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Radiation from cylindrical leaky waves (CLWs) supported by layered dielectric media is of interest in a variety of current applications. A comprehensive two-part study has been undertaken to investigate the generation and the radiation properties of CLWs with an arbitrary integer azimuthal order $n$. The first of this two-part sequence deals with the identification of continuous rings of canonical sources of electric and magnetic types, capable of exciting higher-order CLWs (HOCLWs) in planar open radial waveguides. The relevant far-field radiation formulas are then derived, generalizing those already available in the literature for cylindrical waves with azimuthal orders $n=0$ and $n=1$ , i.e., those excited by elementary vertical or horizontal dipoles. Design guidelines for the practical excitation of HOCLWs through discrete sources, namely, circular phased arrays, are provided in the companion paper along with numerical validations and illustrative results in both the near-field and the far-field regions. [ABSTRACT FROM AUTHOR]

Stealth airborne systems are low observable platforms, which bring together technologies in the field of aerodynamics, electromagnetics, and material science. Radar absorbing materials/structures play a key role in the design of such stealth airborne platforms. In this paper, a radar absorber has been fabricated based on the design of a nonperiodic metallic patch coated with graphene. The simulation results of the novel design over an ultrawideband (1–60 GHz) yield good absorption (99.93%). With the constraint of fabrication facility, a small unit cell of the structure has been fabricated and measured. The measurement results show a good agreement with the simulation results. The absorption bandwidths, thickness, and weight of the structure are some of the key elements that were considered in the design model. It has been observed that the design allows the electric potential tuning by changing the Fermi energy of the graphene layer. The significant absorption of the proposed design in ultrawideband shows that it has potential applications in the RF stealth technology. [ABSTRACT FROM AUTHOR]

Recent work on developing novel integral equation formulations has involved using potentials as opposed to fields as unknown variables. This is a consequence of additional flexibility offered by potentials that enable development of well-conditioned systems. Until recently, most of the work in this area focused on formulations for analysis of scattering perfectly conducting objects. In this paper, we present well-conditioned decoupled potential integral equations (DPIEs) formulated for electromagnetic scattering from homogeneous dielectric objects. The formulation is based on decoupled boundary conditions derived for scalar and vector potentials. The resulting DPIE is a second kind integral equation, and does not suffer from either low frequency or dense mesh breakdown. Analytical properties of the DPIE are studied for spherical systems, and results provided demonstrate well-conditioned nature (and bounded spectrum) of the resulting linear system. [ABSTRACT FROM AUTHOR]

The theory, modeling, measurement, and analysis of the radiation characteristics of bond wire antennas (BWAs) is presented in this paper. We commence with rigorous formulations and derivations of analytical models for calculating the vector potential, radiated electromagnetic fields, and directivity of full-loop BWAs (FL-BWAs), considering nonconstant current distribution along the BWAs. Based on the image theory, we derive an analytical model for calculating the directivity of half-loop BWAs (HL-BWAs) from that of FL-BWAs. Very good correlation is obtained between the directivities calculated analytically using the derived models, and numerically using commercial full-wave solvers, thus validating our analytical approach. We apply the verified models to thoroughly analyze the radiation characteristics of FL-BWAs and HL-BWAs. The radiation characteristics of an HL-BWA are based on the assumption that its reference plane is infinitely large and perfectly conducting. However, for the development of wireless systems, reference planes of finite sizes are required. Therefore, we investigate the impact of realistic planes sizes. Our results reveal that the radiation characteristics of BWAs referred to as “HL-BWAs” in published literature differ significantly from those of true HL-BWAs. Therefore, we introduce the term “quasi-half-loop BWA (QHL-BWA)” to describe BWAs with small reference planes. For experimental verification, QHL-BWAs which operate in the 60 GHz band were fabricated using the wedge–wedge bonding process. Both S-parameter and radiation pattern measurements were performed. Very good correlation was obtained between measurement and simulation results. [ABSTRACT FROM AUTHOR]

