X-ray fluorescence analysis of yellow pigments in altarpieces by Valencian artists of the XV and XVI centuries

Abstract XRF analysis has allowed a quick and precise detection and identification of the inorganic elements that compose the yellow pigments in altarpieces of the XV and XVI centuries painted by the Valencian artists Miguel Alcaniz, Vicente Macip, Juan de Juanes, Hernando Yanez de la Almedina and Hernando Llanos. The analyses have been carried out with an XRF portable system that consists of a tube of X-rays and detectors of Si(Li) and cadmium zinc telluride. This system has enabled a non-aggressive and non-destructive analysis of many pieces at the Museo de Bellas Artes of Valencia (Spain). Among the yellow pigments we have identified a pigment composed by lead and tin oxides named lead–t…

Dynamics of thermally induced optical nonlinearity in GaSe thin slabs

A study of the nonlinear effects shown by thin slabs of GaSe metaled with Au is presented.

Extremely low frequency band station for natural electromagnetic noise measurement

A new permanent ELF measurement station has been deployed in Sierra Nevada, Spain. It is composed of two magnetometers, oriented NS and EW, respectively. At 10 Hz, their sensitivity is 19 μV/pT and the signal-to-noise ratio (SNR) is 28 dB for a time-varying signal of 1 pT, the expected field amplitude in Sierra Nevada. The station operates for frequencies below 24 Hz. The magnetometers, together with their corresponding electronics, have been specifically designed to achieve such an SNR for small signals. They are based on high-resolution search coils with ferromagnetic core and 106 turns, operating in limited geometry configuration. Different system noise sources are considered, and a stud…

Numerical analysis of thermally induced optical nonlinearity in GaSe layered crystal

A numerical approach to studying thermally induced optical nonlinearity in semiconductors is presented. A transient finite difference algorithm is applied to solve the thermal diffusion equation coupled with the nonlinear absorbance-transmittance of Au/GaSe/Au samples with an applied electric field. The presented analysis can deal with any arbitrary axisymmetric dependence of the input power over the sample and external electric field, and provides information about the steady state and transitory effects in the transmittance.

Transmission line meshes for computational simulation of electromagnetic modes in the Earth's atmosphere

PurposeTwo transmission line meshes to simulate electromagnetic waves in the Earth's atmosphere are developed, one with the link transmission lines connected in parallel and the other with connections in series.Design/methodology/approachThe equations describing propagation of waves through these parallel or series meshes are equivalent to the Maxwell equations for TEr or TMr modes in a spherical cavity with lossy dielectric material between the external conducting surfaces, respectively.FindingsThe transmission line meshes are used for a numerical study of the natural electromagnetic noise due to lightning discharges in the Earth‐ionosphere cavity.Originality/valueThe numerical algorithm f…

Assessment of Agricultural Options Available for Saving Orange Cultivation in Ribera Baixa (Valencia, Spain)

Orange cropping has been in practice in Ribera Baixa (Valencia, Spain) for several centuries. During the past decade, orange cropping has been under severe economic stress arising from increasing competition from less-costly foreign imports. Consequently, farm-gate prices are depressed, under the regime of fixed percentage distribution of retail pricing. Orange groves are being abandoned in many instances. A practicable and sustainable solution to this persistent economic problem would require a re-structuring of the marketing system to facilitate the sales of organic products and introduction of organic growing practices for oranges as well as secondary organic tree crops.

Calculation of the characteristic impedance of microstrips using a full-wave 2-D FDTD scheme

The frequency dependence of the characteristic impedance of microstrip lines has been investigated by many authors using 3D-FDTD formulations. In the present letter, a two-dimensional FDTD scheme is used to calculate both the propagation constant and the characteristic impedance of the fundamental quasi-TEM mode in a microstrip which, in fact, is a hybrid mode. Because of the substantial reduction of computer resources required for the calculations, this method can be used as a design tool. © 1997 John Wiley & Sons, Inc. Microwave Opt Technol Lett 16: 58–60, 1997.

