Pressurisation Components 
(Kapton, Duroid, Quartz & Boron Nitride)

Pressure Windows

Gas Inlet Sections

Dessicant Canisters

 

 

In general three types of pressure window are available:
Glass reinforced PTFE windows and are suitable for pressures up to 40 psi. Windows for standard rectangular waveguide sizes have a VSWR better than 1.10:1 over the full waveguide bandwidth, or 1.05:1 over a 50% bandwidth. Double Ridge sizes have a VSWR better than 1.10:1 over an octave bandwidth, or 1.15:1 over the full frequency band

Kapton windows are available for lower pressures (7 p.s.i.) and offer improved performance, typically better than 1.05:1 over the full waveguide bandwidth.

Quartz windows are available for very high power or high pressure differential requirements (They are usually tailored to a customer’s particular requirements so please contact the factory for details).

Other specialised materials like Boron Nitride etc. are available upon request.

General
All pressure windows have a larger matching iris on one side - from which the window material is inserted. Although all windows can be used either way round, superior pressure handling will be achieved if this matching iris is installed on the high pressure side

Pressure windows should not be used with additional shims or gaskets as these can protrude into the matching iris and de-tune the window

Standard windows have plain faces without a sealing groove and can be supplied to mate with most common flange outlines.

Standard Rectangular

Kapton pressure windows

Specification:
The V.S.W.R. for all kapton windows between WG10 and WG22 is 1.065 : 1 (30dB)
Pressure:7 p.s.i.
The thickness of the window is similar to the waveguide flange style chosen

PTFE Pressure Windows

Specification:
Pressure : 40 p.s.i. max
The thickness of the window is similar to the waveguide flange style chosen.
V.S.W.R. - see table

 

Quartz pressure windows

Specification:
Quartz windows are available for very high power or high pressure differential requirements (They are usually tailored to a customer’s particular requirements so please contact the factory for details).

The V.S.W.R. is typically 1.1 : 1 (26dB) over approximately 1/3 of a waveguide band - but this does depend on the thickness of the quartz, which is dictated by the pressure differential.

Double Ridge

Specification:
Material : glass reinforced PTFE
Pressure : 40 p.s.i. max
The thickness of the window is similar to the waveguide flange style chosen.
V.S.W.R. - see table

 

RW

Product code
RW = pressure windowt

16

Waveguide size
British WG size for rectangular waveguide or MIL spec. WRD size for double ridge waveguide
e.g. 16 = WG16; 750 = WRD750
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S

Type
S = glass reinforced PTFE
K =kapton
Q = quartz

Z

Paint
Z = unpainted (standard)
Q = TWS blue (preferred)
B = black
G = grey

Z

Finish
Z = unplated (standard for brass)
M = passivate (option for brass)
F = Iridite (preferred for aluminium)
H = chromate
A = tin
B = silver
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402

Flange type
Last 3 digits from the TWS flange part no.
e.g. 402 = UBR flange

B

Material
A = aluminium (standard for double ridge)
B = brass (standard for rectangular)

Gas inlet sections

These are typically short sections of flanged waveguide with a pipe connection for the gas. A valve can be fitted to the pipe if required.

For minimum effect on the waveguide run, the pipe connection should be through a small hole in the centre of the broad wall. However, the pipe can be through a larger hole on the narrow wall (although this may require some tuning of the waveguide).

Inlet sections can be integrated into other components e.g. bends or pressure windows

Dessicant canisters

These components are intended for low volume atmospheric breathing systems. The canister is connected to the waveguide via an inlet section and is open to the atmosphere at the other end - so ensuring that the air entering the waveguide is dry when the system breathes.

The dessicant changes colour when it requires changing