Construction of an Interferometer for Radio Astronomy

Indianapolis, IN

When trying to uncover the properties of astronomical objects with high resolution an interferometer is the instrument of choice. This project displays the construction and use of an interferometer which resembles that of a professional, but at an affordable cost and undergraduate-level knowledge. The interferometer constructed is an adding radio telescope interferometer based on the Michelson and Pease stellar optical interferometer with the intention of measuring the diameter of the Sun. Radio signals from the Sun propagated towards two flat mirrors located on the outsides of a ladder, creating the baseline length. The signals reflect off these mirrors and traveled towards two central flat mirrors which were again reflected, but this time into a commercial satellite dish. The dish combines the signal, which is detected by a feedhorn. The receiving system following the feedhorn converts the high frequency incoming signals to a lower frequency and then amplifies it. Using a bandpass filter, the frequency range of the signal is narrowed by cutting out unwanted frequencies. The signal was then digitized using LabPro which converts the AC signal to DC, allowing high frequency signals to become an output voltage. This was modeled after a project by Jin Koda at Stony Brook University and published in the American Journal of Physics. (2016)