A numerical study of atmospheric signals in the Earth-ionosphere electromagnetic cavity with the Transmission Line Matrix method

[1] The effect of the Earth-ionosphere electromagnetic cavity on the spectrum of an atmospheric signal generated by a broadband electrical current source is analyzed numerically by means of the Transmission Line Matrix (TLM) method. Two new TLM meshes are developed, one with transmission lines connected in parallel and the other with connections in series. The equations describing propagation through these parallel or series meshes are equivalent to the Maxwell equations for TEr or TMr modes in the spherical Earth-ionosphere cavity, respectively. The numerical algorithm obtains Schumann resonance frequencies very close to the experimental ones, confirming that this methodology is a valid nu…

Electromagnetic Scattering by a Strip Grating with Plane-Wave Three-Dimensional Oblique Incidence by Means of Decomposition into E-Type and H-Type Modes

A numerical algorithm to analyze the plane-wave three-dimensional oblique incidence on a strip grating is presented. Electromagnetic field is decomposed into vector Floquet harmonics of the E-type and H-type modes. To impose boundary conditions on the incident, reflected and transmitted waves, two integral equations of Fredholm of first kind are obtained. These equations are solved numerically with the standard Galerkin procedure, and the convergence of the algorithm is examined numerically. Since the superficial current near the edges of a conducting strip have been taken into account, the computational algorithm shows a fast convergence. Results are compared with other numerical results a…

Solar storm effects during Saint Patrick's Days in 2013 and 2015 on the Schumann resonances measured by the ELF station at Sierra Nevada (Spain)

Full-wave FDTD design and analysis of wideband microstrip-to-waveguide transitions

Wideband transitions are designed and analysed by using two different approaches of the finite-difference time-domain (FDTD) method, in combination with the theory of nonuniform transmission lines. These transitions consist of a ridged waveguide-based taper between a shielded microstrip and a standard X-band rectangular waveguide. In the first step, a full-wave 2D-FDTD scheme is used to calculate the dispersion characteristics, as well as the geometry dependence of the impedance in the double ridged waveguide. Once these design curves have been obtained, the stepped transmission line transformer theory is used to design the tapers. In a former step, the nonuniform 3D-FDTD technique is appli…

TLM Nodes: A New Look at an Old Problem

In this paper, an alternative perspective on the transmission line modeling (TLM) method concepts to unify previous work is presented. The procedure begins by discretizing Maxwell’s equations and proposing TLM equivalent models. Node voltage and mesh current definitions are provided in terms of link line contributions, compatible with stub currents and voltages. They allow obtaining an expression that relates incident and reflected pulses with no other condition required. With this unified approach, modeling of other situations is straightforward. 2-D cases, source implementation, and anisotropic media are described and numerically tested.

A new bi-faced log periodic printed antenna

In this paper, a new design of a broadband planar printed antenna based on the academic log periodic antenna is presented. The antenna consists of a series of printed dipoles, distributed on both faces of the substrate. Some configurations are explored, with a different number of printed dipoles. These are designed, simulated, fabricated, and measured. The calculated and measured return losses and radiation patterns are presented. The utility of the proposed antenna associated with its frequency bandwidth is better than 80%. The measured absolute gain is 6.5 dBi, and the front-to-back ratio is around 8 dB. The presented antenna should find wide applications in wireless communication systems…

Test of the generation of High-Frequency Gravitational Waves by irradiating a dielectric film in a resonant cavity

A recent proposal for generating High Frequency Gravitational Waves (HFGW) is based on the conversion of electromagnetic waves into gravitational waves by irradiating a dielectric film in the extreme conditions of a high vacuum and a strong magnetic field. These HFGWs can be tested using an electron paramagnetic resonant spectrometer (EPRS). This device contains all the necessary ingredients: a vacuum chamber, microwave generator, a strong magnetic field, and a resonant cavity where the substance to be analysed is introduced. The EPR spectrum of a very small paramagnetic core in a substance is the graph of the absorption of the paramagnetic core as a function of the strong magnetic field B.…

Practical Considerations in the Implementation of Collaborative Beamforming on Wireless Sensor Networks

Wireless Sensor Networks (WSNs) are composed of spatially distributed autonomous sensor devices, named motes. These motes have their own power supply, processing unit, sensors and wireless communications However with many constraints, such as limited energy, bandwidth and computational capabilities. In these networks, at least one mote called a sink, acts as a gateway to connect with other networks. These sensor networks run monitoring applications and then the data gathered by these motes needs to be retrieved by the sink. When this sink is located in the far field, there have been many proposals in the literature based on Collaborative Beamforming (CB), also known as Distributed or Cooper…

Transmission-line model to analyze a multistage polarizer rotator

A simple transmission-line model to design a broadband system consisting of a multilayered polarization rotator that rotates the polarization plane of a linearly polarized electromagnetic wave is presented. A simulation program that permits the design of the rotator parameters was implemented, and a prototype was designed, manufactured, and tested. Comparisons between the theoretical results and measurements are given, and a good correspondence is found.

