Thank you evryone for posting answers to my question. While I do not yet grasp the reason that wave propagation through a waveguide is restricted (among other restrictions) ) by the wavelength, I believe you have guided me so that I can pick it up from here and do some research to fully...
Thanks very much Born2bwire.
OK, so to make sure I understand: you are saying that the electric and magentic vectors of the wave must fit inside the confines of the hole, so that the peak-to-peak magnitude of the electric and magnetic vectors must be equal to or less than width of the hole...
Why does the wavelength of light have to be longer (or shorter?) than a hole diameter to pass through the hole?
Also, is this phenomenon the same reason AM radio signals cannot be picked up as well FM radio signals when driving under an overpass?