Feeding in Circular waveguide ?
How to provide feeding in circular waveguide. Is it possible to provide feeding on the back side of the wall.
You have to have a magnetic or electric probe in the region of the maximum magnet or electric field you want to excite.
Hi
You can use a rectangular to circular transform,it is very useful.
Depends on what mode you want to use the circular waveguide too.
The most easy exitable mode is TE11. It's the most "robust" to unwanted modes and you may acheive a moderate BW.
TE11 may be exited by a E probe perpendicular to the sidewall (from a coax connector) or by an rectangular to circular transformer from the back wall (from a WR).
About the loss: the TE11 is a moderately low loss mode.
The lowest loss mode, TE01, is nearly impossible to exite, only few factories around the world produce launchers and only for narrow BW.
As you asked, I'll share some pictures of some Waveguide Circular feeding.
Unfortunately i cannot provide the dimensions, but as you may see the tapered version are 1 or more Lambda long, the step version has every step lamda/4 long.
For the design a Mode Matching code is the best, also HFSS may be used.
But... if you understand the concept... the pocket calculator may be enough.