An analysis of VLF electric field spectra measured in Titan's atmosphere by the Huygens probe

[1] A numerical simulation of Titan's electromagnetic cavity in the VLF band is carried out using the Transmission Line Matrix (TLM) method, with the aim of assessing the VLF electric field spectra sent by the Huygens probe. In an Earth-like model, successive peaks would be expected in the spectra, associated with multiple reflections of the electromagnetic wave on the external surfaces of Titan's electromagnetic cavity, formed by the ionosphere and a conductive ground or underground surface. However, owing to high losses conferred by the electrical conductivity to Titan's atmosphere, the direct numerical and experimental spectra are decreasing functions of the frequency without resonances …

Analysis of the finite difference time domain technique to solve the Schrödinger equation for quantum devices

An extension of the finite difference time domain is applied to solve the Schrödinger equation. A systematic analysis of stability and convergence of this technique is carried out in this article. The numerical scheme used to solve the Schrödinger equation differs from the scheme found in electromagnetics. Also, the unit cell employed to model quantum devices is different from the Yee cell used by the electrical engineering community. A bound for the time step is derived to ensure stability. Several numerical experiments in quantum structures demonstrate the accuracy of a second order, comparable to the analysis of electromagnetic devices with the Yee cell. a!Electronic mail: Antonio.Sorian…

Efficient FDTD analysis of discontinuities in a square coaxial waveguide

FDTD analysis of E-sectoral horn antennas for broad-band applications

The finite-difference time-domain (FDTD) method is applied to study the performance of E-plane sectoral horn antennas designed for broad-band applications. These antennas (proposed for 6-18 GHz phased arrays) have a large bandwidth, and they are easily array integrated. These antennas have a highly complicated geometry that is modeled using a polygonal approximation in the curved boundaries. Perfect matched layers (PMLs) combined with first-order absorbing boundaries are employed to simulate the free-space environment in the FDTD mesh.

Low intensity magnetic field influences short-term memory: A study in a group of healthy students

This study analyzes if an external magnetic stimulus (2 kHz and approximately 0.1 μT applied near frontal cortex) influences working memory, perception, binary decision, motor execution, and sustained attention in humans. A magnetic stimulus and a sham stimulus were applied to both sides of the head (frontal cortex close to temporal-parietal area) in young and healthy male test subjects (n = 65) while performing Sternberg's memory scanning task. There was a significant change in reaction time. Times recorded for perception, sustained attention, and motor execution were lower in exposed subjects (P < 0.01). However, time employed in binary decision increased for subjects exposed to magnetic …

A circular mesh scheme for the non-orthogonal finite difference time domain method

Beam forming networks (BFN) are an important component of a complex satellite antenna system because they are used to provide accurate amplitude and phase excitation to the elements of the feed network. The need for handling high power and the need for a high degree of integrability, often leads one to choose square coaxial metal lines for constructing BFNs. BFNs usually require variable power dividers such as the rat-race (or ring) couplers with constant or variable divider ratios in order to deliver a prescribed amount of power to a certain element of an antenna array to steer the beam in a desired direction. However, modeling of such circular structures in square coaxial form is not an e…

Evidence of electrical activity on Titan drawn from the Schumann resonances sent by Huygens probe

Abstract A procedure is shown for extracting weak resonances from the responses of electromagnetic systems excited by electric discharges. The procedure, based on analysis of the late-time system response, is first checked using an analytical function and later with the data for the electric field generated by the computational simulation of Titan's atmosphere using the Transmission Line Matrix (TLM) method. Finally, the low frequency spectrum of the natural electric field in Titan's atmosphere sent by the mutual impedance sensor (MIP) included in the Huygens probe is analyzed employing this technique. The MIP sensor was initially designed to measure the horizontal component of the electric…

Design & Optimization of Large Cylindrical Radomes with Subcell and Non-Orthogonal FDTD Meshes Combined with Genetic Algorithms

