In a previous paper [1], we investigated the worst-case scenario of the influence of atmospheric circumstances on the propagation of microwave links. In this document, we will investigate this problem from a statistical point of view. This allows quantifying the probability of unlikely events to happen, and their impact on the quality of the transmission.

The measurement of NO2 abundance in the air is of interest for monitoring pollution sources and air quality. A new instrumental concept has been recently introduced, which makes use of an acoustooptical tunable filter (AOTF) as the main component of a spectral imager. With the capability of resolving the absorption spectrum of NO2, and a high spatial and temporal sampling, this instrument can be seen as a NO2 camera. In this instrument, the selection of different optical wavelengths by the AOTF is done by applying a radio frequency (RF) signal to the AOTF. The selected frequency and the applied amplitude are the key parameters for the quality of the measurements. The design and assembly of an RF chain, consisting of an RF generator and RF amplifier, will lead to an electronics bench capable of driving the NO2 camera. In view of a potential spaceborne application of this instrumental concept, the design of the RF generator is only making use of space-qualified components. This paper focuses on the development of this part of the electronics bench.

It is common that the national authorities impose large consultation zones around microwave links [1]. When those areas are free of obstacles there is no problem, but usually they are considered as exclusion zones. Those large zones are inspired by the fact that the obstacle for which the authorisation is requested may not be the only one, especially in the case of wind turbines. The national authorities (for Belgium BIPT/IBPT) impose limitations on the projections of the links in a horizontal plane, usually 3 times the largest size of the first Fresnel ellipsoid. In this paper we will investigate the 3D case to allow more lenient criteria to be applied.

Besides the radiation and reflection performance of wearable antennas, arguably one of the most important parameters is their Specific Absorption Rate (SAR). This work aims to evaluate SAR for wearable antennas integrated with Artificial Magnetic Conductor (AMC) plane made using different material categories - textiles and a flexible polymer,. Two types of textiles, felt and ShieldIt Super are used to build the first, textile-based antenna, while polydimethylsiloxane (PDMS) and the fluidic metal eutectic gallium indium alloy (EGaIn) are used to build the second, polymer-based antenna. Both materials are chosen due to their flexibility conformity to the human body, thus providing comfort to users. Despite the SAR for both antenna types did not exceed the European regulatory limits of 2 W/kg averaged over 10g of tissues; there are considerable differences between them.

Even if the idea is already very old (proposed first by Moseley in 1965), it offers analytical solutions of Helmholtz equations for curved waveguides. One of the key elements in their successful use is the computation of recursion formulas to find a numerical solution to the problem of analysis of generally shaped waveguides. They will be derived in this paper. Even if the original theory includes a generalisation to 3 dimensional cavities we will limit ourselves to 2 dimensional waveguide cases.

In the frame of a mission of the European Space Agency (ESA) a space qualified RF-generator needs to be developed to drive an AOTF (Acousto-Optical Tunable Filter) to make hyper-spectral images of the limb of the Earth. Custom off-the-shelf electronics can not fulfil the requirements for this scientific mission, hence alternative solutions for the RF-generation are investigated. This paper describes one of the possible solutions.

The low frequency instability in the method of moments becomes important when objects smaller than the wavelength have to be computed. For a PEC (Perfectly Electrically Conducting) body, this leads to uncoupling or splitting the integral equations by using first the MFIE (Magnetic Field Integral Equation) for the currents and consecutively the EFIE (Electric Field Integral Equation) for the charges. For dielectric bodies, the charge is reintroduced. The contribution of this paper consists in implementing an efficient technique, reducing the computational complexity, in time but mostly in memory. A toolkit has been developed to perform accurate computations. The technique has been verified quantitatively, checking the charge and current distributions against analytic solutions where existing, as well as qualitatively against the boundary conditions for the scattered field. Many examples will be given, both in frequency and in time domain (obtained by inverting frequency domain calculations including the DC (Direct Current) component).

The work reported in this paper addresses different solutions to the problem of building a space-qualified RF chain for an acousto-optical tunable filter. This research was undertaken as part of the development of the ALTIUS space mission (atmospheric limb tracker for the investigation of the upcoming stratosphere), which aims at the measurement of atmospheric trace species (ozone, nitrogen dioxid...

The car factory experienced many communication problems within their factory, due to (new) requirements of the Belgian Federal Communication authorities (BIPT) to limit the height of the antennas to 12 m above ground level. This paper deal with the challenge to guarantee a 95% in this factory, with a large amount of moving metallic parts. The solution turned out to be an array of 4 antennas complemented with an auxiliary antenna.

Air Traffic Control (ATC) and their responsible authorities have been always very sensitive to safety of the systems they are using to guarantee a fool-proof and environmentally safe operation of the facilities to provide guidance for the airplanes. This paper deals with the influence of a pulsed systems on standard air-ground aviation communication systems. A measurement campaign is described. An analysis of the inaccuracies of those measurements is performed and the influence of (shielded and unshielded) spark plug systems on aviation communication systems (still based on A(mplitude)M(odulation)) is explained in detail.

