A simple slot coupled dual-band circularly polarized (CP) rectangular dielectric resonator antenna (DRA) is presented. The TE₁₁₁ and TE₁₁₃ modes of the rectangular DRA are excited by a modified annular slot. Working principle of the proposed antenna is explained in this paper. Design guideline of the proposed antenna is also devised based on the parameter study. The simple feeding and radiating structures of the proposed antenna make it easy to be designed and fabricated. A prototype antenna was designed, fabricated and measured. The simulated and measured results confirm the dual-band CP performance of the proposed antenna.

We study the magneto-permittivity effect in a magnetized plasma with appropriately designed parameters. We show that at frequency near the plasma frequency, magneto-optical activity plays an important role to manipulate and control the wave propagations in the magnetized plasma. Such a unique feature can be utilized to establish sensitive magnetic field switching mechanism, which is confirmed by detailed numerical investigations. Switching by magnetic field based on magnetized plasma is flexible and compatible with other optical system; moreover it is applicable to any frequency by tuning the plasma density. For these reason, our work shows the possibility for developing a new family of high frequency and ultrasensitive switching applications.

For the first time, the higher-ordered modes of a stepped-impedance slotline resonator are closely combined for designing the broadband in-phase andout-of-phase power dividers. It was found that the output phases of the two modes can be easily reversed at the same time by changing the direction of their feeding currents. For this configuration, interestingly, a multifunctional power divider which is reconfigurable to produce either in-phase or out-of-phase signals can be easily designed from its passive counterparts by incorporating multiple RF diodes into the output feedlines, leading to significant cost saving and high compactness. The design procedure and equations of the power-dividing structures are discussed.

A novel direction of arrival (DOA) and polarization estimation method with sparse conical conformal array consisting of concentred loop and dipole (CLD) pairs along the z-axis direction is proposed in this paper. In the algorithm, the DOA and polarization information of incident signals are decoupled through transformation to array steering vectors. According to the array manifold vector relationship between electric dipoles and magnetic loops, the signal polarization parameters are given. The phase differences between reference element and elements on upper circular ring are acquired from the steering vectors of upper circular ring, it can be used to give rough but unambiguous estimates of DOA. The phase differences are also used as coarse references to disambiguate the cyclic phase ambiguities in phase differences between two array elements on lower circular ring. Without spectral peak searching and parameter matching, this method has the advantage of small amount of calculation. Finally, simulation results verify the effectiveness of the algorithm.

We investigate the electromagnetic wave propagation across a finite inhomogeneous and anisotropic cylindrical metamaterial composite containing both positive and negative effective refractive index parts with linear spatial gradient. Exact analytical solutions for the electric and magnetic field distributions are obtained for a linear variation of effective refractive index across the structure. The model allows for general temporal dispersion and uniform losses within the composite.

The matrix method for the calculation of antenna far-field using irregularly distributed near-field measurement data is presented. The matrix method is based on the determination of the plane wave expansion (PWE) coefficients from the irregular near-field samples using a matrix form that connects the radiated field with the corresponding plane wave spectrum. The plane wave spectrum is used to determine the far-field of the antenna under test (AUT). The matrix method has been implemented, and its potentialities are presented. The validations using analytical radiating model (dipoles array) and experimental measurement (X band standard gain horn antenna) results have demonstrated the efficiency and stability of the proposed method.

A microstrip antenna design is introduced in which aperture coupled rectangular microstrip patch is coupled electromagnetically with a parasitic gridded rectangular patch placed above. The gridded patch consists of nine identical rectangular parts separated by a distance which is much smaller than a free space wavelength for a central frequency. The antenna is designed to operate in the 60 GHz band and is fabricated on a conventional PTFE (polytetrafluoroethylene) thin substrate. Different published arrangements for parasitic patches are studied. For the same substrate and central frequency the proposed antenna has improved return loss bandwidth and gain bandwidth for approximately the same maximum gain. Measurement results are in good agreement with simulation. Measured 10 dB return loss bandwidth is from 54 GHz up to 67 GHz. It fully covers the unlicensed band around 60 GHz. The measured antenna realized gain at 60 GHz is close to 8 dB, while the simulated antenna radiation efficiency is 85%. A simple beam shifting method is possible for this antenna structure by connecting adjacent outside parts in the gridded patch. The designed antenna is suitable for a high speed wireless communication system in particular for a user terminal in a fifth generation (5G) cellular network.

