I have an experimental setup like so: Focussing the electromagnetic energy of microwaves

And if one looks closer at the lens, there are metal poles near the bottom of the lens (the extensions of the stands beyond the clamps) that are obstructing the path of the wave. Does their presence influence experimental results in any way at all? Since the transmitter is conical, the waves radiate like a cone. Also, (since this is a question related to the same experiment, I will ask this here) there is a dipole receiver. Does the axial or transverse orientation of the dipole receiver affect the readings taken?


What do you mean by "the waves radiate like a cone"? Anyhow, you will have reflections from the the metal pieces all around and that will be received to some extent and interfere with your measurements. if you don't want that happen then cover the metal with absorbing material. Check out how an "anechoic chamber" is constructed. Note that a dipole be it electric or magnetic receives (almost) nothing axially, its maximum is broadside. Wikipedia is your friend: http://en.wikipedia.org/wiki/Dipole_antenna.

  • $\begingroup$ Since the transmitter is conical, don't the waves spread? $\endgroup$ – Artemisia Feb 11 '14 at 22:16
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    $\begingroup$ The spreading of the wave has almost nothing to do "directly" with the metallic shape behind the aperture of your radiator. What matters when it comes to sidelobes that is the diffraction field radiated in the wrong directions is the field distribution in the aperture and that is controlled by the aperture size and the way it is excited from the throat. If the metal reflectors are not in the main beam by accident then they will only reflect the diffraction field. To avoid that you have to design the aperture field accordingly, antenna engineering. $\endgroup$ – hyportnex Feb 11 '14 at 23:03

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