Small dishes:
> Small dishes - Solid surface
> Small dishes
- Mesh surface
>
Small dishes + focal plane arrays
Aperture arrays:
> Aperture plane Array (AA)
Other concepts which
have been considered:
> KARST
- LAR
- Cylindrical
reflectors
- Luneburg
Lens
> Luneburg Lens Array (LL)
The Luneburg Lens, another concept which has
been considered, is no longer being currently pursued. However, the associated
R&D program contributed key elements to SKA system design and technology.
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The Luneburg lens is a unique antenna that can receive radio signals from multiple directions at the same time. This allows astronomers to conduct multiple science programs in parallel and hence increase the return on their investment in the SKA's antennas.
The plastic Luneburg lens focuses radio waves like a glass lens focuses light. It is a sphere with a higher index of refraction at its centre than at its edge. This slows down radio waves traveling through the centre more than those traveling through the edges.
A flat sheet of incoming radio energy wraps itself around the curved shape of the lens, eventually forming a tight ball of focused radio energy on the other side. (see animation)
A conventional radio antenna, known as a feed, is used
to detect the concentrated radio energy at the lens' focus. These feeds
are represented by orange pyramids in the illustration above. Robotic
arms position the feeds for observation in a desired direction. An advantage
of this design is that only the relatively light weight feeds need to
be moved to re-point the telescope. The heavy lenses may remain stationary.
More about this design :
Animated
fly over
Animation
of Luneburg Lens Focussing Action
White papers: 2003
- 2002
On the web: ska
and csiro