This paper deals with the analytic determination of the current reflection coefficient for a wire above ground. The trajectory of the wire at the wire terminal is arbitrary and the wire is connected to the ground with an impedance. The reflection coefficient is approximated by an iterative approach for the solution of the so-called mixed potential integral equations. The iteration is initialized by the classical transmission line solution. The tangential electric field on the surface of the thin wire corresponding to the classical solution is then used as a distributed source to determine a correction term for the current. By this way, the scattering of the transverse electromagnetic modes at the discontinuity is included. Very good agreement between the analytic solution and a numerical one is observed. It is shown that broadband matching is not possible with a frequency-independent load. The importance of the incorporation of the high-frequency effects is highlighted by the evaluation of the natural frequencies for two specific wire configurations. [ABSTRACT FROM AUTHOR]

This paper presents a new perspective on the analysis of the cylindrical antenna theory. It applies the cylindrical surface waves on an infinitely long cylindrical conductor, which are similar to the Sommerfeld axial cylindrical surface waves, to describe the conventional postulate of applying a sinusoidal current distribution on a cylindrical dipole antenna. This treatment leads to the derivation of simple expression for the current on a cylindrical dipole antenna of finite conductivity, which is in good agreement with the current obtained from the three-term approximations. Also, it proposes an expression for the current on an infinitely long cylindrical dipole antenna of finite conductivity, which is also in good agreement to the current found from applying the Fourier transform technique. Moreover, this paper shows that the complex propagation constant used in the three-term approximation is similar to the complex propagation constant of the principal Sommerfeld wave on the surface of an infinitely long cylindrical conductor. Therefore, a more accurate representation of the current near the feeding point is proposed based on the complex propagation constants of multiple Sommerfeld waves. [ABSTRACT FROM AUTHOR]

This paper is concerned with the scattering of a time-harmonic electromagnetic (EM) plane wave (PW) by a fast and slow moving perfectly electric conducting circular cylinder under the framework of Einstein’s special relativity. By applying the Lorentz and EM field transformations to the scatterer comoving frame of reference, the problem is mapped into a PW scattering from a stationary cylinder. By using the well-known (stationary cylinder) exact and asymptotic solutions, we obtain the scattered EM field in this frame. These fields are then mapped back to the incident-field frame of reference. This procedure yields the exact and asymptotic scattered EM fields. We discuss several relativistic wave phenomena such as shifted shadow regions, velocity-dependent incident, and reflection angles and velocity-dependent creeping waves to name a few. Finally, we apply a low-speed approximation to the wave potentials and discuss the corresponding wave phenomena. [ABSTRACT FROM AUTHOR]

In this paper, we propose a potential-based integral equation solver for low-frequency electromagnetic (EM) problems. In this formulation, the scalar potential ( \Phi ) equation is solved in tandem with the vector potential ( \textbf {A} ) equation. The resulting system is immune to low-frequency catastrophe and accurate in capturing the electrostatic and magnetostatic physics. The fast convergence of the new \textbf {A}$ - $\Phi $ system, which is a typical symmetric saddle point problem, is made possible through the design of an appropriate left constraint preconditioner. Numerical examples validate the efficiency and stability of the novel formulation in solving both EM scattering and circuit problems over a wide frequency range up to very low frequencies. [ABSTRACT FROM PUBLISHER]

Applied modeling of electromagnetic interactions with linear conductors is essential to advance near-earth sensing devices and integrated signal processing algorithms. This paper describes the development of a novel analytical transmission line (TL) model and its subsequent comparison with a method of moments simulation. The TL model predicts electromagnetic scattering by a linear conductor of finite length that is near lossy ground, here assumed to be a homogeneous conducting half-space. Our model uniquely combines the following: the effect of surface waves on the fields, the proximity of the air–ground interface on wave propagation along the conductor, orthogonal electric dipole exciter polarizations, and the role of an insulating layer on the conductor. It is shown that the TL approach is accurate and offers advantages such as fast computation time, physical insight into the scattering process, and potential for embedded signal processing. [ABSTRACT FROM PUBLISHER]