The word radome is a contraction of radar and dome. The function of radomes is to protect antennas from atmospheric agents. Radomes are closed structures that protect the antennas from environmental factors such as wind, rain, ice, sand, and ultraviolet rays, among others. The radomes are passive structures that introduce return losses, and whose proper design would relax the requirement of complex front-end elements such as amplifiers. The radome consists mostly in a thin dielectric curved shape cover and sometimes needs to be tuned using metal inserts to cancel the capacitive performance of the dielectric. Radomes are in the near field region of the antennas and a full wave analysis of th…

Rigorous analysis of three-dimensional beam transmission through a dielectric slab

The plane-wave-spectrum technique is applied to study the transmission of a three-dimensional beam through a dielectric slab. The electromagnetic beam radiated from an aperture antenna is represented by an angular spectrum of plane waves. The use of three different co-ordinate systems using rectangular co-ordinates allows a rigorous formulation to be obtained. The near field transmitted through a dielectric slab is obtained and compared with measurements.

Design and Study of a Wide-Band Printed Circuit Board Near-Field Probe

Magnetic near-field probes (NFP) represent a suitable tool to measure the magnetic field level from a small electromagnetic interference (EMI) source. This kind of antenna is useful as a magnetic field probe for pre-compliance EMC measurements or debugging tasks since the user can scan a printed circuit board (PCB) looking for locations with strong magnetic fields. When a strong H-field point is found, the designer should check the PCB layout and components placement in that area to detect if this could result in an EMI source. This contribution focuses on analyzing the performance of an easy to build and low-cost H-field NFP designed and manufactured using a standard PCB stack-up. Thereby,…

Rebuttal to “Comment on “Evidence of electrical activity on Titan drawn from the Schumann resonances sent by Huygens probe” by J.A. Morente, J.A. Portí, A. Salinas, and E.A. Navarro [2008, Icarus, 195, 802–811]”

Abstract Hamelin et al. criticize some conclusions of our paper [Morente, J.A., Porti, J.A., Salinas, A., Navarro, E.A., 2008. Icarus 195, 802–811]. This rebuttal is our response to their criticism. In our view, their comments are contradictory and not based on scientific argument. Our paper presents a comprehensible methodology for extracting weak resonances from the late-time response of systems with high losses and our conclusions are derived from and supported by this methodology, which was first checked using an analytical function and later with the data from a numerical simulation of Titan’s atmosphere. Conversely, the Comment of Hamelin et al. does not contain any mathematical proof…

The reflection coefficient of a flared microstrip line radiating in an infinite parallel-plate waveguide

In this article the reflection coefficient of a tapered microstrip line radiating in an infinite parallel-plate conducting waveguide is calculated. The reflection coefficient at the feed line is evaluated by using the aperture admittance of the horn and the scattering matrix of the continuous taper. The theoretical behavior of the aperture admittance is shown and the reflection coefficient of a microstrip horn radiating in the parallel-plate region of a bootlace lens is measured in order to verify the model. © 1993 John Wiley & sons, Inc.

A finite difference time domain model for the Titan ionosphere Schumann resonances

[1] This paper presents a numerical approach to model the electrical properties of Titan's atmosphere. The finite difference time domain technique is applied to model the atmosphere of Saturn's satellite in order to determine Schumann resonant frequencies and electromagnetic field distributions at the extremely low frequency range. Spherical coordinates are employed, and periodic boundary conditions are implemented in order to exploit the symmetry in rotation of the celestial body. Results are compared with a previous model using the transmission line matrix method up to 180 km altitude. For the first time a numerical FDTD model up to 800 km altitude is carried out, and we report lower freq…

Kinetic Interaction of Cold and Hot Protons With an Oblique EMIC Wave Near the Dayside Reconnecting Magnetopause

STR acknowledges support from the ISSI international team Cold plasma of ionospheric origin in the Earth's magnetosphere and of the Ministry of Economy and Competitiveness (MINECO) of Spain (grant FIS2017-90102-R). Research at IRAP was supported by CNRS, CNES and the University of Toulouse. JHL and DLT acknowledge support from NASA Grant 80NSSC18K1378. RED was supported by NASA grants 80NSSC19K070 and 80NSSC19K0254. MA was supported by SNSA Grant 56/18. SKV and RCA acknowledge support from NASA Grant 80NSSC19K0270. Work performed by MMS team members is supported by NASA contract NNG04EB99C.

