Thanks for all this info! -----Original Message----- From: Chuck McCown via Af <[email protected]> Sender: "Af" <[email protected]> Date: Mon, 22 Sep 2014 13:22:48 To: <[email protected]> Reply-To: [email protected] Subject: Re: [AFMUG] Waveguide compatibility info?
There are two types of grooves, o-ring groove for pressurization/moisture sealing and choke flange grooves to eliminate mismatch. Choke flanges are CBR, where moisture sealing are PBR and flat are UBR. You want to use a PBR with a UBR if you can. The UBR gives the O ring a good flat surface to mate with. Not sure how well two PBRs would work against each other. I would not recommend it if you wanted to pressurize. Two UBRs will be fine from an electrical point of view but could not bre pressurized. Choke flanges are more for high power applications. I don’t think I have ever seen one on lower power comm equipment. But for basic signal work, all of this stuff will work if you get them relatively close to each other. They don’t even have to be fully touching or perfectly aligned. I have taped them together in a pinch and they have run for years that way. Two screws and they are good to go for many applications. It almost seems like the signal is clingy to the inside of the waveguide like capillary action. Of course if you are trying to get rid of leakage in or out for extreme weak signal work, you would want to put in all the screws. From: Colin Stanners via Af Sent: Sunday, September 21, 2014 6:25 PM To: [email protected] Subject: Re: [AFMUG] Waveguide compatibility info? Can grooved and ungrooved waveguides be safely be used together, e.g. in outside weather? Like PBR and UBR? On Sun, Sep 21, 2014 at 12:10 PM, Chuck McCown via Af <[email protected]> wrote: Waveguide is a broadband bandpass filter. You can couple one size to another as long as there is overlap in the pass band. Go to low in frequency and the waveguide just blocks the signal. The cut off frequency. It is not a brick wall filter. Normally the cut off frequency is something like the 1 dB mismatch loss frequency, go lower and the loss goes up quickly. Different problem in going too high. To use my photon analogy: Photons simply will not fit down the tube if they are too large (low frequency). Go too high in frequency and you get other than single file photons trying to get town the tube. Like two abreast, two rows two columns etc etc. Those are called higher order modes and you can use them if you take care of launching and receiving the signal in a low loss high return loss manner. http://www.rfcafe.com/references/electrical/waveguide-chart.htm Then there are the non rectangular waveguides. Ridge waveguide is physically smaller than rectangular waveguide. Circular is good for dual pol and is exceedingly low loss but extra care has to be taken to prevent polarization rotation. -----Original Message----- From: cstanners--- via Af Sent: Saturday, September 20, 2014 6:41 PM To: Jason McKemie via Af Subject: [AFMUG] Waveguide compatibility info? Does anyone have resources/FAQs/etc to understand Waveguide compatibility?