This paper presents a multifeed antenna structure that synthesizes the desired far-field radiation characteristics with on-antenna power combining and increases the total radiated power of a wireless transmitter. The driving signals at the multiple antenna feeds are scaled properly in amplitude and phase, so that they collectively synthesize the desired on-antenna current/voltage distribution and achieve the resulting desired far-field radiation pattern. The proposed multifeed antenna offers flexibility to optimize the antenna driving impedances based on the locations of the feeds. It also simplifies the passive impedance matching and power-combining networks between the antenna feeds and the transmitter outputs, substantially increasing the total transmitter power efficiency. Most importantly, the proposed multifeed antenna achieves on-antenna low-loss power combining, which, compared with antenna array-based spatial power combining, does not suffer from narrowed beamwidth or enlarged antenna panel size. As proof of concept, multifeed slot antennas and a multifeed square loop antenna are designed and characterized at 10.3 GHz. Conventional single-feed slot antennas and a single-feed square loop antenna are also implemented as reference designs. Well matched antenna gains and radiation patterns between the proposed multifeed antennas and the conventional single-feed antennas are achieved in the measurements, demonstrating the on-antenna power combining of the proposed multifeed antennas without distorting the far-field radiation patterns. [ABSTRACT FROM PUBLISHER]

This paper discusses a spherical scatterer whose anisotropy axes are defined by the spherical coordinates. Such a scatterer is called systropic sphere. Electrostatic scattering from systropic spherical objects has been studied earlier but with some restrictions. This paper provides a generalized method for studying the systropic sphere. More specifically, the paper focuses on the electrostatic scattering of the systropic sphere described by two quantities: the axial and the transverse polarizabilities. The axial polarizability does not depend on the azimuthal permittivity component, which simplifies the problem sufficiently to make it a subject to an analytical approach. In contrast, the transverse polarizability depends on the azimuthal permittivity component, which makes the problem complex enough to require a semi-analytic approach. This paper describes a novel way to study the systropic sphere. An important parameter in the systropy research is the ratio between the two tangential permittivity components, called systropy ratio. The novel method drastically extends the scope of the systropy research, by allowing a wider range of systropy ratios, a range that covers the whole set of positive real numbers. While the range of systropy ratios has been formerly restricted to square numbers, the new method that uses Gegenbauer polynomials, can solve the more general case. [ABSTRACT FROM AUTHOR]

A 3-D bidirectional solution to the parabolic approximation of the wave equation is investigated by using a vector field representation. The backward propagating wave is integrated to the classical parabolic equation approach, which represents the forward propagating wave. Propagation over flat terrain in the presence of knife-edges is considered as well as over irregular terrain consisting of hills modeled by the succession of knife-edges. At each knife-edge, appropriate boundary conditions are enforced, and the wave is partly reflected in the backward direction. The wave is marched in both directions by using the split-step algorithm. Different tests are conducted in order to analyze and validate the results obtained by the proposed algorithm. Comparisons with results from both, 2-D parabolic equation-based algorithm, and 3-D finite-difference time domain-based algorithm, are presented in this paper. [ABSTRACT FROM PUBLISHER]

In this paper, a simple but very accurate circuit model for two-port (split) loop antennas typically used for direction finding in the HF-band is presented. The circuit model consists of lumped elements and can be used to accurately estimate the input impedances and received voltages of two-port loop antennas in receive mode. It is shown that the same circuit model can be reduced to predict the input impedance behavior of a single-port loop antenna with much more accuracy than the existing transmission line and lumped element models over a wide frequency range. The model is shown to be valid for frequencies up to a point where the loop circumference is about a wavelength. The same circuit model in receiving mode can provide the 3-D radiation pattern of the antenna. [ABSTRACT FROM AUTHOR]