Transmission properties at microwave frequencies of two-dimensional metallic lattices

The transmission properties of different metallic photonic lattices (square and rectangular) have been experimentally studied. A numerical algorithm based on time domain finite differences has been used for simulating these photonic structures. The introduction of defects in the two-dimensional metallic lattice modifies its transmission spectrum. If metal rods are eliminated from (or added to) the lattice, extremely narrow peaks are observed at some particular frequencies below (or above) the band pass edge. Vicente.Such@uv.es ; Enrique.Navarro@uv.es

The Microwave Syndrome: A Preliminary Study in Spain

A health survey was carried out in Murcia, Spain, in the vicinity of a Cellular Phone Base Station working in DCS‐1800 MHz. This survey contained health items related to “microwave sickness” or “RF syndrome.” The microwave power density was measured at the respondents' homes. Statistical analysis showed significant correlation between the declared severity of the symptoms and the measured power density. The separation of respondents into two different exposure groups also showed an increase of the declared severity in the group with the higher exposure.

A New Approach to the Modeling of Anisotropic Media with the Transmission Line Matrix Method

A reformulation of the Transmission Line Matrix (TLM) method is presented to model non-dispersive anisotropic media. Two TLM-based solutions to solve this problem can already be found in the literature, each one with an interesting feature. One can be considered a more conceptual approach, close to the TLM fundamentals, which identifies each TLM in Maxwell’s equations with a specific line. But this simplicity is achieved at the expense of an increase in the memory storage requirements of a general situation. The second existing solution is a more powerful and general formulation that avoids this increase in memory storage. However, it is based on signal processing techniques and considerabl…

FDTD characterization of evanescent modes-multimode analysis of waveguide discontinuities

In this paper, a finite-difference time-domain numerical dispersion relation for evanescent waves is derived, and its impact on the modeling accuracy is studied. The numerical evanescent constant is found to differ from the analytical one. As a result, a correction must be used to compute discontinuity parameters. This influences the reference plane chosen for the analysis of propagating modes. Moreover, on calculating multimode transmission and reflection coefficients, the dispersion for evanescent higher order modes is determinant. The dispersive relation is derived, discussed, and used to correct the evanescent constants for the multimode analysis of a waveguide discontinuity.

Coaxial Slot Antenna Design for Microwave Hyperthermia using Finite- Difference Time-Domain and Finite Element Method

Hyperthermia also called thermal therapy or thermotherapy is a type of cancer treatment in which body tissue is exposed to high temperatures. Research has shown that high temperatures can damage and kill cancer cells, usually with minimal injury to normal tissues. Otherwise, ablation or high temperature hyperthermia, including lasers and the use of radiofrequency, microwaves, and high-intensity focused ultrasound, are gaining attention as an alternative to standard sur- gical therapies. The electromagnetic microwave irradiation applied to the tumor tissue causes water molecules to vibrate and rotate, resulting in tissue heating and subsequently cell death via thermal-induced protein denatur…

Reply to comment by R. Grard et al. on “An analysis of VLF electric field spectra measured in Titan's atmosphere by the Huygens probe”

Subjective symptoms related to GSM radiation from mobile phone base stations : a cross-sectional study

Objectives: We performed a reanalysis of the data from Navarro et al., 2003, in which health symptoms related to microwave exposure from mobile phone base stations (BS) were explored, including data obtained in a retrospective inquiry about fear of exposure from BS. Design: Cross-sectional study. Setting: La Ñora (Murcia), Spain. Participants: Participants with known illness in 2003 were subsequently disregarded: 88 participants instead of 101 (in 2003) were analysed. Since weather circumstances can influence exposure, we restricted data to measurements made under similar weather conditions. Outcomes and methods: A statistical method indifferent to the assumption of normality was employed: …

Radioactivity measurements on migrating birds (Turdus philomelos) captured in the Comunidad Valenciana (Spain)

The radionuclides 137Cs, 134Cs and 90Sr have been measured in edible tissues and bones of migratory birds (song-thrushes, Turdus philomelos) from central and northern Europe and captured in the Comunidad Valenciana, Spain in the 1994 autumn–winter season. Eight years after the Chernobyl accident, extensive agricultural lands in Europe are still contaminated and this study shows that there was a transfer of radioactive isotopes to the captured migratory song-thrushes. The whole-body dose commitment to humans consuming these birds is estimated.

