Magdalena S. Palma

• PhD
• University Carlos III de Madrid

This chapter presents a nonparametric method for the application of the principle of analytic continuation to interpolate/extrapolate system responses resulting in reduced computations. The Hilbert transform can also be used to speed up the spectral analysis of nonuniformly spaced data samples. One of the properties of the periodogram approach is t...

Chebyshev polynomials are used to extract from the data collected under non‐anechoic environment a radiation pattern for the same antenna radiating in free space conditions. The Cauchy method based on Gegenbauer polynomials is presented for antenna near‐field extrapolation and the far‐field estimation. Some numerical results are given to demonstrat...

The source reconstruction method (SRM) is a technique developed for antenna diagnostics and for carrying out near‐field to far‐field transformation. This chapter presents two different methods: one that deals with the equivalent magnetic current and the second that deals with the equivalent electric current. It also presents the examples to illustr...

In the mathematical field of numerical analysis, model order reduction is the key to processing measured data. This chapter outlines philosophy of model order reduction along with the concepts of total least squares and singular value decomposition. It introduces a critical component in solving a total least squares problem called the singular valu...

This chapter presents the concept of the Cauchy method for the interpolation and extrapolation of data. The Cauchy method is to interpolate and extrapolate the data from calculating coefficients simultaneously of the numerator and denominator polynomials which are used to approximate the data by a ratio of two polynomials. The usefulness of the Cau...

Antenna pattern measurements are usually carried out in an anechoic chamber. This chapter illustrates a deconvolution methodology which allows the antenna measurement under a non‐anechoic test environment and retrieves the free space radiation pattern of an antenna through this measured data; thus allowing for easier and more affordable antenna mea...

This chapter presents two methods for spherical near‐field to far‐field transformation. The first methodology presents an exact explicit analytical formulation for transforming near‐field data generated over a spherical surface to the far field radiation pattern. The second method presents the equivalent source formulation that was described earlie...

A fast and accurate method is presented for computing far‐field antenna patterns from planar near‐field measurements. The planar near‐field data can be sampled either using a single moving dipole probe or using an array of dipole probes. Near‐field to far‐field transformation for planar scanning may be efficiently performed under certain conditions...

This chapter presents the matrix pencil method (MPM) which is a methodology to approximate a given data set by a sum of complex exponentials. The MPM approach is computationally very efficient and quite robust to noise in the data. The MPM has been successfully applied to high‐resolution de‐embedding procedures using band‐limited data prevalent in...

This chapter presents two deconvolution techniques to illustrate how the ill‐posed deconvolution problem has been regularized. The two techniques presented have the built in self‐regularizing schemes. The first method is based on solving the ill‐posed deconvolution problem by the iterative conjugate gradient method. The second method uses the metho...

In the solution of frequency-and time-domain integral equations, the singularity cancellation transformations are well-known for the treatments of the singular integrals involving the Green’s functions and their gradients. The cancellation transformations for strongly near-singular integrals become inaccurate and inefficient for an extremely deform...

Recounts the career and contributions of Tapan Sarkar.

The objective of this article is to illustrate the concepts of multiplc-input-multiple--oulput (MIMO) systems from an electromagnetic perspective and illustrated using computational techniques. The various conceptual evolutionary steps of MIMO are described. This methodology went through various distinct disjoint philosophies to satisfy its critics...

The objective of this paper is to illustrate that computational electromagnetics can be used very effectively to improve the accuracy and efficiency of antenna pattern measurements. This is accomplished by moving a single probe over the measurement plane to generate enhanced accuracy in planar near field to far field transformation than over the cl...

In this paper, an adaptive processing is carried out simultaneously at multiple frequencies using the same antenna array consisting of non-uniformly spaced dissimilar antenna elements. The antenna array may not be deployed in free space but may be located over an imperfect ground plane. First to correct for the various electromagnetic effects affec...

