Browsing by Author "Richter, Juergen"
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- A deconvolution method to remove distortion caused by antenna radiation pattern from measurementPublication . Cui, Huajian; Caldeirinha, Rafael; Richter, JuergenThe influence of vegetation on radiowave signals has become an important aspect of the design of wireless communication links. In recent years the theory of Radiative Energy Transfer has been adopted as a reliable tool to predict the radiowave propagation through and near vegetation. However one major factor influencing accuracy of the measurement is the radiation pattern of the receiver antenna. The measured pattern will be the convolution product of the antenna radiation pattern and the phase function of the vegetation medium. The measured pattern therefore needs to undergo a deconvolution process before enable to provide reliable information. This paper presents a deconvolution method developed using optimum compensation filtering to remove the distortion caused by the receiver antenna radiation pattern. A pre-filtering technique using auto/cross-correlation is utilised to improve the deconvolution results, as well as an error function is deployed to determine the optimal parameter in the iterative filter.
- Investigation of a Radio Propagation Model for Vegetation Scatter Dynamic Channels at BFWA FrequenciesPublication . Morgadinho, Sérgio; Richter, Juergen; Caldeirinha, Rafael F. S.; Fernandes, Telmo R.The successful deployment of wireless technologies in the micro- and millimetre frequencies relies on the understanding of radio channel propagation and accurate radio propagation models. To this extent, the dynamic effects of vegetation on radio signals are investigated, as a function of wind direction, receiver location and vegetation depth. Furthermore, a radio propagation model, based on the RET, is investigated as an approach to predict the channel dynamic effects of vegetation scatter at 20 GHz. The model is evaluated for a structured forest medium, and its performance is assessed through the use of primary, secondary and error quantification statistics.
- Investigation of a time-variant dRET model in vegetation: XXIXth URSI general assembly to be held in Chicago, IL, USA, August 7–16, 2008Publication . Morgadinho, Sergio; Richter, Juergen; Caldeirinha, Rafael; Fernandes, Telmo, Telmo Rui Carvalhinho Cunha, Telmo R.In this paper, the discrete Radiative Energy Transfer is investigated as an effective mean to model wind induced time-variant vegetative radio channels. The investigated model will make use of the input parameters time-variation properties to achieve channel dynamics modeling. Analysis of both the foliated channel statistics and model performance against measured data, at 20 GHz, will be presented.