{"id":{"repo_id":"stellenbosch","oai_identifier":"oai:scholar.sun.ac.za:10019.1/135783"},"canonical_url":"https://search.dev.ndltd.org/etd/stellenbosch/oai:scholar.sun.ac.za:10019.1/135783","repository":{"repo_id":"stellenbosch","name":"Stellenbosch University","base_url":"https://scholar.sun.ac.za/server/oai/request"},"display":{"title":"A Tri-Ridged Flared Horn for Radio Astronomy Applications","abstract":"The research in this dissertation covers the modal analysis of three-fold symmetric structures, specifically the Tri-Ridged Wavguide (TRWG). The modal properties of these structures show high single-mode bandwidth, which presents an opportunity to check for viability in radio astronomy applications. To en-able such a study, an algorithm was developed to track and identify the modes in TRWG by using CST - a commercial three-dimensional electromagnetic analysis package. With the results of this algorithm, a modal analysis is presented for TRWGs. On this basis, a TRWG Orthomode Transducer (OMT) is designed to be cascaded with a Tri-Ridged Flared Horn (TRFH) to show that the fundamental mode will propagate with a high single-mode bandwidth. A goal function based on an S-parameter analysis for the reflection coefficient optimisation is also found. The TRWG OMT features a reference port that can be used for gain calibrations. The best result for this TRWG OMT is a maximum of −10 dB reflection coefficient across a 1.2 − 3.5 GHz bandwidth. The mode tracking algorithm is also used for a modal analysis of the TRFH. The TRFH is designed and optimised for maximum receiving sensitivity, by using existing methods and techniques used for other antennas in radio astronomy. The optimised TRFH showed a reflection coefficient of −20 dB when a perfect OMT is used in CST. When including the OMT, the maximum receiving sensitivity of 15 m2/K achieved on the shaped ngVLA reflector remains unchanged.","abstract_html":"The research in this dissertation covers the modal analysis of three-fold symmetric structures, specifically the Tri-Ridged Wavguide (TRWG). The modal properties of these structures show high single-mode bandwidth, which presents an opportunity to check for viability in radio astronomy applications. To en-able such a study, an algorithm was developed to track and identify the modes in TRWG by using CST - a commercial three-dimensional electromagnetic analysis package. With the results of this algorithm, a modal analysis is presented for TRWGs. On this basis, a TRWG Orthomode Transducer (OMT) is designed to be cascaded with a Tri-Ridged Flared Horn (TRFH) to show that the fundamental mode will propagate with a high single-mode bandwidth. A goal function based on an S-parameter analysis for the reflection coefficient optimisation is also found. The TRWG OMT features a reference port that can be used for gain calibrations. The best result for this TRWG OMT is a maximum of −10 dB reflection coefficient across a 1.2 − 3.5 GHz bandwidth. The mode tracking algorithm is also used for a modal analysis of the TRFH. The TRFH is designed and optimised for maximum receiving sensitivity, by using existing methods and techniques used for other antennas in radio astronomy. The optimised TRFH showed a reflection coefficient of −20 dB when a perfect OMT is used in CST. When including the OMT, the maximum receiving sensitivity of 15 m2/K achieved on the shaped ngVLA reflector remains unchanged.","abstract_has_math":false,"creators":["Du Toit, Zainodean"],"institution":"Stellenbosch : Stellenbosch University","degree_name":null,"degree_level":null,"degree_discipline":null,"degree_department":null,"school":null,"contributors":[],"advisors":["De Villiers, I. L.","Lehmensiek, Robert"],"committee_chairs":[],"committee_members":[],"year":2026,"date_issued":"2026-03","date_published":"2026-03","updated_at":"2026-07-24T04:40:12Z","subjects":[],"languages":["en"],"rights":[],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"https://scholar.sun.ac.za/handle/10019.1/135783","outbound_label":"Repository record","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.advisor","label":"Advisor","values":["De Villiers, I. L.","Lehmensiek, Robert"]},{"key":"dc:contributor.other","label":"Dc Contributor Other","values":["Stellenbosch University. Faculty of Engineering. Dept. of Electrical & Electronic Engineering."]