In this article, we describe the notion of a cloak achieved by employing the usual composite dielectrics surrounding a metal cube, a concept that was first presented by Hwang and Chin [1]. Here, we use an optimization procedure to improve on their results and obtain a three-dimensional composite dielectric structure that can achieve a better broadb...

This presentation focuses on the design and characterization process of an active array demonstrator for the mid-frequency range (i.e., 300 MHz-1000 MHz) of the future Square Kilometre Array (SKA) radio telescope. This demonstrator, called FIDA3 (FG-IGN: Fundación General Instituto Geográfico Nacional — Differential Active Antenna Array), is part o...

Recounts the career and contributions of Professor Kenneth Kwai-Hsiang Mei.

GREMA stands for Radiofrequency, Electromagnetics, Microwaves and Antennas Research Group. GREMA -research focus in several electromagnetic fields, as for example, numerical methods with a wide coverage of techniques going from rigorous methods such as the Finite Element Method (FEM) and Method of Moments (MoM) to asymptotic high frequency techniqu...

One of the objectives of this paper is to outline the differences between the internal and external resonances of an electromagnetic structure. At an internal resonance of an object there is a component of the resonant current on the structure which is real and that current does not radiate nor does it couple to the incident field. The external res...

This review paper is a sequel to an earlier paper [1] dealing with parametric methods in the context of the principle of analytic continuation and provided its relationship to reduced rank modelling using the total least squares based singular value decomposition methodology. The problem with a parametric method is that the quality of the solution...

In this article, we provide a brief history of the evolution of radar across the various regions where the technology's development occurred, often simultaneously and independently. (Note that the original term RADAR, representing "RAdio Detection And Ranging," was devised by the U.S. Navy in 1940.) We cover in detail the years from the late 19th c...

The far field of an antenna is generally considered to be the region where the outgoing wavefront is planar and the antenna radiation pattern has a polar variation and is independent of the distance from the antenna. Hence, to generate a local plane wave in the far field, the radial component of the electric field must be negligible compared to the...

Current research on wireless radio frequency (RF) systems often makes unphysical simplifying assumptions and treats the associated signal processing and electromagnetic (EM) analyses independently, resulting in improper inclusion of the underlying physics (EM theory) of such systems and consequently leading to inaccurate and erroneous performance p...

In this paper, it is illustrated on how to carry out adaptive processing simultaneously at multiple frequencies using the same antenna array consisting of dissimilar antenna elements nonuniformly spaced and deployed in any environment. First, a transformation method is introduced to account for all non-ideal effects of an antenna deployed in a real...

This document presents the application of a new electromagnetic in-house parallel EM simulator to the antenna analysis. The simulator is included in the commercial software HOBBIES. HOFEM makes use of a weak formulation based on double curl vector wave equation discretized with the higherorder isoparametric curl-conforming tetrahedral and triangula...

In electrical engineering, we obtain maximum average power from a source with some internal impedance when the connected load impedance equals the complex conjugate of the internal source impedance. This is known by the maximum power transfer theorem. Applying this theorem means that the best we can do is to distribute the source power equally betw...

The objective of this review paper is to illustrate the principle of analytic continuation and provide its relationship to reduced rank modelling using the total least squares based singular value decomposition methodology. The principles are illustrated in the different domains using the Matrix Pencil Method and the Cauchy Method for various reduc...

One of the objectives of this presentation is to illustrate how Maxwell came to his mathematical constructs of the work done before him by Oersted , Ampère, Faraday, Gauss, and so on, into a concise and precise mathematical form. In addition, the chapter addresses two specific topics which are fundamental in engineering electromagnetic education: h...

The objective of this chapter is to illustrate that an electromagnetic macro model can accurately predict the dominant component of the propagation path loss for a cellular wireless communication. The reason a macro model can provide accurate results that agree with experiments is because the trees, buildings, and other man-made obstacles contribut...

Conventionally, the design of antennas is narrowband and little attention is paid to the phase responses of the devices as functions of frequency. Even the use of the term broadband is misleading as one essentially takes a narrow band signal and sweeps it across the band of interest. In fact, it is not necessary to pay too much attention to the pha...

