The radio telescope at Arecibo, Puerto Rico, has a reflecting spherical bowl of 300 m diameter. Radio signals can be received and emitted at various frequencies with appropriate antennae at the focal point of the reflecting bowl. At a frequency of 200 MHz, what is the angle between two stars that can barely be resolved?
answer in mrad
2007-10-12 06:04:01 · 3 answers · asked by romaine_style 1 in Science & Mathematics ➔ Physics
Ideally, a perfect-surface paraboloid reflector has angular resolution = wavelength/diameter or, for 200 mHz and 300 m, 5 mrad. Arecibo's reflector is a spherical cap with secondary and tertiary reflectors. The tertiary is called a focusing reflector and one supposes it brings the optics close to paraboloid. In the ref. document, half-power beamwidth (the usual definition of antenna resolution) is in the region of 3 to 4 arc minutes or 0.87 to 1.16 mrad at 1420 mHz, which is not too far from the ideal value of 0.7 mrad. I couldn't find a measured value for 200 mHz but I'd guess it's close to the ideal value of 5 mrad.
2007-10-12 06:45:02 · answer #1 · answered by kirchwey 7 · 1⤊ 0⤋
Yepp, that's what I did additionally (3.0 x 10^8) / 3 hundred = a million,000,000 Take that a million,000,000 and circumstances it by utilising a million.22 that's Lamda you will get 1220000 and you may desire to divide that variety by utilising your D, that's 305 m and you will finally end up with 4,000 you progression it 3 decimals, providing you with an answer of four mrad good luck
2016-11-08 02:56:57 · answer #2 · answered by ? 4 · 0⤊ 0⤋
Isn't it a paraboloid?
2007-10-12 06:18:59 · answer #3 · answered by Dr. R 7 · 1⤊ 0⤋