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Waveguide pressure window

Waveguide pressure window

Waveguide pressure window

If you had to make a waveguide pressure window at 2.45 GHz, narrowband, 30 KW CW, 100 PSIG pressure, and 700 deg F temperature on one side, other than rolling on the floor laughing, how would you recommend getting started?  What window material, how would you bond it to the flange, what flange material(s), etc?  Thanks


Maguffin Microwave wireless design consulting

RE: Waveguide pressure window

Quartz Glass Windows are common I think.

Find Radar designers from the AOC (probably older folk).  

Some of the present shipboard systems have pressure windows and their peak power is very high. I worked on some for Raytheon.
MDL makes them "Waveguide Pressure Windows".

Search Patents, they tell everything about a design.



RE: Waveguide pressure window

I am looking for specific information, such as how to bond the glass to the flange frame to withstand high temperature and high pressure.  The commercially available ones have some limitations there.


Maguffin Microwave wireless design consulting

RE: Waveguide pressure window

I've seen (and I'm sure you have too...) lots of waveguides with O-rings to seal the high pressure gas inside. But they're up against another flat surface flange. But this concept suggests the solution...

What's on the other side of the joint?


RE: Waveguide pressure window

What I have learned is that if the flange face is below 600F, there are silicones and other types of materials you can use for the gasket (o-ring).  Above 600 deg F and it will have to be a graphite based gasket.

Some make various types of glass windows that are bonded to a kovar ring.  The kovar ring is then soldered into the flange.  But that requires the flange temperature to be considerably below 600 F, or the solder melts/weakens.  Higher temperature solders will crack the glass.

I am hoping for some newer technology, like laser welding the ring to the flange, metal to metal compression seal (like on a hermetic sma connector, only bigger in scale), or forming the glass seal directly into the flange without the use of soft solder.

To handle the pressure, we are talking about a pretty thick piece of glass or ceramic in the window.


Maguffin Microwave wireless design consulting

RE: Waveguide pressure window

How about running a cooling loop?

My thinking is basically you have 700 degrees somewhere (presumably in the sample being heated by the 2.4 GHz), but it doesn't NEED to be 700 degrees at the flange.


RE: Waveguide pressure window

That is what I am doing right now, running water to the pressure window assembly to keep the metal parts cool.  But in production, where there are multiple windows used, it will get to be a logistics problem to run water cooling to each one.  Also, I am not sure if cooling the flange, but not the glass, is such a good idea, as there will be extra thermal expansion stresses on the glass every time the unit turns on/off.  In other words, if the glass is at 600F and the flange is at 400F, that is a lot easier to take then if the flange is at 100F due to water cooling.


Maguffin Microwave wireless design consulting

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