silver busbar and optional gaskets.
Care should be taken with stepped windows, particularly
glass ones, as the pressure exerted by the gasket under
compression can easily overstress even a fully
laminated window. We suggested that stepped
windows should be plastic or a composite where the
glass pane is not under pressure when mounted.
Most gaskets in our range can be used with shielded
windows and the actual type selected will depend
on the degree of shielding and environmental
protection required. Please contact us for
technical advice.
P & P Technology Ltd
1-3 Finch Drive
Springwood Industrial Estate
Braintree CM7 2SF
T:+44(0) 1376 550525
www.p-p-t.co.uk
"