Echo of a wave length

Hi,

In the electromagnetic wave lengths say from x-rays to the 21 cm hydrogen line, the wave has a wave length.

When it hits a receiver, eye, camera sensor whatever, it is turned into an electrical signal that can be interpreted by that device.

Now we get to my question, is there an echo of that wavelength in the final signal? Why I can hear you ask.

If there is an echo then a generic receiver could be built that covered all wave lengths at the same time.


Please help.



Thanks!



I didn't find the right solution from the Internet.



References:

forum.cosmoquest.org/showthread.php?167583-Echo-of-a-wave-length

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