Monopulzni vir za globoko enozrcalno anteno

MIKLAVČIČ, PETER (author), Batagelj, Boštjan (mentor)

V doktorski disertaciji obravnavam, razvijam in optimiziram enopasoven in dvopasoven monopulzen vir za primarno gorišče globoke simetrične enozrcalne antene. Viri so primarno namenjeni uporabi v satelitskih komunikacijah, natančneje v zemeljskih postajah, ki potrebujejo hitro odzivno in visoko natančno namerjanje satelitov. Enofrekvenčni vir je namenjen desnosučno krožno polarizirani oddaji v pasu okoli 2 GHz, dvofrekvenčni pa poleg prvega še v pasu okoli 8 GHz. Večrodovni viri so sestavljeni iz okrogle votline, krpičastega sevalnega elementa za osnovni namen komunikacije in monopola za kanal razlike monopulznega namerjanja. Po uvodu v delo sem najprej napisal pregled tehnik sledenja oziroma namerjanja izvora v prostoru s poudarkom na monopulzni tehniki. V nadaljevanju sem predstavil problematiko osvetlitve globokega (simetričnega) paraboloidnega zrcala z virom v primarnem gorišču. Pri analizi osvetlitve so predstavljene tudi posamezne izgube (izkoristki) pri končni učinkovitosti osvetlitve zrcala in celotni učinkovitosti zrcala ter izračun ocene razmerja dobitka antene proti šumni temperaturi G/T v tipičnem radijskem okolju satelitskih komunikacij. Poudarek pri obravnavi je na večrodovnih monopulznih antenah ter sprejemu satelitskega signala. V praktičnem delu naloge sem zasnoval in izdelal več izvedb enopasovnih in dvopasovnih virov. Opisal sem postopke načrtovanja, optimizacije in izdelave prototipov. Ideje različnih dodatnih elementov glede na najbolj osnovno obliko sem najprej preveril in optimiziral s tridimenzijskimi rigoroznimi elektromagnetnimi simulacijami. Uporabne izvedbe optimiziranih virov sem predstavil v disertaciji in simuliral na majhnem zrcalu velikosti 10 valovnih dolžin. Optimizacija je podvržena izbranim vhodnim podatkom zrcala in cilja najvišje razmerje G/T pri ciljnem razmerju goriščne razdalje proti premeru zrcala f/d. V nadaljevanju sem izdelal in ovrednotil prototipe zasnovanih izvedb virov. Med rezultate sem zapisal simulirane in/ali izmerjene vrednosti parametrov sipanja, smernosti, dobitkov in smernih diagramov ter izračune ali ocene slabljenj, izkoristkov, šumnih temperatur ter razmerij dobitka proti šumni temperaturi. Končna primerjava izvedb virov sledi v sklepnem delu naloge.

• Language: Slovenian
• Keywords: dvopasovna antena, globoka enozrcalna satelitska antena, monopulzni večrodovni antenski vir, osvetlitev simetričnega paraboličnega zrcala, razmerje dobitka antene proti šumni temperaturi, razmerje G/T, tehnike namerjanja anten, večpasovna antena, vir za primarno gorišče antene, zemeljska postaja
• Work type: Doctoral dissertation
• Organization: FE - Faculty of Electrical Engineering
• Year: 2024
• PID: 20.500.12556/RUL-166124
• Publication date in RUL: 20.12.2024

Secondary language

• Language: English
• Title: Monopulse feed for deep single-mirror antenna

Abstract

The thesis addresses research, development, and optimisation of singleband and dualband monopulse feeds suitable as prime-focus illuminations for deep symmetric parabolic single-mirror antennas. The feeds are primarily meant for satellite communications, specifically in ground stations that benefit from fast and highly-accurate antenna pointing. Singleband design is applied to a right-hand circularly polarised transmission in the 2GHz band while the dualband design adds the 8GHz band. Multimode feeds consist of a circular cavity, an elliptic patch as a radiating element for the communication channel and a monopole for monopulse tracking referenced to the communication channel. A thesis introduction is followed by an overview of antenna spatial tracking and pointing techniques, focusing on monopulse tracking. Furthermore, problems when illuminating a deep (symmetric) parabolic mirror with a prime-focus feed are presented. Illumination analysis contains separate losses (efficiencies) forming the final illumination efficiency and total mirror antenna efficiency, as well as an estimation of antenna gain-to-noise-temperature ratio G/T in a typical satellite communication environment. The analysis is focused on multimode monopulse antennas and satellite signal reception. In the experimental domain, multiple types of singleband and dualband feeds are developed and made. Design, optimisation and prototype-production procedures are described. Different basic design modifications are tested and optimised with a three-dimensional full-wave electromagnetic simulation. Useful designs of optimised feeds are presented in the dissertation and additionally simulated illuminating a small mirror 10 wavelengths in size. Optimisations are bound to mirror properties and aim for the highest G/T ratio at the desired focal-distance-to-diameter ratio f/d. After the design phase, prototypes of designed feeds are produced and measured. Results include simulated and/or measured values of scattering parameters, directivities, gains, and radiation patterns, as well as attenuation, efficiency, noise temperature and antenna gain-to-noise-temperature estimations. A final comparison of the presented designs follows in the conclusion.

• Keywords: antenna gain-to-noise-temperature, antenna pointing techniques, dualband antenna, ground station, G/T ratio, monopulse multimode antenna feed, multiband antenna, prime-focus antenna feed, deep single-mirror satellite antenna, symmetric parabolic reflector illumination