This paper presents a novel approach for solving the frequency responses of a powerline network, which is a two-parallel-conductor system with multiple junctions and branches. By correcting the reflection coefficient and transmission coefficient of each junction, a complex network can be decomposed into several, single-junction, units. Based on the Baum-Liu-Tesche (BLT) equation, we preliminarily propose the calculation method of frequency responses for single-junction network. In accordance with the direction of power transfer, we calculate the frequency responses of loads connected to each junction sequentially, from the perspective of the network structure. This approach greatly simplifies the computational complexity of the network frequency responses. To verify the proposed algorithm, networks with various numbers of junctions and branches are investigated, and the results are compared with a commercial electromagnetic simulator based on the topology. The analytical results agree well with the simulated ones.

Pneumothorax is the medical condition caused by the air concentration inside the pleural cavity, the space between the lung and the chest wall. Apart from traditional diagnostic methods, it can be detected by using microwave sensors that capture variations in reflected electromagnetic field (EMF). Sex and obesity, related to the internal composition of the biological tissues, can influence the reflected EMF and therefore the sensor diagnostic ability. This paper investigates the effect on the performance of a proposed on-body dual-patch antenna sensor for pneumothorax diagnosis, due to inter-subject variability in underlying tissue structure. The sensor operates at frequency range of 1-4 GHz. The challenge of the paper is to propose frequency bands for robust and safe sensor operation. S₁₂ parameter alternation versus frequency is assessed for healthy and pathological cases. Implemented thorax numerical models include modified (i) closed rectangular multilayered and (ii) MRI-based anatomical ones. In rectangular models, thickness and configuration of muscle, fat and bone tissues are varied, according to literature. Additionally, sex-related anatomical differences are taken into account in MRI-based models. All scenarios are solved using Finite Difference Time Domain method. Results revealed that the proposed frequency bands lie within 1-2.7 and 2.9-3.5 GHz, for muscle, 1.4-3.5 GHz for fat and 1-2.2 and 2.8-3.5 GHz, for bone variations. Numerical evaluations for accurate anatomical models verify the findings.

A new printed helical antenna (PHA) for a circularly polarized (CP) titled beam is proposed. With the introduction of a multiple sections technique into the PHA's helical arm, the antenna radiates a CP titled beam. To feed the antenna, a matching network composed of a 50 Ω microstrip transmission line and two symmetrical λ₀/8 open stubs is designed. The simulated and measured results show that the PHA radiates a CP tilted beam with a maximum radiation direction of (θ_max, φ_max) = (32°, 135°) at f₀ = 2.11 GHz. The measured bandwidth with a reflection coefficient lower than −10 dB is 11.8% (1.99-2.24 GHz), and the experimental results for the radiation pattern, gain, and axial ratio (AR) are also presented.

This paper describes a novel technique which has the potential to make a significant impact on the mapping of the human brain. This technique has been designed for 3D full-wave electromagnetic simulation of waves at very low frequencies and has been applied to the problem of modeling of brain waves which can be modeled as electromagnetic waves lying in the frequency range of 0.1-100 Hz. The use of this technique to model the brain waves inside the head enables one to solve the problem on a regular PC within 24 hrs, and requires just 1 GB of memory, as opposed to a few years of run time and nearly 200 Terabyte (200,000 GB) needed by the conventional FDTD (Finite Difference Time Domain) methods. The proposed technique is based on scaling the material parameters inside the head and solving the problem at a higher frequency (few tens of MHz) and then obtaining the actual fields at the frequency of interest (0.1-100 Hz) by using the fields computed at the higher frequency. The technique has been validated analytically by using the Mie Series solution for a homogeneous sphere, as well as numerically for a sphere, a finite lossy dielectric slab and the human head using the conventional Finite Difference Time Domain (FDTD) Method. The presented technique is universal and can be used to obtain full-wave solution to low-frequency problems in electromagnetics by using any numerical technique.

