The Butler Matrix as a multiple beam beamforming network

Boning, Pieter (2020-03)

Thesis (MEng)--Stellenbosch University, 2020.

Thesis

ENGLISH ABSTRACT: High bandwidth communication has become an essential part of modern society. The increasing demand for data requires engineers to implement innovative solutions to utilise the finite electromagnetic spectrum. Methods such as time, frequency, and spatial division have been adopted to increase the effective use of the spectrum. Time and frequency-division reduces the amount of bandwidth, the property that needs to be maximised, available to a single user. To implement spatial division efficiently and cost-effectively is a complex problem which has received a lot of attention lately as communication devices are now more than ever, accessible to the average person. To address the spatial division problem, multiple beam beamforming networks (MBBFN) is the suggested solution, but are expensive and technically difficult to implement. There is a direct correlation between the proposed Butler Matrix and the Fast Fourier Transform, in that both are an optimal solution to the underlying calculation, requiring the least amount of operations. In the case of the Butler Matrix, these operations refer to power dividers and combiners, and phase shifters. This poses a viable solution in terms of efficiency and cost-effectiveness. There are many implementations of the Butler Matrix, two of which are analysed, constructed, and measured. One implementation was done at a higher frequency to effectively increase the operational bandwidth. The higher frequency posed significant challenges resulting in unacceptable performance degradation, but still proved a working concept. The lower frequency implementation was easier to design and implement with very low cost, and successfully demonstrated the ability of the Butler Matrix as a MBBFN. The theoretical analysis of the Butler Matrix concept provides a better understanding of MBBFN’s, which is supported by simulated and measured results.

AFRIKAANSE OPSOMMING: Kommunikasie met ’n hoë bandwydte is ’n wesenlike deel van die moderne samelewing. Die toenemende vraag na data, vereis dat ingenieurs innoverende oplossings moet implementeer om die eindige elektromagnetiese spektrum te gebruik. Metodes soos tyd, frekwensie en ruimtelike verdeling word toegepas om die effektiewe gebruik van die spektrum te verhoog. Tyd en frekwensieverdeling verminder die hoeveelheid bandwydte, die eienskap wat gemaksimeer moet word, wat beskikbaar is vir ’n enkele gebruiker. Om ruimtelike verdeling doeltreffend en koste-effektief te implementeer, is ’n ingewikkelde probleem wat die afgelope tyd baie aandag geniet, aangesien kommunikasietoestelle nou meer as ooit tevore vir die gemiddelde persoon toeganklik is. Om die ruimtelike verdeling probleem aan te spreek, is meervoudige stralingsvormende netwerke (MSVN) die verkose oplossing, maar is duur en tegnies moeilik om te implementeer. Daar is ’n direkte verband tussen die voorge-stelde Butler Matriks en die Vinnige Fourier-transformasie, deurdat beide ’n optimale oplossing vir die onderliggende berekening is, wat die minste hoeveel-heid bewerkings benodig. In die geval van die Butler Matriks, verwys hierdie bewerkings na kragverdelers, kragkombineerders en faseverskuiwings. Dit bied ’n haalbare oplossing ten opsigte van doeltreffendheid en koste-effektiwiteit. Daar is baie implementerings van die Butler Matriks, waarvan twee ontleed, gekonstrueer en gemeet word. Een implementering is met ’n hoër frekwensie gedoen om die operasionele bandwydte effektief te verhoog. Die hoër frekwensie het uitdagings opgelewer wat tot onaanvaarbare agteruitgang van verrigting gelei het, maar kon steeds ’n werkende konsep illustreer. Die implementering van die laer frekwensie was makliker om te ontwerp en met baie lae koste te implementeer en het die vermoë van die Butler Matriks as ’n MSVN suksesvol getoon. Die teoretiese analise van die Butler Matriks-konsep bied ’n beter begrip van MSVN’s, wat ondersteun word deur gesimuleerde en gemete resultate.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/107827
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