},{"key":"dc:creator","label":"Author","values":["Du Toit, Zainodean"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.accessioned","label":"Dc Date Accessioned","values":["2026-04-10T08:55:57Z"]},{"key":"dc:date.available","label":"Dc Date Available","values":["2026-04-10T08:55:57Z"]},{"key":"dc:date.issued","label":"Date","values":["2026-03"]},{"key":"dc:publisher","label":"Institution","values":["Stellenbosch : Stellenbosch University"]},{"key":"dc:type","label":"Dc Type","values":["Thesis"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language.iso","label":"Language (ISO)","values":["en"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.uri","label":"Identifier URI","values":["https://scholar.sun.ac.za/handle/10019.1/135783"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["Thesis (PhD)--Stellenbosch University, 2026.","Du Toit, Z. 2026. A Tri-Ridged Flared Horn for Radio Astronomy Applications. Unpublished doctoral dissertation. Stellenbosch: Stellenbosch University [online]. Available: https://scholar.sun.ac.za/items/a7ac1759-f085-4436-8596-bc4d1752c1d4"]},{"key":"dc:description.abstract","label":"Abstract","values":["The research in this dissertation covers the modal analysis of three-fold symmetric structures, specifically the Tri-Ridged Wavguide (TRWG). The modal properties of these structures show high single-mode bandwidth, which presents an opportunity to check for viability in radio astronomy applications. To en-able such a study, an algorithm was developed to track and identify the modes in TRWG by using CST - a commercial three-dimensional electromagnetic analysis package. With the results of this algorithm, a modal analysis is presented for TRWGs. On this basis, a TRWG Orthomode Transducer (OMT) is designed to be cascaded with a Tri-Ridged Flared Horn (TRFH) to show that the fundamental mode will propagate with a high single-mode bandwidth. A goal function based on an S-parameter analysis for the reflection coefficient optimisation is also found. The TRWG OMT features a reference port that can be used for gain calibrations. The best result for this TRWG OMT is a maximum of −10 dB reflection coefficient across a 1.2 − 3.5 GHz bandwidth. The mode tracking algorithm is also used for a modal analysis of the TRFH. The TRFH is designed and optimised for maximum receiving sensitivity, by using existing methods and techniques used for other antennas in radio astronomy. The optimised TRFH showed a reflection coefficient of −20 dB when a perfect OMT is used in CST. When including the OMT, the maximum receiving sensitivity of 15 m2/K achieved on the shaped ngVLA reflector remains unchanged."]},{"key":"dc:title","label":"Title","values":["A Tri-Ridged Flared Horn for Radio Astronomy Applications"]}]}],"canonical_facts":{"dc:contributor.advisor":["De Villiers, I. L.","Lehmensiek, Robert"],"dc:contributor.other":["Stellenbosch University. Faculty of Engineering. Dept. of Electrical & Electronic Engineering."],"dc:creator":["Du Toit, Zainodean"],"dc:date.accessioned":["2026-04-10T08:55:57Z"],"dc:date.available":["2026-04-10T08:55:57Z"],"dc:date.issued":["2026-03"],"dc:description":["Thesis (PhD)--Stellenbosch University, 2026.","Du Toit, Z. 2026. A Tri-Ridged Flared Horn for Radio Astronomy Applications. Unpublished doctoral dissertation. Stellenbosch: Stellenbosch University [online]. Available: https://scholar.sun.ac.za/items/a7ac1759-f085-4436-8596-bc4d1752c1d4"],"dc:description.abstract":["The research in this dissertation covers the modal analysis of three-fold symmetric structures, specifically the Tri-Ridged Wavguide (TRWG). The modal properties of these structures show high single-mode bandwidth, which presents an opportunity to check for viability in radio astronomy applications. To en-able such a study, an algorithm was developed to track and identify the modes in TRWG by using CST - a commercial three-dimensional electromagnetic analysis package. With the results of this algorithm, a modal analysis is presented for TRWGs. On this basis, a TRWG Orthomode Transducer (OMT) is designed to be cascaded with a Tri-Ridged Flared Horn (TRFH) to show that the fundamental mode will propagate with a high single-mode bandwidth. A goal function based on an S-parameter analysis for the reflection coefficient optimisation is also found. The TRWG OMT features a reference port that can be used for gain calibrations. The best result for this TRWG OMT is a maximum of −10 dB reflection coefficient across a 1.2 − 3.5 GHz bandwidth. The mode tracking algorithm is also used for a modal analysis of the TRFH. The TRFH is designed and optimised for maximum receiving sensitivity, by using existing methods and techniques used for other antennas in radio astronomy. The optimised TRFH showed a reflection coefficient of −20 dB when a perfect OMT is used in CST. When including the OMT, the maximum receiving sensitivity of 15 m2/K achieved on the shaped ngVLA reflector remains unchanged."],"dc:identifier.uri":["https://scholar.sun.ac.za/handle/10019.1/135783"],"dc:language.iso":["en"],"dc:publisher":["Stellenbosch : Stellenbosch University"],"dc:title":["A Tri-Ridged Flared Horn for Radio Astronomy Applications"],"dc:type":["Thesis"]},"updated_at":"2026-07-24T04:40:12Z"}