This paper presents a miniaturized tunable bandpass filter, consisting of two coaxial dielectric resonators and a pair of parallel-coupled lines. A coaxial dielectric resonators and a microstrip line form a new step-impedance resonator (SIR), which is different from a conventional SIR. Varactor diodes are connected to SIRs to tune the center frequency. The gap between parallel-coupled lines controls the inter-stage coupling coefficient. Lumped inductors used for coupling to I/O ports can reduce design complexity. The variations of coupling coefficient and external quality factor with tuning frequency are analyzed using HFSS software. A appropriate coupling coefficient which satisfies with constant fractional bandwidth within the tuning range is available. A tunable filter has been made of dielectric ceramics with dielectric constant of 38, fabricated on dielectric substrate and measured using Networks analyzer. Center frequencies vary from 0.43 GHz to 0.78 GHz, 3 dB fractional bandwidth from 6.4% to 6.8% when bias voltages are applied from 0 V to 10 V. The measured results validate the approach and agree with the simulation.

This paper gives a comprehensive study on the modeling and design challenges of Through Silicon Vias (TSVs) in high speed three dimensional (3D) system integration. To investigate the propagation characteristics incurred by operations within the ultra-broad band frequency range, we propose an equivalent circuit model which accounts for rough sidewall effect and high frequency effect. A closed-form expression for TSV metal oxide semiconductor (MOS) capacitance in both depletion and accumulation regions is proposed. The coupling of TSV arrays and near and far field effect on crosstalk analysis are performed using 3D EM field solver. Based on the TSV circuit model, we optimize the TSVs' architecture and manufacturing process parameters and develop effective design guidelines for TSVs which could be used to resolve the signal integrity issues arising at high frequency data transmission in 3D ICs.

An internal dual-band flexible antenna is described. The antenna employs a rectangular patch to improve the interrogation range (above 100 mm) for near-field communications (NFC), as well as the passive average gain performance (above -20 dBi) for FM radio. A preliminary prototype antenna exhibits an interrogation range of 110 mm at 13.56 MHz and a passive average gain performance from -15.6 to -13.5 dBi in the range 86-108 MHz, while demonstrating an omnidirectional radiation pattern for FM radio applications.

Nowadays the mobile personal communication systems and wireless networks are commonly used. Experience has revealed that the antennas suitable for these applications should have small size and operate in assigned different frequency bands. For this purpose, circularly polarized (CP) multi-band square microstrip antenna with three N-slots and a pair of truncated corners is proposed, designed and simulated. To reduce the losses and improve the antenna efficiency in addition to the bandwidth, an efficient electromagnetic band gap (EBG) structure is introduced. The proposed antenna has produced a higher efficiency, an improved operational bandwidth, and a higher gain relative to the conventional microstrip antenna.

The configuration of a new circularly polarized microstrip antenna with omnidirectional radiation pattern for GPS-L1 application is proposed in this paper. The designed antenna has a back-to-back rectangular-patch structure, and two patches are fed by coaxial cable connected with a Wilkinson power divider. The horizontal omnidirectional radiation pattern was achieved by both simulation and measurement. Axial ratio in the peak gain plane was around 3 dB ranging from 1.5 dB to 3.6 dB. The variation of RHCP gain in the horizontal omnidirectional circular polarization plane was smaller than ±1 dBic. And peak RHCP gain of the designed antenna was about 2.3 dBic.

