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I was wondering if receivers just catch the radio waves that pass through, or if they actually attract the waves like a magnet. In other words, will a radio wave moving in a straight line bend in order to reach a receiver if it is close enough?

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A radio wave may "bend" due to diffraction or scattering off objects, but it will not "bend" just because a receiving antenna exists.

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  • $\begingroup$ But a receiving antenna is a scattering object... $\endgroup$ – Floris Jan 28 '16 at 18:40
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When a receiving antenna picks up a signal, a current flows. This current acts as a secondary "transmission", and this will partially cancel out the electromagnetic field that is incident - this is how you get power from the EM field into the antenna. If you look "slightly downstream" from the antenna, you will see a reduction in the EM field (assuming for a moment that a plane wave was incident). And this dip in the field isn't exactly in the shape of the antenna (in the case of a simple dipole antenna, you would expect the dip to be in the exact shape of the antenna, but that is not the case - it covers a larger area).

If you just looked at the field downstream from the antenna, you would conclude that the waves must have been "sucked into" the antenna. With the induced currents doing the sucking.

So yes - there is some apparent bending going on. The higher the Q of the antenna, the greater the bending.

I found a diagram that illustrates some of this:

enter image description here

Which is part of an article that attempts to do some analysis on resonant power transfer. You may not agree with everything in the analysis, but some of the basics are sound, and in line with what I said above.

A better reference - this is the pattern of radiation seen in the vicinity of a (receiving) Yagi antenna. Again, you can see that the waves are "bending towards" the antenna, and that you therefore harvest energy from a larger area.

enter image description here

This could be considered "diffraction" of the beams, because as the first element causes a disturbance in the field, it affects propagation of the further-out waves. But it works - antennas like this have directional properties, and this is precisely because, when pointed in the right direction, they "suck power" from the incident wave over a large area.

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  • $\begingroup$ So in the case of smartphones using earphone wires as antenna, assuming the wires are bent and not coiled around itself, the "sucking" effect would be very small as there isn't much forward distance for the wave to diffract, is that correct? $\endgroup$ – busukxuan Jan 29 '16 at 15:50

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