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Wideband antenna design for time domain measurements in a reverberation chamber
Thesis (MEng)--Stellenbosch University, 2023.
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| Format: | Thesis |
| Language: | en_ZA en_ZA |
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Stellenbosch : Stellenbosch University
2023
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| _version_ | 1867613810213257216 |
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| access_status_str | Open Access |
| author | Snyman, Sandra |
| author2 | Gilmore, Jacki |
| author_browse | Gilmore, Jacki Snyman, Sandra |
| author_facet | Gilmore, Jacki Snyman, Sandra |
| author_sort | Snyman, Sandra |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Thesis (MEng)--Stellenbosch University, 2023. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/129037 |
| institution | Stellenbosch University (South Africa) |
| language | en_ZA en_ZA |
| last_indexed | 2026-06-10T12:42:03.173Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2023 |
| publishDateRange | 2023 |
| publishDateSort | 2023 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/129037 Wideband antenna design for time domain measurements in a reverberation chamber Snyman, Sandra Gilmore, Jacki Stellenbosch University. Faculty of Engineering. Dept. of Electrical and Electronic Engineering. Radio -- Interference -- Measurement Ultra-wideband antennas Radio astronomy Square Kilometer Array Broadband communication systems Thesis (MEng)--Stellenbosch University, 2023. ENGLISH ABSTRACT: Radio Frequency Interference is a serious threat to any radio astronomy undertaking. This includes the Square Kilometer Array, a radio telescope which will be located in part in South Africa. One way in which the effect of RFI is mitigated at the South African SKA site is by doing thorough RFI qualification measurements on all electronic equipment which will be used on site. These RFI measurements are typically carried out in the frequency domain, but the measurement time can be drastically reduced by carrying out the measurements in the time domain instead. In addition to performing measurements in a test environment, a time domain RF receiver system can also be used on site, in order to capture short RF pulses that originate from site infrastructure and the surrounding area. As part of a time domain RFI measurement system, a wideband antenna that can handle pulsed time domain signals is required. This type of antenna is typically categorised as an Ultra Wideband (UWB) antenna. Time domain distortion is introduced by unstable antenna performance over frequency, specifically with regard to variation in antenna phase response in the frequency band of interest. The Vivaldi antenna design is one that can be used over a wide range of frequencies and has a stable linear phase response due to its smooth profile. A Vivaldi antenna is designed in this thesis to be used in a frequency band from 50MHz to 6 GHz. The antenna performance is simulated in CST and two identical antennas are fabricated. The time domain performance of the antenna design is investigated through transmission measurements of a two-antenna system. The antenna shows good time domain behaviour with little dispersion. Transmission measurements are also carried out on pairs of horn antennas, LPDAs, and asymptotic conical dipole antennas, as well as on combinations between these different antenna types. This investigates the effect that different antenna designs have on time domain pulses, specifically attempting to explore the time-derivative relationship between an antenna’s transmitting and receiving transfer functions. From the transmission measurements that were carried out, the Vivaldi antenna pair shows a system fidelity factor of 0.97, indicating an excellent match between input signal and received signal. This is a clear improvement from the LPDA antenna, which the Vivaldi design intends to replace in the RFI measurement system and which severly disperses the input pulse beyond recognition. This result indicates that the