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New technologies driving decade-bandwidth radio astronomy: Quad-ridged flared horn&compound-semiconductor LNAs

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  1. Tez No: 597900
  2. Yazar: AHMED HALİD AKGİRAY
  3. Danışmanlar: DR. SANDER WEINREB
  4. Tez Türü: Doktora
  5. Konular: Fizik ve Fizik Mühendisliği, Astronomi ve Uzay Bilimleri, Physics and Physics Engineering, Astronomy and Space Sciences
  6. Anahtar Kelimeler: Belirtilmemiş.
  7. Yıl: 2013
  8. Dil: İngilizce
  9. Üniversite: Calıfornıa Instıtute Of Technology
  10. Enstitü: Yurtdışı Enstitü
  11. Ana Bilim Dalı: Belirtilmemiş.
  12. Bilim Dalı: Belirtilmemiş.
  13. Sayfa Sayısı: Belirtilmemiş.

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Özet (Çeviri)

Among the branches of astronomy, radio astronomy is unique in that it spans the largest portion of the electromagnetic spectrum, e.g., from about 10 MHz to 300 GHz. On the other hand, due to scienti c priorities as well as technological limitations, radio astronomy receivers have traditionally covered only about an octave bandwidth. This approach of \one specialized receiver for one primary science goal" is, however, not only becoming too expensive for next-generation radio telescopes comprising thousands of small antennas, but also is inadequate to answer some of the scienti c questions of today which require simultaneous coverage of very large bandwidths. This thesis presents signi cant improvements on the state of the art of two key receiver components in pursuit of decade-bandwidth radio astronomy: 1) re ector feed antennas; 2) low-noise ampli ers on compound-semiconductor technologies. The rst part of this thesis introduces the quadruple-ridged ared horn, a exible, dual linearpolarization re ector feed antenna that achieves 5:1{7:1 frequency bandwidths while maintaining near-constant beamwidth. The horn is unique in that it is the only wideband feed antenna suitable for radio astronomy that: 1) can be designed to have nominal 10 dB beamwidth between 30 and 150 degrees; 2) requires one single-ended 50 low-noise ampli er per polarization. Design, analysis, and measurements of several quad-ridged horns are presented to demonstrate its feasibility and exibility. The second part of the thesis focuses on modeling and measurements of discrete high-electron mobility transistors (HEMTs) and their applications in wideband, extremely low-noise ampli ers. The transistors and microwave monolithic integrated circuit low-noise ampli ers described herein have been fabricated on two state-of-the-art HEMT processes: 1) 35 nm indium phosphide; 2) 70 nm gallium arsenide. DC and microwave performance of transistors from both processes at room and cryogenic temperatures are included, as well as rst-reported measurements of detailed noise characterization of the sub-micron HEMTs at both temperatures. Design and measurements of two low-noise ampli ers covering 1{20 and 8{50 GHz fabricated on both processes are also provided, which show that the 1{20 GHz ampli er improves the state of the art in cryogenic noise and bandwidth, while the 8{50 GHz ampli er achieves noise performance only slightly worse than the best published results but does so with nearly a decade bandwidth.

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