With the help of the microwave generator, described in the post Gunnplexer & Microwaves, one can easily do some “optical” experiments to describe the behavior of these 3cm electromagnetic waves.
Microwaves Beam Reflection
With the transceiver and the receiver based on Gunnplexer is easy to check that also the band of radio frequencies obey to the laws of geometrical optics, in particular the reflection on a metallic flat surface. It can be verified experimentally that the angle of incidence with respect to the normal is equal to the angle of reflection.
Even in the case of microwaves, the phenomenon of refraction occurs when the electromagnetic wave passes through a dielectric medium. In particular the total internal reflection by the dielectric-air interface surface. As a dielectric material, we can use normal paraffin (wax) with which we have modeled two rectangular prisms.
The images below show total reflection in the first case and the transmission with no reflection in the second case when a second prism is put in close contact to the first prism so as to eliminate the air – dielectric gap interface that forms the reflective surface.
Microwaves Beam Absorption
A metal plate interposed between Transceiver and Receiver fencing completely the microwave beam and the Receiver signal is null. A slab of non-metallic and light material such as the foam does not absorb RF radiation and affects only minimally the signal on the Receiver.
Microwaves Beam Diffraction
With the Transceiver and Receiver one can check wave phenomena such as diffraction from a single slit, or the interference of the beam that passes through two close slits. Since the wavelength of the microwaves is about 3cm, the distances are of the order of tens of centimeters. If transceiver and receiver are maintained at close range we are in the case of near-field or “Fresnel”, but if the distance is much greater than the wavelength the far field approximation or “Fraunhofer” must be used, in this case it is necessary to mount on the two gunnplexers the horn antennas to increase gain and decrease the beam attenuation.
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