Physik | Technik
Léonor Pascal Joseph Knecht, 2002 | Biberstein, AG
Damien Lagler, 2004 | Aarau, AG
Michael Zimmermann, 2001 | Staufen, AG
The goal was to build a radio telescope that would be able to measure the pulse of a pulsar. A pulsar is a fast-spinning neutron star, the corpse of a dead star. After looking at different radio telescope types, it was decided to build a paraboloid radio telescope. The construction was planned and sketched. All the needed parts were ordered, and the mainframe construction took place at home, where the different parts got cut out and attached to each other. The last part of the construction took place at a remote location because it wouldn’t be possible to transport the completed radio telescope with a diameter of 4 metres. In the end, a working radio telescope, with which it was possible to measure stellar objects like the sun or pulsars, was built. The pulsar measurements were successful and verified by an astrophysicist.
(I) Can we construct a radio telescope using low-cost materials? (II) Can we detect the pulse of a pulsar using the radio telescope?
We decided to build a paraboloid-type radio telescope, as this was the most feasible and usable radio telescope type for amateurs. After picking a suitable pulsar, we optimised the parameters of the telescope accordingly. The paraboloid was built from individual segments made of wire mesh. The segments were connected to each other using metal wires, and the paraboloid was held in place inside a trampoline frame. A dipole antenna was placed into the focal point of the paraboloid using chords. After the instrument was completed and tested by measuring the sun’s radiation, the telescope was aligned toward the pulsar’s position. Then a 45-minute measurement was taken, during which the pulsar travelled across the telescope’s field of view. Using an RTL-SDR, the signal from the radio telescope was measured and then analysed to extract the pulse of the pulsar from the background noise.
The radio telescope worked as planned; it is simple to use and easily adjustable. The collected data was represented in a diagram, which plotted the intensity of the signal against the pulsar’s spinning time. After smoothing the graph, a clear peak and a smaller side peak were visible, which is typical for a pulsar.
The telescope’s shape was sufficient for our purposes, but the shape wasn’t perfect. To increase our signal strength, we could build a larger paraboloid reflector, which also would improve the resolution, thereby further reducing noise. Furthermore, to enhance the overall radio telescope performance, a supporting structure could be added to build a more accurate paraboloid, thus allowing us to observe higher frequencies. The large peak represents the main pulse of the pulsar. The smaller peak may be an interpulse. When comparing our result to ones made from a professional radio telescope, the width and position of our peak(s) shows correlations. As the peak was comparably small, there are several factors that could falsify a pulsar’s pulse. However, we made some further measurements to reduce the risk of such events.
It’s possible to build a functional radio telescope using low-cost materials which was able to detect the pulse of a pulsar.
Würdigung durch den Experten
Die vorliegende Arbeit der Herren Knecht, Lagler und Zimmermann zeugt von grossem Mut und hoher Einsatzbereitschaft ein Radio Teleskop zu bauen mit Mitteln aus Nachbars Garten (Trampolin) und Verstärker von eBay. Ein funktionierendes Radio Teleskop hält etliche Hürden bereit aber sie haben es geschafft plausible Messergebnisse zu gewinnen, angefangen von der Radiostrahlung der Sonne und als Krönung der Nachweis des Pulsars PSR B0329+54. Sie haben sich detailliert auseinandergesetzt mit der Parabolantenne, dem rauscharmen Verstärker und nicht zuletzt der komplexen Software zur Datenerfassung.
Sonderpreis «Forschung auf dem Jungfraujoch» gestiftet vom Paul Scherrer Institut
Alte Kantonsschule Aarau
Lehrer: dipl. phys. Karl Haab