Preamplifiers and band-pass filters

With a 10 m large diameter the parabolic antenna reflector gives a theoretical gain of 40 dB on 1,4 GHz band. The parabola focus is located 5 metre distant from the source cavity handled by the mast boom and holding a dipole that is the receiving part of the antenna. Signals captured by the dipole are conducted to an SDR receiver via a coaxial cable. Despite this cable is a low loss one, a certain level of signals is lost and some noise added due to the length of the cable. The best strategy is thus to amplify the signal by inserting a preamplifier as close as possible to the receiving dipole.

IMG_1893

Temporarily two amplifiers have been installed at a few metres from the source. The first is a KU LNA 133BH. Its characteristics are displayed on next figure.

IMG_1896

Intrinsic preamplifier noise factor, important for overall radiotelescope receiving performances is displayed on the left scale. Gain is given on the right scale.

Gain&Facteur_Bruit

Deuxième_preampli

filtre-passe-bande

Second preamplifier is behind the first one just after a 1350-1450 MHz band pass filter.

image002

It is providing a significant improvement in receiving performances, on dongle SDR key receiving performance at 1240 MHz.

Preamplifier will be soon replaced by an even better one dedicated to radioastronomy.

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1420 MHz. LNA CAVITY BAND PASS FILTER

SKU: RAS-1420LNA-CBPF
 
1420 MHz. HP LNA with CAVITY BAND PASS FILTER.
Specifications: The filter section, will give the observer better selectivity (High Q) and will ward off some types of annoying interference, such as radar. The filter will pass the 1420 MHz signal and effectively attenuate unwanted signals. The LNA, N/F of 0.29 +/- 0.15 dB, gain of 35 dB +/- 3 dB. with N male connector.
IMG_2951
A four directions coaxial splitter has been added in order to connect the second SDR (LimeSDR) to the antenna.
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