Özet:

Radio telescopes allow astronomers to observe across the entire accessible electromagnetic spectrum that extends far beyond the visual or "optical" region. Each frequency range provides its own insights and often requires its own variety of telescopes and detectors. Radio astronomers research objects which emit or absorb energy from 13 MHz to 2000 GHz and studies are carried out at every frequency where the atmosphere is transparent. 1420 MHz is one of the frequency values where radio astronomical measurements are carried out. Neutral hydrogen (HI) emissions, with a wavelength of 21 cm at about 1420 MHz, originate from distant places and directions in the galaxy, pass through interstellar clouds and occur in ground-based radio telescope observations at Doppler shifted frequencies. Maps made from HI emissions reveal the spiral structure of the Milky Way Galaxy. Measurements are carried out with the RF block of radio telescope systems. Bandpass filters are one of the most important components of this RF block. In this study, a microstrip bandpass filter was designed for 1420 MHz radio telescopes using the Stepped Impedance Resonator (SIR). In the design, parallel coupled lines are used together with the stepped impedance resonator. The filter was designed with the Keysight ADS and lengths of parallel coupled lines were optimized to achieve the desired design criteria. As a result of the simulations, the 3dB bandwidth of the designed filter was found to be 130 MHz, the insertion loss (S_{21}) was -0.152 dB, and the input reflection coefficient (S_{11}) was -38.018 dB. The designed filter has the criteria to be used in the RF receiver block of 1420 MHz radio telescopes. The filter designed in the study can be used in radio telescope systems for educational and experimental purposes

Anahtar Kelimeler: