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Full-Text Articles in Engineering
Aeronautical Telemetry Using Multiple-Antenna Transmitters, Michael A. Jensen, Michael D. Rice, Adam L. Anderson
Aeronautical Telemetry Using Multiple-Antenna Transmitters, Michael A. Jensen, Michael D. Rice, Adam L. Anderson
Faculty Publications
The placement of multiple antennas on an air vehicle is one possible practice for overcoming signal obstruction created by vehicle maneuvering during air-to-ground transmission. Unfortunately, for vehicle attitudes where more than one of these antennas has a clear path to the receiving station, this practice also leads to self-interference nulls, resulting in dramatic degradation in the average signal integrity. This paper discusses application of unitary space-time codes such as the Alamouti transmit diversity scheme and unitary differential space-time codes to overcome the self-interference effect observed in such systems. The mathematical foundations of these techniques within the context of this application …
Analysis Of Electromagnetic Field Polarizations In Multi-Antenna Systems, Michael A. Jensen, Jon W. Wallace, Thomas Svantesson
Analysis Of Electromagnetic Field Polarizations In Multi-Antenna Systems, Michael A. Jensen, Jon W. Wallace, Thomas Svantesson
Faculty Publications
This paper provides an analytical framework useful for assessing the use of all six electric and magnetic electromagnetic field polarizations for multiantenna communications systems. The approach uses a mapping between the induced signal currents and the received electromagnetic field in order to formulate a diversity interpretation of the six-polarization problem. Application of the framework to a simple, yet representative, channel model demonstrates that for full multipath elevation and azimuthal angle spread, six communication modes are theoretically possible. However, to implement the system requires more antenna design work since a straightforward implementation is found to reduce the potential number of modes …
Termination-Dependent Diversity Performance Of Coupled Antennas: Network Theory Analysis, Michael A. Jensen, Jon W. Wallace
Termination-Dependent Diversity Performance Of Coupled Antennas: Network Theory Analysis, Michael A. Jensen, Jon W. Wallace
Faculty Publications
A new analysis of mutually coupled diversity antenna systems is presented that includes the effects of coupling on the radiation pattern and received power. This analysis, based upon the network scattering parameters, makes use of the singular value decomposition to both specify the characteristics of and analyze terminated antenna networks. The approach facilitates a simplified proof of the multiport conjugate matching condition as well as development of expressions for diversity performance as a function of various impedance terminations. Application of the analysis to coupled dipole antennas characterized using full-wave electromagnetic analysis leads to a comprehensive examination of the diversity performance …
Modeling The Statistical Time And Angle Of Arrival Characteristics Of An Indoor Multipath Channel, Michael A. Jensen, Brian D. Jeffs, A. Lee Swindlehurst, Quentin H. Spencer
Modeling The Statistical Time And Angle Of Arrival Characteristics Of An Indoor Multipath Channel, Michael A. Jensen, Brian D. Jeffs, A. Lee Swindlehurst, Quentin H. Spencer
Faculty Publications
Most previously proposed statistical models for the indoor multipath channel include only time of arrival characteristics. However, in order to use statistical models in simulating or analyzing the performance of systems employing spatial diversity combining, information about angle of arrival statistics is also required. Ideally, it would be desirable to characterize the full spare-time nature of the channel. In this paper, a system is described that was used to collect simultaneous time and angle of arrival data at 7 GHz. Data processing methods are outlined, and results obtained from data taken in two different buildings are presented. Based on the …
Performance Analysis Of Antennas For Hand-Held Transceivers Using Fdtd, Michael A. Jensen, Yahya Rahmat-Samii
Performance Analysis Of Antennas For Hand-Held Transceivers Using Fdtd, Michael A. Jensen, Yahya Rahmat-Samii
Faculty Publications
The design of antennas for hand-held communications devices depends on the implementation of simulation tools that can accurately model general topologies. The paper presents the analysis of small antennas mounted on hand-held transceivers using the finite-difference time-domain (FDTD) method. The key features of the FDTD implementation are discussed, with particular emphasis placed upon modeling of the source region. The technique is used to predict the gain patterns and broadband input impedance behavior of monopole, planar inverted F, and loop antenna elements mounted on the handset. Effects of the conducting handset chassis, the plastic casing around the device, and lumped elements …
Characterization Of Electromagnetically Coupled Superquadric Loop Antennas For Mobile Communications Applications, Michael A. Jensen, Yahya Rahmat-Samii
Characterization Of Electromagnetically Coupled Superquadric Loop Antennas For Mobile Communications Applications, Michael A. Jensen, Yahya Rahmat-Samii
Faculty Publications
Analysis of two mutually coupled loop antennas with arbitrary relative orientation and position and possibly different geometries is presented. The antennas are represented by generalised superquadric curves, which include circular, elliptical, and rectangular loop geometries, and they may be located either in a homogeneous region or next to an infinite ground plane. A Galerkin-type moment method with piecewise sinusoidal subsectional basis and weighting functions is used. Special consideration is given to implement the solution using curved wire segments instead of the commonly employed linear segments to improve computational efficiency. This very general computational tool is used to investigate the behaviour …