The far field of an antenna is generally considered to be the region where the outgoing wavefront is planar and the antenna radiation pattern has a polar variation and is independent of the distance from the antenna. Hence, to generate a locally plane wave in the far field the radial component of the electric field must be negligible compared to th...

In electrical engineering, we obtain maximum average power from a source with some internal impedance when the connected load impedance equals the complex conjugate of the internal source impedance. This is known by the maximum power transfer theorem. Applying this theorem means that the best we can do is to distribute the source power equally betw...

The far field of an antenna is generally considered to be the region where the outgoing wavefront is planar and the antenna radiation pattern has a polar variation and is independent of the distance from the antenna. Hence, to generate a locally plane wave in the far field the radial component of the electric field must be negligible compared to th...

Recently, Schelkunoff integrals have been used to formulate a Green's function for analysis of radiation from a vertical electric dipole over an imperfect ground plane. Schelkunoff integrals were proved to be more suitable for numerical computation for large radial distances than the Sommerfeld integrals which are used conventionally to deal with a...

To alleviate the computational bottleneck of a powerful two-dimensional self-adaptive finite element method (FEM) for the analysis of open region problems, which uses an iterative computation of the Integral Equation over a fictitious boundary for truncating the FEM domain, we propose the use of Adaptive Cross Approximation (ACA) to effectively acc...

The requirements for the VGOS (VLBI Global Observation System) [1] are: feed system covering the 2 to 14 GHz bandwidth and also working with high efficiency (> 50%). Universidad Carlos III de Madrid has developed a new topology to cover them. The new receiver topology is based on a log-spiral antenna printed on a conical surface. Two interesting ch...

VLBI2010 requires a feed that simultaneously has high efficiency over the full 2−14 GHz frequency range. The simultaneity requirement implies that the feed must operate at high efficiency over the full frequency range without the need to adjust its focal position to account for frequency dependent phase center variations. Two feeds meet this specif...

In In this presentation, a source reconstruction on a surface close to the antenna of interest is proposed to obtain the set of equivalent currents representing the forward and backward radiation fields of an antenna whose near field pattern has been measured. Once these equivalent sources are determined, the electromagnetic fields at any aspect an...

In this paper, we show how to eliminate shadow fading in cellular wireless system and discuss the main reason for such a phenomenon. One can deploy the transmitting antenna closer to the ground. In that case, the region of the variation in the field strength (shadow fading region) would be quite small and the field strength will decay monotonically...

The purpose of this article is to demonstrate that the conventional S-parameters cannot be applied to devices having complex characteristic impedances as in some cases the reflection coefficient can be greater than 1 even when terminated by a passive conjugate load for maximum power transfer. This is particularly pertinent for antenna problems. Als...

The Electrically Small Antennas (ESAs) perform well compared to larger antennas under matched conditions. In this paper, we study the difficulties in achieving a good design of an ESA matched to 50 O system. These difficulties are summarized in three topics: First, the Quality (Q) factor of an ESA, in general, is high and cannot be less than the Ch...

In this paper, we study the performance of the Electrically Small Antennas (ESAs) versus larger antennas in both transmitting and receiving modes. We conclude that the ESAs perform well compared to larger antennas under matched conditions where the input power to the antenna is real (input power is S = V in I in , V in and I in are the phasor domai...

This document presents a new electromagnetic in-house parallel EM simulator named HOFEM (Higher Order Finite Element Method). The simulator makes use of some of the research developments on the area made within the Group of Radiofrequency, Electromagnetism, Microwaves and Antennas (GREMA) of the Universidad Carlos III de Madrid to which the authors...

This paper presents the effect of broadband matching in simultaneous information and power transfer along with an implementation. The narrowband characteristic of antennas has limited the applications of simultaneous information and power transfer. The performance improvements in terms of channel capacity and power delivery under broadband matching...

A new boundary integral method for solving the general Helmholtz equation has been developed starting from the frequency independent Laplace's equation. The new formulation is based on the Method of Moments solution of Laplace's equation. The main feature of this new formulation is that the boundary conditions are satisfied independent of the regio...

