Compact antenna arrays in mobile communications

Transkript

1 Compact antenna arrays in mobile communications A quantitative analysis of radiator coupling Christian Volmer Universitätsverlag Ilmenau 2010

2 Impressum Bibliografische Information der Deutschen Nationalbibliothek Die Deutsche Nationalbibliothek verzeichnet diese Publikation in der Deutschen Nationalbibliografie; detaillierte bibliografische Angaben sind im Internet über abrufbar. Diese Arbeit hat der Fakultät für Elektrotechnik und Informationstechnik der Technischen Universität Ilmenau als Dissertation vorgelegen. Tag der Einreichung: 20. März Gutachter: Univ.-Prof. Dr. rer. nat. habil. Matthias A. Hein (Technische Universität Ilmenau) 2. Gutachter: Univ.-Prof. Dr.-Ing. habil. Reiner S. Thomä (Technische Universität Ilmenau) 3. Gutachter: Univ.-Prof. Dr.-Ing. Klaus Solbach (Universität Duisburg-Essen) Tag der Verteidigung: 26. November 2009 Technische Universität Ilmenau/Universitätsbibliothek Universitätsverlag Ilmenau Postfach Ilmenau Herstellung und Auslieferung Verlagshaus Monsenstein und Vannerdat OHG Am Hawerkamp Münster ISSN (Druckausgabe) ISBN (Druckausgabe) urn:nbn:de:gbv:ilm Titelfoto: photocase.com AlexFlint

3 1 Introduction 1 2 Power considerations at multi-port antennas Earlier work Eigenmode description of lossless arrays Single-port antenna matching efficiency Generalisation to multi-port antennas The fundamental modes of radiation Reflections of eigenmodes Eigenmode far-field patterns Far-field patterns and the radiation matrix Beam-pattern orthogonalisation Non-distinct eigenefficiencies Ohmic array losses An equivalent circuit for lossless arrays Examples of the consequences of radiator coupling Analysis of a manufacturedλ 0 /10 three-port array Influence of number of radiators and separation Summary Decoupling and matching networks General conditions for decoupling and matching Decoupling by eigenmode excitation Directional couplers as decoupling networks Example: symmetric two-port antenna array xiii

4 xiv Example: symmetric three-port antenna array A systematic design procedure for decoupling networks Two-element decoupling Decoupling across a symmetry plane Radiator merging Eigenmode matching Efficiency considerations Example implementations Linearλ 0 /4 three-port array LTCC implementation of a three-port DMN Broadband matched two-port array Circularλ 0 /10 four-port array Summary Diversity reception with compact antenna arrays Overview and past work Figures of merit for correlated fading A simplified diversity model Array gain of a mutually coupled array Diversity gain over a single receive antenna Diversity loss over an ideal antenna array Extensions to the diversity model Influence of the communications environment Effects of a decoupling and matching network Spatially coloured receiver noise A complete receiver model Antenna array noise Network noise Front-end amplifier noise Discussion of the front-end model Summary Compact antenna arrays in practice: a diversity receiver Overview of the diversity system The transmitter The receiver front-end Baseband processing

5 xv The graphical user interface Benefits of decoupling and matching networks Verification of the diversity figures of merit Measurements of the signal envelope covariance matrix Front-end noise characterisation Noise characterisation of a single receiver-branch Noise characterisation of the multi-port receiver Influence of noise on the SNR diversity gain Summary Summary and outlook Zusammenfassung und Ausblick 197 A Proofs and derivations 205 A.1 Diagonalisation of eigen-reflections A.2 Ohmic eigenefficiencies and DMNs A.3 Matrix-form of a single-port matching network A.4 Matrix-form of a decoupling and matching network A.5 Eigenmodes fade independently A.6 Series expansion of the diversity gain B Waves, scattering parameters, and noise 219 B.1 Scattering parameters B.1.1 Definition B.1.2 Interconnection of multi-port junctions B.1.3 Renormalisation B.2 Noise wave description Bibliography 231 Notation and abbreviations 247