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Presenter: Nasrin Tasouji
Supervisor:

Date: Thu, July 20, 2023
Time: 15:00:00 - 16:00:00
Place: ZOOM - Please see below.

ABSTRACT

Link: https://uvic.zoom.us/j/87829400180?pwd=bDBJczVvUllQQVVtNTBYbHVwclordz09
Meeting ID: 878 2940 0180

ABSTRACT

Parabolic reflectors, typically constructed from metal or mesh materials, are utilized to gather, and concentrate incoming radio waves onto a receiver or antenna system. Reflector-based radio telescopes play a crucial role in modern astronomy by enabling the detection and analysis of radio waves emitted by celestial objects. Interferometry, a contemporary technique utilizing multiple reflector antennas, allows for precise localization of specific radio sources. This method has gained popularity due to its affordability compared to using a single, larger reflector antenna. To address the challenges of reducing the number of receivers operating across a wide frequency range in future large radio telescope arrays, octave band receivers have been introduced. These instruments require the development of front-end millimeter-wave components such as feed horns, ortho-mode transducers (OMTs), lenses, vacuum windows, low-noise amplifiers (LNAs), couplers, and more. The advancement of wideband receivers capable of covering multiple octave bands maximizes observation efficiency and reduces operational cost. Octave band antennas are specialized components employed in radio telescopes to capture radio waves across octave bands, resulting in a wider frequency coverage and increased versatility in observing a diverse range of astronomical sources. These antennas are designed to efficiently transmit and receive radio signals across a broad frequency range. OMTs are vital elements in contemporary radio and satellite communication systems, as they facilitate the separation or combination of signals with different orthogonal polarizations.

This presentation focuses on the analysis and design of a novel octave-band system, including a feed horn antenna with high aperture efficiency operating between 20 GHz and 40 GHz. To facilitate future measurements, a transition from circular quad ridged waveguide to rectangular double ridged standard waveguide is developed. In order to receive both vertical and horizontal polarizations, a novel turnstile junction based OMT is presented. The quad-ridge OMT demonstrates low loss, and insertion loss and desired cross polarization using a Y junction. Future designs will incorporate a four-port 180-degree hybrid combiner (magic-T) to ensure proper termination of certain modes instead of potential trapping.