In electromagnetics, time reversal was first examined in the fifties of the twentieth century. Whereas in acoustics, time reversal was first experimented in the nineties. In the current literature on electromagnetics, antennas and propagation and wireless communications, time reversal is frequently referred to as a technology that first appeared in...

Two patch resonator filters, namely Type I and Type II, are designed using a slot composed of multiple circular sectors. The filters operate in the 2.4-2.48 GHz wireless local area network (WLAN) frequency. The measured 3 dB insertion loss bandwidth of the filters covers the whole WLAN band. The stopband of the Type II filter is below 2.18 GHz and...

Many authors have published methods to synthesize microwave filters that provide a circuit prototype composed of ideal resonators and ideal couplings between them. Usually, the implementation step of that network with a particular technology is provided with few details. This work presents a method to synthesize a rectangular waveguide filter with...

A compact diplexer fabricated on substrate-integrated waveguide (SIW) technology is presented. The diplexer is a sixth order coupled-resonator network with no additional elements such as power dividers, composed exclusively of three dual-mode square SIW cavities. The coupling between the two orthogonal resonant modes of each cavity is generated by...

The objective of this presentation is to illustrate the accuracy of the Schelkunoff formulation over the Sommerfeld solution for a vertical electric dipole radiating over an imperfect ground. In an earlier paper, the alternate form of the Sommerfeld Green's function developed by Schelkunoff was presented (Schelkunoff, 1943 and Dyab, 2013). Here we...

Received signal level measurements are frequently used to check the performance and the Quality Of Service (QOS) inside the coverage area in cellular networks. These expensive time consuming measurements are carried out using actual drive tests to assess the coverage area of a base station for a given cell and thus evaluate the QOS. In a drive test...

Received signal level measurements are frequently used to check the performance and the Quality of Service (QOS) inside the coverage area in cellular networks. These expensive time consuming measurements are carried out using an actual drive tests to assess the coverage area of a base station for a given cell and thus evaluate the QOS. In this pape...

Received signal level measurements are frequently used to check the performance and the Quality of Service (QOS) inside the coverage area in cellular networks. These expensive time consuming measurements are carried out using an actual drive tests to assess the coverage area of a base station for a given cell and thus evaluate the QOS. In this pape...

This paper illustrates a method to carry out adaptive processing simultaneously at multiple frequencies using the same antenna array located over imperfect ground planes. First, it is shown how to transform an array situated over an imperfect ground to a uniformly spaced array of point radiators. Then, a direct data domain least squares (D3LS) meth...

The two historical topics that are so fundamental in electromagnetic education are addressed in this talk. It is not well recognized that Maxwell reached the conclusion light was electromagnetic in nature before he wrote his 20 equations which were reduced to the four that we use today by Hertz and Heaviside. In addition, Maxwell did not have the b...

Recently, Schelkunoff integrals were exploited to formulate a physics-based Green's function for analysis of vertical electric dipole radiation over an imperfect ground plane (W. Dyab, T. Sarkar, and M. Salazar-Palma, IEEE transactions on Ant. & Prop. vol. 61, no. 8, August 2013). Schelkunoff integrals were proved to be much more suitable for numer...

Surface electromagnetic modes guided by thin metal layers are usually called surface plasmons SP. SP were originally discovered by Ritchie in the fifties of the twentieth century in the optical regime. Then, surface plasmons found many applications in different areas of science including terahertz and microwave devices. Departing from optics to rad...

A compact diplexer fabricated on substrate-integrated waveguide (SIW) technology is presented. The diplexer is a coupled-resonator network with no additional elements such as power dividers, composed exclusively of six SIW resonators coupled through inductive irises, with one transmission zero at each channel that improves the selectivity. The clos...

This communication presents an alternate methodology— parasitically coupled feed—for exciting a four element microstrip array radiating primarily in the broadside direction. Typically, a four element microstrip array is fed directly through a corporate feed network using T-junctions and quarter wave transformers. The proposed parasitically coupled...