Use of discontinuities in microstrip lines is currently employed to improve the performance of different passive circuits, including reduction of amplifiers, enhancement of filter characteristics and applications to suppress harmonics in patch antennas. This paper presents an improved method of size reduction of a microstrip antenna using Defected Microstrip Structure (DMS) that it is used to perform serious LC resonance property in certain frequency. The DMS is integrated in antenna structure, and therefore this method keeps the antenna size unchanged and makes a resonance frequency. This resonance is due to the abrupt change of current path of antenna that resonates at 5.8 GHz which is shifted to 2.69 GHz thanks to spiral DMS. A prototype of the antenna was fabricated with an FR4 substrate and tested.

The electromagnetic field equations are solved to give the 4-potential in Hermite-Gaussian beams as a function of both the 4-positions of the beam waist and each point in the field. These solutions are the sums of products of position-dependent complex 4-vectors and modified Bateman-Hillion functions. It is assumed that the time difference between the beam waist and each other point is equal to the distance between the points divided by the speed of light. This method is shown to generate solutions that preserve their forms under Lorentz transformations that also correspond to the well known paraxial solutions for the case of nearly parallel beams.

The deflection of charged particle beams by electric and/or magnetic fields is invariably based on the field centred approach associated with Maxwell-Lorentz and incorporated into the Lorentz force formula. Here we present an alternative method of calculation based on the force formula of Weber-Ritz and which does not involve, directly, the field entities E and B. In this study we evaluate the deflection of an electron beam by a long solenoid carrying direct current and positioned centrally across the beam. The experiment has some bearing on the Aharonov-Bohm effect in that our calculations indicate that even for very long solenoids the classical force on the beam remains finite. The standard interpretation of the effect is, however, in terms of quantum mechanics and vector potential. Experimental measurements have been made of electron beam deflections by three solenoids, 0.25 m, 0.50 m and 0.75 m long; each solenoid is doubly wound with the same winding density (2600 turns per metre) and carrying the same current of 5.00 A d.c. Our results indicate that, within the limits of experimental error, both Weber-Ritz and Maxwell-Lorentz theories correlate with measurements for the longer solenoids. However in the case of the shortest solenoid, the lack of uniformity of the magnetic field, leads to significant error in the calculation of beam deflection by the Lorentz force. By contrast in a Weber-Ritz calculation a precise value of beam deflection is obtained by equating the impulse of the non uniform beam force to the vertical momentum change of the electron. This is a fundamentally different approach which uses a statistical summation of forces on the beam in terms of relative velocities between moving electrons and involves a direct computation of the vertical force on the beam due to the circling solenoid current. This method has distinct advantages in terms of economy; that is, it does not involve directly field entities E and B, nor the leakage flux from the solenoid or the vector potential.

Nowadays new safety related systems design include electromagnetic analysis (EMA) during their development. Each of these systems is composed by smaller apparatuses that contain electronic components able to emit electromagnetic (EM) waves. On the other hand, the usage of smaller integrated circuit increase their susceptibility to EM interference. Companies often underestimate the importance of emissions lower than standard limits. A method based on near-field (NF) to far-field (FF) transformation is introduced in order to evaluate radiated emission leakage. This study is an important novelty to analyze electromagnetic issues in the case of safety related systems. Moreover, authors presented how this method is positioned as to current standards. Effectively NF-FF is proposed for site survey analysis on assembled systems where EM leakages should be mitigated to avoid EM attacks. Tools and measurements presented here can be used to sketch the virtual EM (VEM) interface of device-under-test (DUT) in terms of emissions amplitude, frequency and direction. An opponent could use this information to jam these systems utilizing an attack model based on a circular antenna here presented. The results indicate that it is feasible to use this methodology to analyze EM radiated emissions starting from NF information. Compared with current immunity test levels, the EM attack planned on VEM interface characteristics can be deemed efficiently against safety related systems.