Question on X-band waveguide

[wcd]

All, I am trying to identify a section of waveguide. It is X-band. Looking into the waveguide from one end you can see that it tapers with what looks like steps (for lack of a better term) into a small slit about 1mm wide halfway into the waveguide. On the other side of the slit, it expands back to the full size of the x-band. There are four tuning slugs, two for each taper on each side of the slit. Does anybody have any idea what this might be? Thanks -Bill

 

[VEBill]

Where does the 'slit' go? Is it open to the air, or is it actually a closed groove?

 

[VEBill]

By the way, you could take a photo and post it as an attachment on Egineering.com (see Step 3 Attachment in the post box below).

 

[wcd]

The "slit" is open, about 1mm wide and runs the long-length of the x-band wave guide. I'm not sure what you mean by "open to the air". The slit is inside the waveguide. It's like the wave guide tapers down to the slit and then tapers back up again on the other side of the slit to full size. The slit does not block the wave guide in any way. I can blow air from one end of the wave guide to the other.

On either side of the slit, there are two tuning slugs. I just tried uploading a 4.8 Mb video but got a server error.

I'll upload the video to my web site. Try going to

http://www.electronicsrevisited.com/video.MP4

Thanks -Bill

 

[VEBill]

(Good thing I have an iPhone. LOL.)

I've not seen one exactly like that before, but I presume it's probably a filter (?). Being a two-port passive device rules out many more-complicated possibilities.

Since they're squeezing the RF through a smaller gap, if it's a filter, then probably high-pass (?).

Did I see a part number written on the side?

 

[Higgler]

I've worked with waveguide filters and I'd expect tuning screws in the center section, not in the outer edges. Doesn't seem like a filter.

It might be a dielectric test fixture whereby the thickness of the inner section is 0.031" or 0.062" tall (standard dielectric thicknesses). Measurements of S11 and S21 could be used to determine dielectric constant and loss tangent of RF circuit boards at X band.

 

[wcd]

Thanks all, I assumed it was a filter myself since it had the "waffle-iron" appearance. What you see tapering inward on the video goes to the mid-point of the waveguide (between the front two and rear two tuning slugs) and it then tapers back outward again.

There are numbers on the side but I could not find anything in a search. They are 19200-10548234 Then: MFR-52476 and on the side is stamped: 32763

This was likely from a military application. I don't think it was from a test fixture, I have a lot of them !

Thanks again

- Bill

 

[Higgler]

http://www.colemanmw.com/

waveguide filter company from your cage code.

 

[VEBill]

Sometimes radars will have a section of waveguide designed to arc over when the extremely high power transmitter is actually transmitting. The arc itself acts as an RF short circuit to reflect most of the transmit RF power away from the rest of the receiver. Of course the receiver still requires additional limiters to clean up the residual leakage.

I don't think that's what you have. But I mention it just in case it is.