Traveling Waveguide Explained: Constant vs. Gradient & Coupled Resonant Cavities

[CL39]

For traveling waveguide, if the central aperture diameter is constant from beginning to the end, it is known as "constant impedance" where the electric field is attenuated and
is diminished by the time wave reached the end of the waveguide
.
If the central aperture is tapered (larger opening in the beginning and gets narrower) it is
known as "constant gradient" where the electric field is maintained constant down the guide.

Can you explain for each mode, why that is true (why does having constant aperture means
E fields gets attenuated and why tapering helps maintain E field)

also, each cavities in the waveguide that are separated by the conducting discs are known as "coupled resonant cavities",
what does it mean by "coupled"?

Thank you.

 

[lennybogzy]

Citation?

Every piece of waveguide has associated loss. Loss causes signal "attenuation". Both of the pieces of waveguide you've described will have loss, and the signal will be attenuated - as in the signal at the end will have less power than the signal in.

As far as coupled, in your case it simply means joined. There will usually be a calibrated level of isolation between two coupled elements.