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Improving Waveguide-to-Coax Transitions

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Junior Member level 2
Jul 28, 2010
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I've seen some researches on waveguide-to-coax transitions doing simulations to improve the response of the transitive by varying the design parameters/dimensions of the transition until it gets the best match possible.
Now beyond than that, does anyone know other methods on how a wg2cx transition design is further improved in the industry? Like for example how some wg2cx are customized to suit several particular frequencies or bandwidths? Any ideas?

As far as l knows, most of the waveguide to coax transitions are so designed that it covers the whole frequency range of the waveguide primary mode of propagation. Design of such transition isn’t to complex, and no special design process is needed. If there is need for really special transition to cover frequencies that are in the area of higher mode of propagation in the waveguide, then it considers special approach characterized by requirements.

Design principles of a coax to waveguide transition are offering an uncertain guide. Manufacturers utilize empirical approach to achieve a good result.
As such devices are in high market demand, they keep the design as "know-how", secret.
You can try your approach; maybe you succeed- then you can compete in the market. Or, find money and buy a good one!

Agilent transition have some steps in waveguide port to get better performance and wider bandwidth.

Agilent transition have some steps in waveguide port to get better performance and wider bandwidth.
Do you have some links/sources of these steps from Agilent? :) Share me sources if you find any. Thanks.

I agree, that HP coax to single ridge to rectangular guid design is a classic. No tuning required for the full wg band. Unfortunately, the info was contained in an HFSS design example from when HP sold HFSS. Now that they have parted ways, they apparently scoured the internet and erased all copies of it. Good luck, maybe someone has the app note squireled away.

I have a question.. How does a ridge or double ridge transition differ from a regular waveguide to coax transition? What does the ridge do to the output?

As I mentioned, all transition manufacturers have their secret "know-how' and I am sure they will not share it with you.
Try to use your head and hands and find out your solution!

---------- Post added at 16:40 ---------- Previous post was at 16:36 ----------

To "mmrobles" The ridge and double ridge does not refer to a transition but to the type of a waveguide. Ridged waveguides are used in wideband systems as their bandwidth exceeds that of standard rectangular waveguides. So there are also special transitions to coaxial line for such waveguides.

Coaxial line is the widest of all, from DC to xxx GHz depending on the connector and line diameter. But it is lossy, so we prefer using waveguides having much lower loss.

Oh... Thanks for your second input. That was helpful. I already did study a simple wgcx transition (thru simulation) for a project, and now looking forward on how to extend my research further. As I couldn't see related literatures on how these transitions are improved beyond the empirical approach, I tried to ask for some inputs here. Or at least get some ideas on how they improve it.

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