Does waveguides act as high pass filters or band pass filters?

wave guide act as a high pass filter
because it pass the em signals whose frequency is greater than the fc (cutt of freqency)

Well, my opinion is that waveguides (ie rectangular) act more like bandpass filters. If you design carefully the waveguide you can have it operating in a frequency region that supports one or more modes and not others because of the cut off frequency.

You are probably thinking of rectangular waveguides (there are many types). Above a particular frequency signals can propagate in a variety of modes and often a feed or probe is insensitive to some of the modes leaving the impression that the waveguide is a bandpass device. I am in the highpass camp. Above the cut off frequency virtually any signal will propagate. One can find modes and feeds that do not couple and disturbances in the guide can cause conversions to unexpected modes and an apparent bandpass appearance when in fact the guide remains a highpass structure.

Hi Azulykit,

I obviously talk about rectangular waveguides, I have already said that in my previous post. Although, I admit that I had in mind modes and not frequencies of a mode that can be transmitted in a waveguide. It is certain that if a mode has a frequency above the cutoff frequency it can be transmitted through the waveguide. But what happens in reality and not in theory? A waveguide oparates in a frequency region because of the attenuation of higher frequencies or modes and many other reasons....This is why I say that waveguides act more than bandpass filters than highpass ones.

i think they are wide band bandpass filters

they are bandpass filters

Every time I hold one up to the light, I can see light passing through the waveguide. But when I send DC through it, the positive and negative short out on the flange. So I guess it is a highpass filter.

I have read that a rectangular waveguide acts as a high pass filter as it will pass a dominant mode beyond certain cut-off frequency.