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How do i calculate the size of a dish i need for a specif frequency, specifically around 95 mhz? Answered

How do i do so?
I plan on making a home made radio telescope, but i just want to block out non-space made noise.

Tags:radiodishsatellitestarspaceearthlisten

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steveastrouk
steveastrouk

10 years ago

AFAIK, dishes are not terribly tunable, its the LNB that does the selectivity.

Gain of a dish IS controlled by the wavelength I suppose, but not as highly tunably as a Yagi.

The gain of a Dish is proportional to D2/lambda2, so if D< lambda, it isn't a good thing.

95Mhz (3metres) is such a long wavelength, you'll struggle to get any great directionality with a dish , since, for a practical amateur dish, you're not going to have more than 2 waves or so of diameter.

For an amateur radio scope, a Yagi is a MUCH better design option.

Steve

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rickharris
rickharris

10 years ago

The dish size is related to gain and beam width and therefore resolution not frequency.

I would also go with the high gain Yagi as a start. - When did you last see a "small" radio telescope unless made up of thousands of smaller dishes.

http://en.wikipedia.org/wiki/Yagi-Uda_antenna