coaxial to circular waveguide adapter

[yefj]

Hello, i want to construct a pin fed horn antenna,for this i need a coaxial to circular waveguide adapter.
from the article shown bellew we have three parameters:
guided wavelength
cutoff wavelength
free space wavelength.
I cant imagine these types of wavelength
is there some example i could use so i could see from where to take these parameters?
Thanks.

 

[FvM]

You are asking about basic waveguide properties, not specific to coax transition.
It would be probably best to look it up in a RF engineering text book. A brief explanation here: https://www.microwaves101.com/encyclopedias/waveguide-mathematics

Cut-off wavelength is a WG characteristic parameter, in TE10 mode, it's equal to doubled width of rectangular waveguide cross section. In the example, it can be used to calculate guided wavelength, and respectively the optimal distance of coupler pin to WG end wall.