The ALTIUS-instrument is a three-channel spectral imager, measuring in the ultraviolet, visible and near infrared wavelength domains, that is bound to fly aboard a PROBA-satellite. The goal of the ALTIUS-instrument is to make hyper spectral images of the limb of the earth. In each of ALTIUS' three channels an AOTF (Acousto-Optical Tunable Filter) will be used. For each channel an RF-generator will be developed and subjected to a suite of environmental tests such as thermal-vacuum, vibration, radiation, shock and Electromagnetic Compatibility (EMC). For the AOTF RF-generator different solutions are possible. Currently the design of an analog Hilbert transform and a high frequency phase-locked loop (PLL) are proposed as possible solutions. The choice of components, the PCB-design and the manufacturing of both designs has to be done in accordance to space qualified standards. This limits the choice of design and lifts the design challenge to a higher level. Because of the limited choice of space qualified components, general commercial approaches are not possible. For this reason specific designs have to be investigated and research has to be done to select the appropriate solution. (C) 2015 Elsevier Ltd. All rights reserved.

By investigating propagation problems for wind turbines, and more in particular near-field RCS computations, we have noticed that sometimes, even stabilized MoM solutions do not behave as expected. In this paper, we will give examples of some RCS computations in different scenarios. We found out that discrepancies in some RCS values are due to the choice of the meshing. Usually, standard meshers like gmsh only take into account one object. Unfortunately, to be accurate, all the positions of all objects have to be taken into account, to allow an accurate interaction between the objects. We will go deeper into the fundamentals of the relation between the accuracy and the mesh size and shape for some canonic problems of which the solution is exactly known.

In some cases the objects like wind turbines are so large that the far-field condition are not met within the visibility of the object due to the curvature of the earth. Therefor, new ways to compute the reflections of those objects are required. This is similar to the concept of near-field communications, where the far-field gain (the normal definition) has to be replaced by the near-field gain. In some cases, we will even be able to find simple formulas for the worst case RCS in function of the relative size of the object with respect to the wavelength.

The modelling of transfer characteristics of low-voltage power distribution networks for Power Line Communications requires the knowledge of the electrical parameters of the cables comprising these networks. In this study, a method is developed for characterising the power line cable parameters. In complement to many existing approaches, the authors estimate the cable parameters from a limited set of measurements. Measurement results can take into account fabrication tolerances, bending of the cables etc., which help to obtain more accurate results. A multi-conductor powerline cable has multiple, coupled propagation modes with corresponding primary parameters. Based on multi-conductor transmission line theory, the authors propose a practical measurement approach to derive the parameters separately. A previous analysis was made for four-conductor powerline cable. Here, it will also be generalised for three-conductor cables. With the parameters, the transfer function of the same kind of cable can be obtained easily. The approach is validated by comparing the deduced transfer function of a power line cable with the directly measured one.

The low-frequency instability in the method of moments can be resolved by reformulating the underlying integral equations to explicitly include charge as an unknown. A new technique based on this charge and current formulation that reduces the computational complexity, both in time and memory, will be introduced. Considerations when using a charge and current technique include the practical problems of basis functions and the evaluation of the singular surface integrals, well as more theoretical problems such as whether the continuity equation still holds. The technique is implemented using a simple set of basis and testing functions and has been verified quantitatively, checking the charge and current distributions against analytic solutions where existing, as well as qualitatively against the boundary conditions for the scattered field. These results show the method to be both stable and accurate.

By investigating propagation problems for wind turbines, and more in particular near-field RCS computations, we have noticed that sometimes, even stabilized MoM solutions do not behave as expected. In this paper, we will give examples of some RCS computations in different scenarios. We found out that discrepancies in some RCS values are due to the choice of the meshing. Usually, standard meshers like gmsh only take into account one object. Unfortunately, to be accurate, all the positions of all objects have to be taken into account, to allow an accurate interaction between the objects. We will go deeper into the fundamentals of the relation between the accuracy and the mesh size and shape for some canonic problems of which the solution is exactly known.

This paper describes and discusses the implementation of a project-based graduate design course in telecommunications engineering. This course, which requires a combination of technical and soft skills for its completion, enables guided independent learning (GIL) and application of technical knowledge acquired from classroom learning. Its main implementation challenge is the need for instructors to define graduate-level GIL activities that are unique for the project objectives and scope. This process is required at both the system and subsystem levels. These activities must also satisfy the program learning outcomes and course outcomes (PLOs and COs). The course initiation, implementation, and management are first described from the instructor's perspective. Technical specifications and outcomes from a recently implemented project titled "A Human-Inspired Telecommunication System" is taken as a case study. Besides explaining the methodology used to evaluate both the course and the students, an empirical assessment of PLOs and COs against the associated educational activities is also presented. Results of a student exit survey, in which each instrument was mapped to specific COs, indicated that the intended course objectives had been accomplished and that there was a good level of student satisfaction.

The low frequency instability in the method of moments can be resolved by reformulating the underlying integral equations to explicitly include charge as an unknown. It turns out not to be necessary to explicitly solve for the charge, however, nor is the combined field integral equation technique always needed to derive a square matrix. Therefore, a reformulated charge and current technique has been developed. It has been implemented using a simple set of basis and testing functions, and verified both qualitatively and quantitatively checking both the charge and current distributions as well as the scattered field. These results show the method to be both stable and accurate.

the aim of this document is to study the feasibility of installing a DVB-H antenna on top of the gondola of a wind turbine. Indeed, at the moment the study was initiated, there was only information available on the influence of wind turbines on analog TV reception [1]. The speed of the blades will generate reflected/diffracted rays with Doppler and delay. With EPICS ray tracing software the electromagnetic rays arriving to the receiver antenna are computed and analyzed using Matlab. The resultant data are introduced in a DVB-H link simulator to compute the BER. Conclusions will be drawn on the effect of these interferences on the DVB-H receiver. It will be shown that only in few cases significant effects can be noticed.