designed antenna is a good candidate for use in time domain RFI measurents. AFRIKAANSE OPSOMMING: Radiofrekwensie-inmenging (RFI) is ’n ernstige bedreiging vir enige radio-sterrekunde-onderneming. Dit sluit die Square Kilometer Array in, ’n radioteleskoop wat gedeeltelik in Suid-Afrika geleë sal wees. Een manier waarop die effek van RFI by die Suid-Afrikaanse SKA-terrein aangespreek word, is deur deeglike RFIkwalifikasiemetings uit te voer op alle elektroniese toerusting wat op die terrain gebruik sal word. Hierdie RFI-metings word tipies in die frekwensiegebied uitgevoer, maar die metingstyd kan drasties verminder word deur eerder die metings in die tydgebied uit te voer. Saam met die uitvoering van RFI-kwalifikasiemetings in ’n toetsomgewing kan ’n tydgebied RF-ontvangerstelsel ook op die SKA-terrein gebruik word, om kort RF-pulse op te vang wat afkomstig is van terreininfrastruktuur en die omliggende area. As deel van ’n tydgebied RFI-metingstelsel word ’n wyebandantenna benodig wat tydgebied pulsseine kan hanteer. Hierdie tipe antenna word tipies gekategoriseer as ’n Ultra Wideband (UWB) antenna. Tydgebiedvervorming word ingestel deur onstabiele antennagedrag oor frekwensie, spesifiek met betrekking tot variasie in antennafaserespons in die frekwensieband van belang. Die Vivaldi-antennaontwerp is een wat oor ’n wye reeks frekwensies gebruik kan word en het ’n stabiele lineêre faserespons as gevolg van sy gladde profiel. ’n Vivaldi-antenna is in hierdie tesis ontwerp om in ’n frekwensieband van 50MHz tot 6 GHz gebruik te word. Die antennagedrag is in CST gesimuleer en twee identiese antennas is vervaardig. Die tydgebiedgedrag van die antennaontwerp is ondersoek met behulp van transmissiemetings van ’n twee-antennaiv stelsel. Die antenna toon goeie tydgedbiedgedrag met min verspreiding, soos bepaal deur ’n hoë trouheidsfaktor in transmissie en ontvangs. Transmissiemetings word ook uitgevoer op pare horingantennas en LPDA’s, sowel as op kombinasies tussen hierdie verskillende antennatipes, en word dan na die tydgebied getransformeer. Dit ondersoek die effek wat verskillende antennaontwerpe op tydgebied-impulse het, en poog spesifiek om die tydafgeleide verhouding tussen ’n antenna se ordrag- en ontvangsfunksies te ondersoek. Vanuit die transmissiemetings wat uitgevoer is toon die Vivaldi-antennapaar ’n stelselgetrouheidsfaktor van 0.97, wat ’n uitstekende ooreenstemming tussen insetsein en ontvangsein aandui. Dit is ’n duidelike verbetering van die LPDAantenna, wat die Vivaldi-ontwerp beoog om te vervang in die RFI-metingstelsel, wat die insetpuls onherkenbaar versprei. Hierdie resultaat dui aan dat die ontwerpte antenna ’n goeie kandidaat is vir gebruik in tyddomein RFI-metings. Masters 2023-11-20T09:41:58Z 2024-01-08T20:06:48Z 2023-11-20T09:41:58Z 2024-01-08T20:06:48Z 2023-12 Thesis https://scholar.sun.ac.za/handle/10019.1/129037 en_ZA en_ZA Stellenbosch University xiv, 105 page : illustrations application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Radio -- Interference -- Measurement Ultra-wideband antennas Radio astronomy Square Kilometer Array Broadband communication systems Snyman, Sandra Wideband antenna design for time domain measurements in a reverberation chamber |
| title | Wideband antenna design for time domain measurements in a reverberation chamber |
| title_full | Wideband antenna design for time domain measurements in a reverberation chamber |
| title_fullStr | Wideband antenna design for time domain measurements in a reverberation chamber |
| title_full_unstemmed | Wideband antenna design for time domain measurements in a reverberation chamber |
| title_short | Wideband antenna design for time domain measurements in a reverberation chamber |
| title_sort | wideband antenna design for time domain measurements in a reverberation chamber |
| topic | Radio -- Interference -- Measurement Ultra-wideband antennas Radio astronomy Square Kilometer Array Broadband communication systems |
| url | https://scholar.sun.ac.za/handle/10019.1/129037 |
| work_keys_str_mv | AT snymansandra widebandantennadesignfortimedomainmeasurementsinareverberationchamber |