Numerical analysis of ionosphere disturbances and Schumann mode splitting in the Earth-ionosphere cavity

[1] The variability of ionosphere properties plays an important role in the Schumann resonances (SR), amplitudes, frequencies, and Q factor. Therefore, as atmosphere ionization is related to solar activity, SR could be devised as a source of indirect parameters that locally from the surface of the Earth could provide space weather information. A proper understanding of this link to SR parameters can be obtained through finite difference time domain (FDTD) simulations, specifically with the numerically obtained modes and frequencies that relate frequency shifts to the day-night asymmetry and polar inhomogeneities. Day-Night asymmetry is observed to have a minor influence in SR; however, larg…

FDTD signal extrapolation using a finite impulse response neural network model

Applications of the X-ray fluorescence analysis to the cultural patrimony of the Comunidad Valenciana (Spain): Painting, metal and paper

We present examples of the application of the X-ray fluorescence (XRF) to the study of the artistic and cultural patrimony of the Comunidad Valenciana in the following areas: a) Valencian paintings of the XV and XVI centuries; b) silver ornaments coming from Iberian towns (s. III b.C.); c) ink and paper samples in manuscripts and engravings of the XVII and XIX centuries. The non destructive analyses are carried out “in situ” using a XRF system that consists of a tube of X-rays of 50 kV and 1 mA, and a detector of Si(Li) with an energy resolution 140 eV (FWHM at 5.9 keV).

Microalgal oil production for use in rice farms in Albufera (València) region

In the Albufera (Valencia) region of Spain, rice has been farmed for nearly 500 years. Post-harvest flooding of rice fields has become an integral element of wetland refuge for migratory birds. The steady rise in the cost of purchased inputs is causing considerable economic stress to the viability of rice farming in this region. In 2011, it has been estimated the cost of purchased diesel accounted for about 15% of the gross revenue from grain sales. Setting aside about 1.6% of the 14,350-hectare paddy fields for the dedicated yearround cultivation of oleaginous microalgae appears to be sufficient for the entire annual need of diesel fuel. The isolated crude microalgal oil could be used dire…

A neural network-based approach to determine FDTD eigenfunctions in quantum devices

This article combines a Neural Network (NN) algorithm with the Finite Difference Time Domain (FDTD) technique to estimate the eigenfunctions in quantum devices. A NN based on the Least Mean Squares (LMS) algorithm is combined with the FDTD technique to provide a first approach to the confined states in quantum wires. The proposed technique is in good agreement with analytical results and is more efficient than FDTD combined with the Fourier Transform. This technique is used to cal- culate a numerical approximation to the eigenfunctions associated to quan- tum wire potentials. The performance and convergence of the proposed technique are also presented in this article. © 2009 Wiley Periodica…

Recent evolution of the multi-isotopic radioactive content in ice of Livingston Island, Antarctica.

The temporal arrangement of the ice layers that are produced in ecosystems with perpetual snows form situations that greatly favour the study of the temporal evolution of the radioactive fallout that occurs in the said zones, whether this fallout is natural or artificial in origin. This allows one to investigate the causes of the fallout and the mechanisms transporting the radionuclides involved from their source point to the study zone, as well as their subsequent behaviour in that zone. There are special difficulties involved in this type of study in Antarctica. Some are of a general character deriving from the conditions of extreme climate and isolation which complicate the processes of …

Adapting available finite element structural programs to solve three-dimensional high frequency electromagnetic problems

The adaptation of available structural mechanics software to solve microwave problems is possible by the analogy between the differential equations. A brief review of the analogy between transverse or shear waves in elasticity and electromagnetic waves is presented, followed by a more detailed discussion of the adaptation of a program to obtain the resonant frequencies of a rectangular resonant cavity, doing a three-dimensional analysis. The geometry of the electric field is also obtained for the resonant modes.

A numerical study of the Schumann resonances in Mars with the FDTD method

[1] Natural electromagnetic waves generated near the surface by electrostatic discharges in dust storms (dust devils) or by geological activity could be trapped in the resonant cavity formed by the surface and lower ionosphere of Mars, as it occurs on Earth giving rise to Schumann resonances. The finite difference time-domain technique (FDTD) is applied to model the atmosphere of Mars in order to determine Schumann resonant frequencies, and natural electromagnetic fields at the extremely low frequency range (ELF). A numerical tool is provided to analyze the electrical conductivity profile of the Martian atmosphere, with the aim of obtaining Schumann resonance frequencies and their dependenc…