Flat 'Dish' antenna from 1985 Radio-Electronics magazine

[Dave Doler K3DFD]

From one of the 80's-era Radio-Electronics magazines in the pile that was sitting on the table at the station today, I noticed a very interesting article about the design of a flat 'dish' antenna for UHF reception. 

The design uses the approach to RF that a flat 'Fresnel' lens does in visual light to magnify a book page for example. The article explains the concept in detail as well as providing a simple BASIC program to design your own.

Apparently this is called a zone plate antenna. There is a Wikipedia page about it that mentions a prototype for 6 GHz that was developed at Bell Labs in 1946. It consisted of a 10 ft × 10 ft vertical lattice of parallel metal strips in the form of a Fresnel lens and, this is what I found fascinating, the antenna feed is behind the lens requiring the wavefront to pass through it.

https://en.wikipedia.org/wiki/Fresnel_zone_antenna

An interesting article from 1985. See attached

Dave K3DFD

[Saied Seghatoleslami]

Lighthouses have used Fresnel Lens for almost forever.

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