A. A. Gridin

Phase shifter for antenna array of decameter range radio telescope

The decameter wavelength range is of Interest for radio astronomy at the present time. Construction of giant low-frequency radio telescopes has been planned and is being carried out in European Union (Low Frequency Array - LOFAR), USA (Long Wavelength Array - LWA) and in Ukraine (Giant Ukrainian Radio Telescope - GURT). The radio telescope GURT, which is being created in the Institute of Radio Astronomy NAS of Ukraine, will operate over frequency range from 10 to 70 MHz. The antenna system of telescope will be a phased antenna array consisting of many subarrays, each of 5×5 elements. The array element is a short active dipole that allows receiving of electromagnetic waves of 2 orthogonal polarizations. Phasing inside one section is performed with analog phase shifter. Output signals of the subarrays are transformed into digital form and are processed in DSP-receiver. In this work the analog phase shifter of the GURT radio telescope antenna system section, which is based on the time-delay principle, is considered. The design, electric circuit and results of experimental and theoretical researches are given and described.

Signal delivery system in a subarray of Giant Ukrainian Radio Telescope

Radio astronomy deals with the weakest signals received by a radio electronic device, and, as a result, it is very complicated problem to maintain appropriate SNR while transferring signal from the antenna output to receivers input. In this paper, a system for delivering the radio astronomical signals from dipole terminals to ADC input of Giant Ukrainian Radio Telescope (GURT) is described. Examples of the received signal spectra in wide frequency range are shown.

Diamond dipole active antenna

Advantages of the diamond dipole antenna as an active antenna are presented. Such an antenna is like an inverted bow-tie antenna, but the former has some advantages over the ordinary bow-tie antenna. It is shown that the diamond dipole antenna may be an effective element of a new antenna array for low-frequency radio astronomy as well as a communication antenna.