Stressed dish antennas for radio astronomy
A stressed dish (or stressed-skin parabolic reflector) is a lightweight reflector design where the parabolic surface is formed by tension and stress in the materials, rather than machining a rigid paraboloid. This is particularly useful in radio astronomy and satellite ground stations, where very large apertures are needed but a solid dish would be prohibitively heavy and expensive.
Key features of a stressed dish antenna:
- Structure:
Instead of a heavy continuous surface, the reflector is made from flat panels or mesh stretched between radial ribs or cables. The ribs themselves are stressed into position, forming the paraboloid shape. - Materials:
Commonly aluminum sheets, wire mesh, or composite panels. Mesh reflectors are especially common at longer wavelengths (like 1420 MHz hydrogen line work). - Support:
The rim of the dish is a rigid ring, but the interior is lighter and relies on stress forces to maintain the parabolic curve. - Advantages:
- Much lighter than a conventional solid dish.
- Cheaper to build for large diameters.
- Easier to transport (can be assembled on site).
- Drawbacks:
- Surface accuracy is limited by how well tension is maintained.
- Thermal expansion, sagging, or uneven stress can distort the paraboloid.
- Best suited for longer wavelengths (cm–m range) rather than very high-frequency microwave work, which demands sub-mm precision.
Example use cases:
- Some radio telescopes (particularly in the 10–30 m range) use stressed-skin or stressed-mesh reflectors.
- Cassegrain and offset-fed stressed dishes are common in satellite communications.
- NASA and ESA have experimented with stressed-membrane reflectors for deployable space antennas.