Hi I have this question for sometime, and until i found a recent post here on this forum (wavelength and aperture) i thought i was the only person who just plain didn't get it. My questions arises firstly when i consider antennae and as roughly quote from the many texts i have read "to receive the maximum power radiated the antenna should have a physical size in multiples of the wavelength of the signal to be received" that is for example 1/4lambda etc I then take a look at waveguides and the general idea here besides all the math and different type of modes. The waveguide will have dimensions in width that relate to the wavelength of the signal typically microwave. It is clear also that as the frequency goes up the required physical size of the antennae or satellite dish become smaller (the obvious reason why we don't transmit signals using sound waves)? The above 2 examples are confusing conceptually because i can't get away from the idea that amplitude is more likely to have a bearing on the size of the antenna or waveguide. I can visually see the "wavelength" reaching out to the parallel walls of a waveguide and somehow affecting or being affect by the waveguide. I do have a question which relates the same problem i have with mirrors, wont go into it right now. Appreciate any suggestions on this.