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Design of quadruple-ridged orthomode transducers with reduced modal content.
Thesis (PhD)--Stellenbosch University, 2024.
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| Format: | Thesis |
| Language: | en_ZA en_ZA |
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Stellenbosch : Stellenbosch University
2024
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| _version_ | 1867613736397701120 |
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| access_status_str | Open Access |
| author | Kotze, Jacobus |
| author2 | Meyer, Petrie |
| author_browse | Kotze, Jacobus Meyer, Petrie |
| author_facet | Meyer, Petrie Kotze, Jacobus |
| author_sort | Kotze, Jacobus |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Thesis (PhD)--Stellenbosch University, 2024. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/130316 |
| institution | Stellenbosch University (South Africa) |
| language | en_ZA en_ZA |
| last_indexed | 2026-06-10T12:40:53.123Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2024 |
| publishDateRange | 2024 |
| publishDateSort | 2024 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/130316 Design of quadruple-ridged orthomode transducers with reduced modal content. Kotze, Jacobus Meyer, Petrie Stellenbosch University. Faculty of Engineering. Dept. of Electrical and Electronic Engineering. Design of Quadruple-Ridged Orthomode Transducers with Reduced Modal Content Transducers Radio astronomy Radio telescopes UCTD Thesis (PhD)--Stellenbosch University, 2024. ENGLISH ABSTRACT: This dissertation presents new methods for the design of quadruple-ridged orthomode transducers (OMTs) that maximise coupling to the fundamental TE11 mode over large bandwidths by reducing coupling to higher order modes, as well as a measurement technique to verify the reduced higher order modal content. The use of such a quad-ridged OMT leads to intrinsic performance improvements over existing quad-ridged OMTs and allows the separate design of a quad-ridged reflector feed horn based on the OMT. Due to the separability of the quad-ridged horn and OMT, the optimisation of the horn is substantially accelerated through the introduction of symmetry planes in the full-wave simulation of the horn, and enables a much more comprehensive exploration of the parameter space describing the horn. An in-depth study of generalised quad-ridged waveguides derives useful properties such as the modal cut-off frequencies, impedance and attenuation characteristics of quad-ridged waveguides, which are not available elsewhere in the literature. Perturbations of the quadridged waveguide cross-section lead to the development of quad-ridged waveguides with increased single-mode bandwidths compared to conventional designs. A new transition to quad-ridged waveguide is presented which simultaneously addresses many of the drawbacks encountered in existing transitions, along with methods for further modal suppression to extend the bandwidth of quad-ridged OMTs. Based on the findings of this dissertation, a prototype quad-ridged OMT is designed and manufactured for the future SKA Band A. A method of extracting the full multi-modal coupling matrix for general waveguide transitions is introduced in this dissertation, and is used to successfully characterise the multi-modal properties of a manufactured quad-ridged OMT for the first time. The prototype quad-ridged OMT is measured to have no significant coupling to higher order modes, and is well-matched over the SKA Band A. The measured results verify the wideband, reduced higher order modal content design of the prototype. AFRIKAANSE OPSOMMING: Hierdie proefskrif stel nuwe metodes bekend vir die ontwerp van viervoud gerifte ortagonale modus omsetters (OMTs) wat slegs koppel na die fundamentele TE11 modus oor wye bandwydtes, tesame met ’n meettegniek om die verminderde ho¨er orde modale inhoud te bevestig. Die gebruik van so ’n OMT lei na intrinsieke verbeteringe in die verrigting van viervoud gerifte OMTs teenoor bestaande ontwerpe, en laat ook die afsonderlike ontwerp toe van ’n viervoud gerifte horing antenna voer wat gebaseer is op die OMT. As gevolg van die afsonderlike ontwerp van die horing en OMT, is die optimering van die horn aansienlik versnel weens die simmetrie in die horing struktuur. Gevolglik kan die paramater ruimte wat die horing beskryf meer deeglik ondersoek word. ’n In-diepte studie van algemene viervoud gerifte golfleiers bepaal nuttige eienskappe soos die afknip frekewensies, impedansie en attenuasie einskappe van viervoud gerifte golfleiers wat nie elders beskibaar is in die literatuur nie. Perturbasies van die viervoud gerifte golfleiers deursnit lei tot die ontwikkeling van viervoud gerifte golfleiers met groter enkel-modus bandwydtes in vergelyking met konvensionele ontwerpe. ’n Nuwe oorgang na viervoud gerifte golfleiers word ten toon gestel in die proefskif wat baie nadele van bestaande ontwerpe aanspreek, tesame met metodes vir verdere onderdrukking van ho¨er orde modusse om die bandwydte van viervoud gerifte OMTs te verbreed. Gebaseer op die bevindinge van hierdie proefskrif is ’n prototipe viervoud gerifte OMT ontwerp en vervaardig vir die toekomstige SKA Band A. ’n Metode vir die onttrekking van die volledige multi-modale koppeling matriks is bekend gestel in hierdie proefskrif, en is gebruik om die multi-modale eienskappe van ’n vervaardigde viervoud gerifte OMT suksesvol te onttrek vir die eerste keer. Die prototipe viervoud gerifte OMT het geen gemete koppeling na ho¨er orde modusse, en is goed aangepas oor die SKA Band A. Die meting resultate bevestig die wyeband, verminderde ho¨er orde modale inhoud ontwerp van die prototipe. Doctorate 2024-02-29T07:20:34Z 2024-04-26T13:10:27Z 2024-02-29T07:20:34Z 2024-04-26T13:10:27Z 2024-03 Thesis https://scholar.sun.ac.za/handle/10019.1/130316 en_ZA en_ZA Stellenbosch University xiv, 92 pages : illustrations. application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Design of Quadruple-Ridged Orthomode Transducers with Reduced Modal Content Transducers Radio astronomy Radio telescopes UCTD Kotze, Jacobus Design of quadruple-ridged orthomode transducers with reduced modal content. |
| title | Design of quadruple-ridged orthomode transducers with reduced modal content. |
| title_full | Design of quadruple-ridged orthomode transducers with reduced modal content. |
| title_fullStr | Design of quadruple-ridged orthomode transducers with reduced modal content. |
| title_full_unstemmed | Design of quadruple-ridged orthomode transducers with reduced modal content. |
| title_short | Design of quadruple-ridged orthomode transducers with reduced modal content. |
| title_sort | design of quadruple ridged orthomode transducers with reduced modal content |
| topic | Design of Quadruple-Ridged Orthomode Transducers with Reduced Modal Content Transducers Radio astronomy Radio telescopes UCTD |
| url | https://scholar.sun.ac.za/handle/10019.1/130316 |
| work_keys_str_mv | AT kotzejacobus designofquadrupleridgedorthomodetransducerswithreducedmodalcontent |