TM Electromagnetic Scattering from PEC Polygonal Cross-Section Cylinders: A New Analytical Approach for the Efficient Evaluation of Improper Integrals Involving Oscillating and Slowly Decaying Functions

The analysis of the TM electromagnetic scattering from perfectly electrically conducting polygonal cross-section cylinders is successfully carried out by means of an electric field integral equation formulation in the spectral domain and the method of analytical preconditioning which leads to a matrix equation at which Fredholm's theory can be applied. Hence, the convergence of the discretization scheme is guaranteed. Unfortunately, the matrix coefficients are improper integrals involving oscillating and, in the worst cases, slowly decaying functions. Moreover, the classical analytical asymptotic acceleration technique leads to faster decaying integrands without overcoming the most important problem of their oscillating nature. Thus, the computation time rapidly increases as higher is the accuracy required for the solution. The aim of this paper is to show a new analytical technique for the efficient evaluation of such kind of integrals even when high accuracy is required for the solution

Experimental and numerical evaluations on palm microwave heating for Red Palm Weevil pest control

The invasive Red Palm Weevil is the major pest of palms. Several control methods have been applied, however concern is raised regarding the treatments that can cause significant environmental pollution. In this context the use of microwaves is particularly attractive. Microwave heating applications are increasingly proposed in the management of a wide range of agricultural and wood pests, exploiting the thermal death induced in the insects that have a thermal tolerance lower than that of the host matrices. This paper describes research aiming to combat the Red Palm pest using microwave heating systems. An electromagnetic-thermal model was developed to better control the temperature profile inside the palm tissues. In this process both electromagnetic and thermal parameters are involved, the latter being particularly critical depending on plant physiology. Their evaluation was carried out by fitting experimental data and the thermal model with few free parameters. The results obtained by the simplified model well match with both that of a commercial software 3D model and measurements on treated Phoenix canariensis palms with a ring microwave applicator. This work confirms that microwave heating is a promising, eco-compatible solution to fight the spread of weevil

The Information Carried by Scattered Waves: Near-Field and Nonasymptotic Regimes

The number of spatial degrees of freedom of the field radiated in a two-dimensional setting by a time-harmonic, arbitrary square-integrable current density and in the presence of a random distribution of scattering elements is determined. It is shown that the active power associated to the $k$ th singular value of the near field in the presence of scatterers external to the cut presents a heavy tail decay as a function of its index, rather than the usual exponential attenuation occurring beyond a critical index term observed in free space. This near-field information gain due to scattering was recently anticipated by Janaswamy using a stochastic source model, it is extended here to arbitrary sources, and it is shown to disappear in the limit of large radiating systems. It is also shown that the same information gain and asymptotic cut-off occurs for the singular values of the field radiating in free space. Collectively, these results show that while the presence of scatterers external to the cut can increase the number of channels that can be exploited for communication by the active power in the near field, they do not change the number of channels associated to the field, nor the asymptotic behavior of the number of degrees of freedom

A Theoretical and Experimental Investigation on the Measurement of the Electromagnetic Field Level Radiated by 5G Base Stations

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A New Paradigm in 5G Maximum Power Extrapolation for Human Exposure Assessment: Forcing gNB Traffic Toward the Measurement Equipment

5G base stations usually use different beams to transmit broadcast and user data. Moreover the broadcast beam is always “on air”, whilst the traffic beam is not. This represents a problem in Maximum Power Extrapolation (MPE) procedures for exposure assessment. In fact, currently adopted measurement approaches are based on the mere observation of phenomena. Recently, a different approach for MPE has been proposed by Adda et al., 2020, forcing the traffic toward the measuring position by means of a dedicated User Equipment (UE). Consequently, the measurer loses the “passive” role assumed in the approach usually adopted, and acquires an active role forcing the system under test to assume the most suitable configuration. The use of beam-forcing UEs opens new exciting possibilities, since it makes it possible to take advantage of the UE-specific signals for the estimation for the MPE procedure. The aim of this paper is to explore the potential offered by UE-specific data structures within the MPE considering a real case regarding data acquired on a currently operative 5G base station

Methodology Based on Vector and Scalar Measurement of Traffic Channel Power Levels to Assess Maximum Exposure to Electromagnetic Radiation Generated by 5G NR Systems

Maximum-Power Extrapolation (MPE) for mobile telecommunication sources follows an established paradigm based on the identification and measurement of a channel that acts as a power reference. Prior to the 5G era, the role of reference channel has been played by always-on broadcast signals since they had the great advantage of being always transmitted at the maximum power level allowed for a generic signal channel. However, the beamforming implemented by 5G sources obliges us to rethink this approach. In fact, with beamforming the 5G source can transmit data traffic streams through a beam characterized by a much higher gain than the broadcast one. This implies that the detected power for traffic beams could be much higher than the corresponding power of broadcast beams. In this paper, a novel approach for 5G MPE procedure is presented, where the direct measurement of the received power of a traffic beam is used to assess the maximum exposure generated by a 5G system. An innovative specific experimental setup is also proposed, with the use of a User Equipment (UE) with the aim of forcing the traffic beam toward the measurement positions. In this way, it is possible to directly measure the power of each Resource Element (RE) transmitted by the traffic beam. As opposed to other MPE proposals for 5G, the discussed technique does not require any correction of the measured data since it relies only on the traffic beam pointing toward the measurement position, simplifying the overall MPE procedure and thus reducing the uncertainty of the MPE estimated field strength

Analytically Regularized Evaluation of the Coupling of Planar Concentric Conducting Rings

In this paper, an accurate and efficient method for the analysis of coupled perfectly conducting annular rings is presented. The problem is first formulated as a couple of Integral Equation (IEs) in the Vector Hankel Transform (VHT) domain, considered as unknowns in the cylindrical harmonics of the unknown surface current density. As a second step, Galerkin’s method is applied with suitable expansion functions. The selected functions have two main properties: they reconstruct the expected physical behavior of the nth cylindrical harmonic at the edges of the annular rings, and their VHT transform is analytical and can be expressed in closed-form. Consequently, the method is effective and the problem is regularized, as testified by the truncation error. Comparisons with the commercial software CST Microwave Studio have been carried out and are presented to validate the method