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Efficient Computation of the Near-Field Mutual Coupling Between Antennas on Vehicles
KTH, School of Electrical Engineering (EES), Electromagnetic Engineering. (TET)ORCID iD: 0000-0001-7812-9849
2014 (English)Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
Abstract [en]

A near-eld generalization of Friis transmission equation has previously been proposed in the literature. Using this generalization, it is possible to calculatethe mutual coupling between two antennas as a weighted integral over the antenna far-fields. In this thesis, a change of variables is used to remove the singularity in the integrand and a normalization of the antenna far-field is suggested to take mismatch and thermal losses into account. The resulting non-singular integral has been implemented in a computer program that can be used to calculate the mutual coupling between two arbitrarily polarized antennas given the antenna far-fields and the geometrical separation between the antennas. The program has several advantages compared to previous programs based on the near-field generalization of Friis transmission equation. Firstly, this program can calculate the mutual coupling between two arbitrarily polarized and oriented antennas whereas previous programs could only be used for linearly polarized and polarization-matched antennas. Secondly, the advantage of the non-singular form is the improved numerical stability. The mutual coupling calculated using this program is demonstrated to agree well with results from full three-dimensional simulations of antennas located in each others near-fields using commercial software. Finally, we investigate for the first time if this integral relation can be used to calculate approximate values of the mutual coupling between antennas on an electrically large vehicle.

Abstract [sv]

En närfältsgeneralisering av Friis transmissionsekvation har tidigare foreslagits i litteraturen. Med denna generalisering kan den ömsesidiga kopplingen mellan två antenner beraknas som en viktad integral over antennernas fjärrfältsamplituder. I denna rapport används ett variabelbyte för att ta bort singulariteten i integranden och en normering av fjärrfaltsamplituden föreslås for att ta hänsyn till antennernas förluster. Den resulterande icke-singulära integralen har implementerats i ett datorprogram som kan användas for att beräkna kopplingenmellan två godtyckligt polariserade antenner givet antennernas fjärrfältsamplituder och geometriska separation. Programmet har flera fördelar jämfört med tidigare program som baserats på närfältsgeneraliseringen av Friis transmissionsekvation. För det första kan detta program anvandas för att beräkna kopplingen mellan två godtyckligt polariserade och orienterade antenner då tidigare program har varit skrivna for linjarpolariserade och polarisationsmatchade antenner. Dessutom uppnås en högre numerisk stabilitet eftersom den ickesingulära formen av integralen används. Det demonstreras i flera exempel att kopplingen som beräknats med detta program för antenner som befinner sig i varandras närfält stämmer väl överens med resultat som beräknats med kommersiell mjukvara. Avslutningsvis undersöks om denna närfältsgeneralisering kan användas for att approximativt beräkna kopplingen mellan två antenner på en elektriskt stor farkost.

Place, publisher, year, edition, pages
2014. , 64 p.
, XR-EE-EE 2014:02
Keyword [en]
coupling, near-field, antennas
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
URN: urn:nbn:se:kth:diva-146903OAI: diva2:726393
Educational program
Master of Science in Engineering - Electrical Engineering
2014-06-13, Seminarierummet, Teknikringen 33, Stockholm, 14:00 (English)
Available from: 2014-07-14 Created: 2014-06-18 Last updated: 2014-07-14Bibliographically approved

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