We show with pleasure some recordings made by Mr. Giancarlo Madiai, amateur enrolled in the IRAS (Spezzino Astronomical Research Institute - http://www.astronomiadigitale.com/iras/) who we thank for his availability. Giancarlo, a very active investigator and an enthusiast of all that shines in the sky, has used a RAL10KIT as a receiver for implementing two instruments operating at different frequencies.

GThe experiments described, far from being definitive and exhaustive (they are a starting point to start an interesting observation of the sky with radio techniques, as an alternative the optical one, well established for amateur astronomers...), are interesting because illustrate some of the possible "roads" practicable by an amateur radio astronomer. Of course this is just the beginning ... the work continues ...

The first is a radio telescope operating at a frequency of 11.2 GHz, composed of a standard LNB for receiving TV-SAT in Ku-band and an parabolic reflector antenna offset of 120 centimeters in diameter. There follows a coaxial cable for TV-SAT of 75 Ω which carries the signal to RAL10KIT receiver.

 Transito del sole con il RAL10KIT


 Transito del sole con il RAL10KIT


The previous images show some transit of the Sun and the Moon recorded with this instrument.

 Ricevitore sperimentale basato su RAL10KIT


Experimental receiver based on RAL10KIT realized by Giancarlo Madiai and used for his radio astronomy experiments. On the left we see the power supply constructed by the author on a "breadboard" printed circuit for prototypes, at the top you see the USB interface for the connection of the radiometer to the station computer and a temperature sensor (fixed on the cover of the metal container of RAL10KIT) to check the thermal drift of the radiometer.


The second radio telescope operates at 1420 MHz: the external drives, arranged on the roof of the Loop-Yagi antenna (gain of about 20 dB, amplitude of receiving lobe of 16 degrees) and a commercial LNA (frequency input band 1350-1500 MHz, about 22 dB gain and 0.7 dB of noise figure), there follows a coaxial cable that carries the signal within a standard line amplifier for satellite TV (typical band input 900 -2000 MHz with a gain of about 20 dB) followed by RAL10KIT receiver.

 Antenna Yagi-Loop a 1420 MHz


Yagi-Loop Antenna at 1420 MHz (it is the almost vertical antenna directed toward the sky, composed of many "rings" aligned, supported by an aluminum shaft). At the base of the antenna, where the coaxial cable that carries the signal to the receiver exits, you can notice the low-noise pre-amplifier (LNA), which "strengthens" the RF signal before the long cable descent.


Giancarlo has also used a two-way power divider (Power Splitter 900-2600 MHz), before the RAL10KIT, so as to send the received signal also to a RTL-SDR receiver on USB stick (similar to that shown here): in this way you can simultaneously observe (and record) the radiometric signal (so the measurement of the average power in band associated with the received signal) with RAL10KIT and perform spectral analysis (with spectrograms) with SDR receiver and the supplied software.

 Prove di ricezione, con il radiotelescopio a 1420 MHz


Receiving test, with the radio telescope to 1420 MHz, of the center of the galaxy (Sagittarius A): the reception looks very disturbed, there are clear positive signal "night" drifts, consistent with the decrease of the outside temperature (excursion especially experienced by the external LNA unit), and less "noisy" due to the reduction of the "industrial" interference. The antenna is oriented to the meridian, with elevation of 28 degrees.

Of course, repeated tests will be necessary to confirm and highlight with certainty the transit of Sagittarius A, especially when the electromagnetic environment of the observation site is particularly disturbed.

 test di ricezione 2

This is a reception test, carried out with the radio telescope at 1420 MHz, with the antenna oriented in the direction of the Andromeda Galaxy (M31-NGC224), a giant spiral galaxy that is part of the Local Group. The second graph shows the evolution of the average value of the signal.

Actually this subject seems too weak to be detected, with certainty, by the instrument.

Privacy Contacts ® RadioAstroLab S.r.l.