Single dish setup of the DIY radio telescope
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Amateur radio astronomy
Amateur radio astronomy
As an educational tool for the participants at the astronomy olympiad (and for myself) I constructed a simple toy radio telescope / spectrograph (/ interferometer ?) using an old TV satellite parabola and received, some spare electronics and a software defined radio (SDR). I was able to take an "image of the Sun." However, the minimum angular resolution (beam width) of my telescope was larger than the solar disk itself.
Interferometric setup of the DIY radio telescope
Interferometric setup
Interferometric setup
Using the design of the Michelson stellar interferometer (Michelson, 1920). The demands on "optical" elements at 11 GHz are quite relaxed - mirrors can be made using a single sheet of aluminium foil. Pointing the interferometric rail at the right direction is not too challenging, due to the wide primary beam of the single dish telescope.
MICHELSON, Albert A.; PEASE, Francis G. Measurement of the diameter of Alpha-Orionis by the interferometer. Proceedings of the National Academy of Sciences, 1921, 7.5: 143-146.
Single dish radio drift
Single dish radio drift
@ about 11 GHz with a TV satellite dish
Interferometric drift
Interferometric drift
Waterfall plot of solar drifts
Waterfall plot of solar drifts
Using the single-dish setup
In the X/Ku band, the atmosphere is almost completely clear. It is possible to observe the Sun during cloudy days.
In the X/Ku band, the atmosphere is almost completely clear. It is possible to observe the Sun during cloudy days.
Here, a different configuration of the radio telescopes is used, with an Arduino measuring the "total flux".
Here, a different configuration of the radio telescopes is used, with an Arduino measuring the "total flux".
Drift of the Solar disk from the center of the RT beam
Drift of the Solar disk from the center of the RT beam
A radially symmetric image of the Sun - from figure on the left.
A radially symmetric image of the Sun - from figure on the left.
Actually represents the point spread function / beam of the dish at the given frequency.
Wideband scan 23 MHz - 1.7 GHz at Ondřejov observatory using RTL-SDR. FM stations, mobile communication, TV channels, short distance RF, etc are heavily polluting the radio background.
By coincidence, the FWHM of the 7.5-m radio telescope at Ondřejov and my DIY version is very similar. Compare 7.5-m @ 1 GHz with my 40-cm @ 11 GHz.
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