This paper proposes an augmented electric field integral equation (A-EFIE) for layered medium Green's function. The newly developed matrix-friendly formulation of layered medium Green's function is applied in this method. By separating charge as extra unknown list, and enforcing the current continuity equation, the traditional EFIE can be cast into a generalized saddle-point system. Frequency scaling for the matrix-friendly formulation is analyzed when frequency tends to zero. Rank deficiency and the charge neutrality enforcement of the A-EFIE for layered medium Green's function is discussed in detail. The electrostatic limit of the A-EFIE is also analyzed. Without any topological loop-searching algorithm, electrically small conducting structures embedded in a general layered medium can be simulated by using this new A-EFIE formulation. Several numerical results are presented to validate this method at the end of this paper. [ABSTRACT FROM AUTHOR]

The purpose of this paper is to present a robust and fast beamforming algorithm for the low-cost mobile phased array antennas. The proposed beamforming algorithm uses a sequentially perturbation gradient estimation method to update the control voltages of the phase shifters, with the objective of maximizing the received power by the array. This algorithm does not require either the knowledge of phase shifter characteristics or signal Direction-of-Arrival. Moreover, in this paper, the algorithm parameters are derived for the stationary and mobile platform configurations. For the stationary array, it is shown how the proper selection of the beamforming parameters limits the noise effects and increases the array output power. For the mobile array, a condition for the fast convergence is derived and the advantage of using nonuniform step size to update the control voltages is illustrated. When phase shifters suffer from the imbalanced insertion loss the proposed beamforming technique perturbs the phase-conjugate condition to increase the total received power. This algorithm has been implemented with the low-cost microwave components and applied to a Ku-band phased array antenna with 34 sub-arrays. The experimental results verify the broadband performance, and the fast convergence of the algorithm for different platform maneuvers. [ABSTRACT FROM AUTHOR]

Health-care monitoring and diagnostics technology continues to be of great interest in research due to an increasing trend in the number of people with chronic diseases. To improve accuracy and timeliness of diagnosis, electronic devices could be implanted inside human body to provide various real-time diagnostic information. However, effective technique for communicating the implant with outside world is still an open problem. Early efforts based on radio wave propagation are standardized as the medical implant communication services (MICSs) for 402–405-MHz frequency range, which was later adopted as medical device radiocommunication services for 401–406-MHz frequency range. Intrabody communication (IBC) is a relatively new technique that uses the human body as a channel with communication frequencies not exceeding several megahertz. In this paper, we propose a new analytical electromagnetic model that uses galvanically coupled IBC as an alternative to radio wave-based implant communication. The model is unified in the sense that it is based on multilayered ellipsoidal geometry that can be applied to any part of the body (i.e., head, torso, limbs, and so on). Our model effectively describes the influences of tissue layer thicknesses and electromagnetic properties, implant size and depth, and geometry of the body part. The model proves the security and low power consumption of IBC. The path loss characterization of IBC implants shows lower values compared with their MICS counterparts. [ABSTRACT FROM AUTHOR]

When a receiving antenna array operates on a complex environment, the ideal phase differences of the receiving voltages of the antenna array are significantly distorted by both mutual coupling and platform scattering. This distortion causes performance degradation of the direction of arrival (DOA) algorithms. For estimating and compensating for the phase distortion, an analysis of the receiving voltages of the receiving antenna array on the platform is required. In this paper, we propose a hybrid UTD-ACGF technique for modeling port voltages of the receiving antenna array on a complex environment. The complex environment is modeled by UTD technique, and the antenna array is modeled by ACGF. In order to explain the coupling effect between the complex environment and the antenna array, we use the first perturbation series approximation based on the exact mutual coupling perturbation series. The hybrid UTD-ACGF results are verified through comparison to MoM results. Finally, we statistically define a distortion matrix that has a relation between the distorted port voltages and the ideal port voltages. The distorted port voltages are evaluated using the hybrid UTD-ACGF technique as a backbone. In order to enhance the performance of the DOA algorithm, we efficiently estimate and compensate for the distortion matrix. A DOA simulation using the MUSIC algorithm is performed to confirm the compensatory effect of the distortion matrix. [ABSTRACT FROM PUBLISHER]

