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A 2D Indoor Propagation Model Based on Waveguiding, Mode Matching and Cascade Coupling
KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
2012 (English)Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
Abstract [en]

In this thesis a theoretical model for indoor propagation in a straight corridor with adjacent rooms is developed and evaluated. One objective is to assess the effect of different conductivities and permittivities in the walls between rooms have on the power levels, in both the corridor and the rooms. Furthermore, a model of a leaky cable is proposed for which the corresponding propagation characteristics are evaluated and compared to that of a dipole antenna to assess if a leaky cable is a viable alternative for radio coverage in an indoor environment. In order to evaluate the model, a wideband measurement campaign has been conducted at 2.44 GHz with a 40 meter long leaky coaxial cable and two vertically polarized dipole antennas.

The proposed model is based on the waveguide model in 2D, the mode matching method and cascade coupling of scattering matrices. A section of a corridor is modeled as waveguides with different cross section where one waveguide contains a dielectric medium which models the wall between two rooms. Mode matching is used to determine how the waveguide modes are coupled at the boundaries between the waveguides and the result is collected in a scattering matrix. Multiple corridor sections are then connected together, by cascade coupling the corresponding scattering matrices of each section, into a long corridor with adjacent rooms. Point sources are used to excite the waveguides as an approximation of dipole transmitting antennas. Moreover, the radiating slots in the leaky cable are modeled by multiple point sources that are phase and amplitude shifted in order to achieve the same radiation direction and longitudinal loss as the leaky cable. Finally, the inverse discreet Fourier transform is applied to the wideband electromagnetic field distribution in order to determine the propagation characteristics in the time domain.

The results from the model are in good quantitative agreement with the measurement data, and it is shown that a leaky cable give a more even radio coverage in an office corridor compared to a dipole antenna, especially when the internal walls are highly reflective. Moreover, it is shown that the direct path is dominating for transmission between rooms with transparent walls, like plasterboard, while the main propagation path for highly reflective walls is along the corridor.

Place, publisher, year, edition, pages
2012. , 95 p.
EES Examensarbete / Master Thesis, XR-EE-ETK 2012:007
Keyword [en]
Indoor propagation, waveguide model, mode matching, cascade coupling
National Category
Engineering and Technology
URN: urn:nbn:se:kth:diva-98849OAI: diva2:539524
Educational program
Master of Science in Engineering - Electrical Engineering
Available from: 2012-07-04 Created: 2012-07-04 Last updated: 2012-07-06Bibliographically approved

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