Modeling the long-range wave propagation by a split-step wavelet method

International audienceA split-step wavelet method for simulating the long-range wave propagation is introduced. It is based on the fast wavelet transform. Compared to the split-step Fourier method, this method improves the computation efficiency while keeping a good accuracy. The propagation is performed iteratively by means of a pre-computed matrix containing the individual propagations of the wavelets. A fast computation method of this matrix is also presented. For the radiowave propagation in the low troposphere, a local image method is proposed to account for an impedance ground. Inhomogeneous atmospheres and irregular grounds are also considered. Finally, numerical tests of long-range propagations are performed to show the accuracy and time efficiency of this method

Comparisons of discrete and continuous propagators for the modelling of low tropospheric propagation

International audienceFor modelling the propagation of electromagnetic waves in the low troposphere, the discrete mixed Fourier method is classically used. It is based on a finite-difference approximation of the ground boundary condition. However, the propagator of the split-step Fourier method is derived from continuous equations. In this paper, we apply the finite-difference approximation to the propagation equation. A discrete operator is derived from these discrete equations. The continuous and discrete propagators are compared. The accuracy of these propagators is numerically analysed in free space and over an impedance ground. We show that the discrete propagator avoids some numerical instabilities

Probabilistic VOR error due to several scatterers — Application to wind farms

International audienceThis paper introduces a method to calculate the VOR error due to multipaths from several known scatterers within known quantiles. In such a configuration, the amplitudes of the multipaths can be numerically or analytically calculated, whereas their phases are modelled as uniformly distributed. A probabilistic formulation of the VOR error that overestimates its variance is introduced to obtain the quantiles. The method is useful to obtain probabilities of occurrence of large VOR errors for multiple configurations and in a short computation time. Examples with wind farms are presented

Antenna Gain and Link Budget for Waves Carrying Orbital Angular Momentum (OAM)

This paper addresses the RF link budget of a communication system using unusual waves carrying an orbital angular momentum (OAM) in order to clearly analyse the fundamental changes for telecommunication applications. The study is based on a typical configuration using circular array antennas to transmit and receive OAM waves. For any value of the OAM mode order, an original asymptotic formulation of the link budget is proposed in which equivalent antenna gains and free-space losses appear. The formulations are then validated with the results of a commercial electromagnetic simulation software. By this way, we also show how our formula can help to design a system capable of superimposing several channels on the same bandwidth and the same polarisation, based on the orthogonality of the OAM. Additional losses due to the use of this degree of freedom are notably clearly calculated to quantify the benefit and drawback according to the case.Comment: 33 pages, 11 figure

Methodology for Assessing the Impact of Wind Turbines on Civil Aviation Primary and Secondary Radars

International audienc

GNSS Multipath Error Model for Aircraft Surface Navigation Based on Canonical Scenarios for Class F Airports

International audienceIn this study, the GNSS multipath simulator for aircraft navigation on the airport surface from [1] is used to derive a multipath pseudo¬range error model. First the principle of this deterministic¬statistical multipath simulator is reminded. A numerical validation of the electromagnetic multipath prediction is made by establishing the channel transfer function and comparing it to the one obtained with an electromagnetic software, FEKO, using the Method of Moments. To illustrate the outputs of such simulator, a comparison to measurements performed at ENAC is given. Then, after reminding the multipath pseudo¬range error model that was established in [2], a multipath pseudo¬range error model is adapted to ICAO code F airport layouts [3]. This model is based on the identification of canonical scenarios representing the taxi operation phase. The power spectral density of the multipath pseudo¬range errors is over¬bounded by a first order Gauss¬Markov spectral density. An example of application for the taxi on stand taxilane sub¬phase is proposed. In this example, the over¬bounding distribution fits quite well the power spectral density of the estimated multipath pseudo¬range errors

A Stastistical Model for Assessing the Impact of Wind Turbines on Conventionnal VOR

International audienc

A Dynamic VOR Receiver Model for Estimating the Bearing Error in the Presence of Wind Turbines

International audienceThis work introduces a dynamic VOR receiver model for estimating the bearing error in the presence of wind turbines. The receiver processes time series generated by an electromagnetic simulation tool that takes into account the multipaths. This global model can reproduce the response of a VOR receiver on a realistic aircraft trajectory. The receiver is tested in a dynamic scenario where the multipaths change rapidly with time

Analysis of an IQ Receiver Model by Means of Laboratory Measurements for Conventional VOR

International audienc

Single-fed circularly polarized dielectric resonator antenna using a uniaxial anisotropic material

A Dielectric Resonator Antenna operating in circular polarization is presented. The proposed antenna is formed by a uniaxial anisotropic dielectric and a ground plane. The optimization of the permittivity tensor and antenna dimensions is performed both theoretically and numerically using an Eigen mode analysis in Ansys HFSS. A good agreement is obtained for the resonant frequencies and quality factors of the different modes. The uniaxial anisotropic DRA radiates two degenerate orthogonal modes, TE111x and TE111y, with equal amplitudes and 90° phase difference in order to achieve circular polarization. An impedance bandwidth of 9.8% is accomplished and a broadside radiation pattern with left-hand circular polarization (LHCP) is achieved in simulation. Furthermore, an Axial Ratio (AR) of 0.06 dB at 2.45 GHz and a 3-dB AR bandwidth of 2.04% are obtained. The maximum simulated directivity is equal to 6.56 dBi