Conventional resonant-slotted waveguide arrays can only achieve a few percent of impedance bandwidth. This paper presents a new substrate-integrated waveguide (SIW)-based 60-GHz resonant-slotted waveguide array, which can achieve both wide impedance bandwidth and high gain. In the design, resonant slots with different resonant frequencies are arranged at unequal spacing along the SIW. The variance of the excitation voltages of different resonant slots is minimized to improve the arrays’ impedance bandwidth and gain. A \bf 4 \times \bf 1-element subarray is designed accordingly, which shows a - \bf 10\mbox-\bf dB impedance bandwidth from 56.5 to 66.7 GHz (16.6%) with a peak broadside gain of 11.5 dBi. Based on this subarray, three other arrays with \bf 4 \times \bf 4, \bf 8 \times \bf 4, and \bf 8 \times \bf 8-slot elements are designed, fabricated, and measured. Long nonresonant slots are placed between each two subarrays to improve isolation. Measured results of the three fabricated arrays show - \bf 10-dB impedance bandwidths of 20.8%, 22.4%, 18.8%, respectively, and peak broadside gain of 18.3, 19.9, and 22.8 dBi, respectively. The proposed structures exhibit wider impedance bandwidth and higher peak gain than their former counterparts. [ABSTRACT FROM PUBLISHER]

This paper discusses a spheroidal scatterer in a uniform, static electric field. The scatterer is assumed to be anisotropic and inhomogeneous in a way that relates to the spheroidal coordinate systems, that come in two varieties. The study expands on former research conducted upon radially anisotropic (RA) spheres. The new class of objects concerned resembles the formerly studied RA spheres, with the distinction that spheroidal instead of spherical coordinate system determines the axes of anisotropy. An analytical method to tackle the problem is developed. The results are validated analytically by comparing well-known special cases of spheroids: spheres, disks, and needles. [ABSTRACT FROM PUBLISHER]

A novel design of dual-band reconfigurable slot antenna is proposed in the paper. The configuration of the proposed antenna is based on a folded slot with a branch edge formed by multiple strips loaded with circuit components. In the design, the antenna is decomposed into networks, and the corresponding equivalent circuits are deduced. By applying resonant condition on the equivalent circuit at the desired center frequencies, the circuit components can be determined. The proposed design is later transformed into a reconfigurable antenna by using varactors. The antenna configuration is also modified for applying biasing voltages to varactors. Dual-band reconfigurable operation of antenna is studied and demonstrated for S-band applications at 2.45 GHz and GPS at 1.227/1.381/1.575 GHz. The design approach is described in details. Also, antenna measurements are conducted for design validation. [ABSTRACT FROM PUBLISHER]

In [1], the integral representations with respect to the vertical wavenumber given in (14) and (15) of that paper for the potentials of a vertical Hertzian dipole above an arbitrary ground plane are incomplete and, consequently, incorrect. The errors made in [1] are of fundamental nature and the representations provided therein cannot be obtained from first principles for a material half-space. The purpose of the present comment is to derive correct representations adopting the same notation as in [1]. Here, we focus on the z-component of the secondary field only in region-1 above the horizontal interface. The corresponding expression for the field below the interface is obtained in a similar manner. [ABSTRACT FROM PUBLISHER]

