Behaviour of EM-wave near a non-resonant antenna

[Timothy S.]

What will happen with the electromagnetic wave reaching an antenna when this antenna is not resonant on the frequency of the wave: will it reflect from antenna or pass through it?

Thank you

 

[Baluncore]

It does not have to be a non-resonant antenna, any conductor will scatter a signal.

A current will be induced in the conductive antenna material, that will, in effect, re-radiate the signal. The partial reflection will add to the incident wave, distorting the field locally.

Resonant structures can build up higher induced currents, forming interference patterns throughout the region.

 

[tech99]

May I mention that if we want a rod or near-resonant structure to act as a mirror, then it must be resonant at or a little below the require frequency. This often means it should be a little longer than the resonant length, and shorter rods tend to be transparent.