The far field pattern from a nonuniformly spaced antenna array is computed using a least squares method. The method originally developed for spectral estimation for a nonuniformly spaced finite data set is applied for the analysis of the far field pattern from unevenly spaced antennas, as the far field pattern is due to the spectrum of the location...

A function-reconfigurable double-helix printed antenna, inspired by DNA structures, is proposed. The antenna, consisting of two metal strips printed on a substrate, was designed, optimized, and fabricated. It was more stable than a metal-wire antenna. The antenna was demonstrated to have a remarkable functional reconfigurability with different lump...

The future of computational electromagnetics is changing drastically with the new generation of computer chips, which are multi-core instead of single core. Previously, advancements in chip technology meant an increase in clock speed, which was typically a benefit that computational code users could enjoy. This is no longer the case. In the new roa...

Numerous recent publications have focused on the Pareto-based multi-objective optimization algorithm using the genetic algorithm for better design of microwave communication circuit components. This optimization technique can be introduced to researchers and engineers to facilitate the development of wireless technology. To translate the research o...

When one computes the natural resonant singularity expansion method (SEM) poles for a dielectric sphere composed of different materials, one is surprised to observe that these SEM poles do change too much with corresponding changes in the value of the permittivity and permeability. This article provides an analytical solution as to why it is so. Th...

The objective of this presentation is to illustrate that the use of a higher order basis can significantly reduce the size of the problem that needs to be solved numerically. Hence problems that require supercomputers to solve can be solved on desktop computers. These concepts will be utilized to illustrate the advantages for integral equation meth...

This paper presents a thin and compact high gain planar antenna integrated with a CMRC compact filter. The high gain antenna is a 4 element broadside microstrip array fed by parasitic coupling. The antenna is developed on a thin substrate of 0.762 mm thick. The broadside gain is 11.37 dBi at 5.5 GHz. The CMRC filter has filtered out the higher orde...

The future of computational electromagnetics is CHANGING DRASTICALLY with the new generation of computer chips which are multi-core instead of single core. Previously, advancements in chip technology meant an increase in clock speed, which was typically a benefit that computational code users could enjoy. This is no longer the case. In the new road...

The objective of this presentation is to illustrate the art of writing a parallel code that exploits an out-of-core solver.

This paper presents an automatic optimization routine for simultaneous optimization of a large number of unknowns.

Some researches showed that a single conductor wire can transmit signals. We tried to duplicate these results and we can see a single conductor wire does transmit signals. But its performance is very poor, especially when the wire is not a straight wire. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:124–127, 2014

This letter presents two configurations of thin and compact dual-band four-element broadside patch antenna arrays. They are built by feeding four dual-band patch radiating elements through a feeding patch by parasitic coupling. Similar to the electrically steerable passive array radiator (ESPAR), a driven element is directly excited from the power...

A plethora of papers can be found in the scientific literature talking about time reversal. The term time reversal exists in the publications in a variety of different fields, such as ultrasonics, acoustics, wireless communications, electromagnetics, antennas and propagation, optics, physics, and philosophy. The term time reversal by itself sounds...

This letter proposes a design of a multisection phase correcting network to reduce the phase error of broadband differential phase shifters. The phase correcting network is constructed by a pair of parallel multisection coupled lines. With the use of the phase correcting network, the experimental result of the phase deviation is reduced from 6.4 °...

Sommerfeld integrals appear in the solution of radiation and scattering problems involving antennas in planar multi-layered media. In the conventional approach it is quite difficult to numerically integrate the tails related to Sommerfeld integrals as they are not only oscillatory but also slowly decaying. Numerous research efforts have been develo...

The purpose of this paper is to demonstrate that the recently published paper [1] dealing with little known facts and some new results on transmission lines is due to an incomplete interpretation of the nonphysical artifacts resulting from a particular mathematical model for the S parameters. These artifacts are not real and do not exist when a dif...