Der 60 GHz Indoor-Funkkanal - Herausforderungen menschlicher Abschattung

Driven by the ever increasing capacity of storage devices and HD video streaming applications, there will be a strong demand for wireless multi-Gbps consumer applications soon. Due to its large available bandwidth and the high allowed transmit power, the unlicensed frequency range around 60 GHz is proving ideal for the realization of such systems. During the development process of 60 GHz multi-gigabit wireless systems, a detailed knowledge of the radio channel is essential. Taking into account research gaps, this dissertation makes a significant contribution to knowledge in the field of 60 GHz channel characterization. The focus is on human shadowing and its influence on the channel characteristics, which leads to a high and time-variant path loss. In order to provide realistic results, sophisticated radio channel models are required for the 60 GHz range. In particular, they should include information in the spatial domain at the receiver and the transmitter as well as take into account time-varying human shadowing. The angular information is necessary in this case to evaluate smart antenna systems. Such comprehensive models are not yet available and therefore represent the major outcome of this dissertation.Wegen seiner großen verfügbaren Bandbreite und der hohen erlaubten Sendeleistung erweist sich der unlizensierte Frequenzbereich um 60 GHz als hervorragend geeignet für die Realisierung drahtloser Multi-Gigabit-Kommunikationssysteme. Während des Entwicklungsprozesses solcher Systeme ist eine detaillierte Kenntnis des Funkkanals unerlässlich. Unter Berücksichtigung offener Fragestellungen leistet die vorliegende Dissertation einen wesentlichen Beitrag zum Wissensstand auf dem Gebiet der 60-GHz-Kanalcharakterisierung. Im Vordergrund steht dabei die Abschattung durch Personen, die bei Trägerfrequenzen um 60 GHz zu einer hohen und gleichzeitig zeitvarianten Funkfelddämpfung führt. Um realistische Ergebnisse zu liefern, sind im 60-GHz-Bereich komplexe Funkkanalmodelle erforderlich, die insbesondere Winkelinformationen am Sender und Empfänger enthalten und die zeitvariante Abschattung durch Personen berücksichtigen sollten. Beides ist notwendig, um intelligente Antennensysteme evaluieren zu können. Solche umfassenden Modelle sind bisher nicht verfügbar und stellen deshalb das wesentliche Ziel dieser Dissertation dar

Beam scanning by liquid-crystal biasing in a modified SIW structure

A fixed-frequency beam-scanning 1D antenna based on Liquid Crystals (LCs) is designed for application in 2D scanning with lateral alignment. The 2D array environment imposes full decoupling of adjacent 1D antennas, which often conflicts with the LC requirement of DC biasing: the proposed design accommodates both. The LC medium is placed inside a Substrate Integrated Waveguide (SIW) modified to work as a Groove Gap Waveguide, with radiating slots etched on the upper broad wall, that radiates as a Leaky-Wave Antenna (LWA). This allows effective application of the DC bias voltage needed for tuning the LCs. At the same time, the RF field remains laterally confined, enabling the possibility to lay several antennas in parallel and achieve 2D beam scanning. The design is validated by simulation employing the actual properties of a commercial LC medium