Waveguide lens antenna

[fooladi 1]

I'm looking for  any modelling and design info about Waveguide lens antenna. Is it possible to build it as diy project?

[clanon 258]

Metallic Lens Antenna Bell Labs 1946

 

 

[clanon 258]

The lens antenna is an array consisting of 680 rectangular waveguides arranged rotationally symmetrically around the antenna axis. The antenna operates as a concave lens, with an index of refraction n<1, which focuses the satellite signals and a reverse image of the Clark belt is projected at a focal plane behind the antenna. The concave properties of the lens ensures that the received plane waves are focused at one point.

The phase of the waves is shifted forward in the waveguide, and the properties of the waveguides determine the shift. (Dielectric) There are two Fresnel zones in the antenna and, for each zone, the signal path to the focus is one wavelength longer than the previous one. The result is that all signals transmitted through the antenna reaches the focal point in phase. The circular symmetry of the antenna eases the control of the electromagnetic behaviour and reduces cross polarization.

The media inside the waveguides is dielectric technical EPS with the effective permittivity S=1,1.(Expanded PolyStyrene) The dielectric makes the extremely thin copper waveguide walls possible with good mechanical robustness and it also allows a more compact construction as compared to air-filled waveguides.

Satellite signals in a span of 36° can be received, which theoretically allows reception from 18 satellites because the required spacing between consecutive satellites is 2°. The receivers (LNBs) are placed on a focal line behind the antenna. Offset angle reception is of course very important in multi-satellite communication and a graph of the amplitude for different offset angles, at 12.25 GHz for the North American model, is shown in the figure below. The very low side-lobe levels help reduce disturbance from neighbouring satellite reception.

 

[clanon 258]

2 hours ago, Admin said:

,,,can't open file ...!!!    I'll delete it...!!!

VERY INTERESTING info

[devton 27]

useless because:

https://encrypted-tbn0.gstatic.com/images?q=tbn%3AANd9GcQbN4PrLX2HeFXsEbDTY0c9193ykPSbLNTkVg&usqp=CAU