In this work, we study the problem of characterizing electromagnetic radiation from given near-field electromagnetic measurements on an arbitrarily shaped surface. Due to the evanescent waves present in the near-field data the inversion procedure requires special treatment in order to recover a stable physical solution. Our proposed approach to this challenging inverse problem is to seek a sparse decomposition of the fields into elementary electric and/or magnetic dipole on an equivalent source surface. As we show in this paper the incorporation of a sparsity constraint during the inversion process yields impressive stability and accuracy. Additionally the method exhibits a remarkable ability to image and identify point like dipole sources even when spaced closer than a fraction of the wavelength from each other. The proposed inversion procedure is very simple to implement, is easily adaptable to arbitrary surfaces, and is relatively fast even with dense grids. These features make the proposed method suitable for a complete on-the-spot electromagnetic radiation analysis; a capability in which many applications rely on. Proof of concept for this work is established through simple numerical experiments, and from physical measurements taken for a slotted radiating cylinder. [ABSTRACT FROM PUBLISHER]

In this paper, we propose a novel electrically small dual-band reconfigurable antenna. By using a compact eighth-mode substrate integrated waveguide (EMSIW) structure, we designed a compact antenna. This antenna is capable of dual-band operation by additionally loading an electrically small complementary split-ring resonator (CSRR) structure. The EMSIW and CSRR structures are designed for satisfactory operations at bandwidths of 1.575 GHz [global positioning system (GPS)] and 2.4 GHz [wireless local area network (WLAN)], respectively. We load the CSRR with a varactor diode to achieve a narrow bandwidth and to enable the resonant frequency to continuously vary from 2.4 GHz to 2.5 GHz. Thus, we realize a channel selection function, which is used according to WLAN standards. Irrespective of the variation in the varactor diode voltage, the resonant frequency of the EMSIW is not varied, such that the antenna maintains a constant frequency at the GPS bandwidth even at different voltages. Consequently, as the DC bias voltage varies from 11.4 V to 30 V, the resonant frequency at the WLAN bandwidth continuously varies between 2.38 GHz and 2.5 GHz. We observe that the simulated and measured s-parameter values and radiation patterns are in good agreement with each other. [ABSTRACT FROM PUBLISHER]

In this paper, we present a wireless power transfer (WPT) that is adaptive to change in coil separation. For analytic design of the WPT system, a new design method which does not require calculating the voltages and currents in the system is presented. The proposed design method allows us to have perfect impedance matching theoretically for the WPT system using capacitor circuits connected to the sending and receiving coils. Closed-form design equations are provided for straight-forward application of the new design method. In order to compensate the variation of the mutual coupling between the two coils due to the change in separation, we propose a new switchable capacitor array circuit. For verification of the new design method and the new switchable capacitor array circuit, we have fabricated and measured a WPT system operating at 370 kHz. Measured results have shown a good agreement with theoretical responses, and the reflected power ratio smaller than 3% has been achieved by using the proposed switchable capacitor array circuit over the 5:1 change of coil separation. [ABSTRACT FROM PUBLISHER]

This paper investigates the impact of the DUT antenna pattern on the test area performance for multi-probe based MIMO OTA setup in terms of received voltage and spatial correlation. The plane wave synthesis (PWS) technique has been proposed for vertical polarization in the literature, where the goal is to approximate plane waves with arbitrary directions. The received voltage at the antenna terminal depends on the antenna radiation pattern and the impinging plane waves. A novel closed form technique to reproduce the received voltage with arbitrary incoming plane waves based on trigonometric interpolation is presented. The proposed technique provides a closed form solution for the PWS when the probe ring radius is infinite. The proposed technique shows that the impact of the antenna pattern on the induced received voltage accuracy is ruled by Nyquist sampling theory. Furthermore, the impact of the antenna pattern on spatial correlation accuracy for prefaded signal synthesis (PFS) technique is investigated as well. Simulation and measurement results show that the number of required probes depend directly on the DUT antenna pattern. To test realistic DUTs with higher variations in directivity, we need more probes to maintain the same received voltage and spatial correlation accuracy level. [ABSTRACT FROM PUBLISHER]

A new technique is introduced for evaluating the vector potential of circular loop antennas (CLAs) with arbitrary current distribution and dimensions, which can be used to obtain the exact electromagnetic fields in near and far regions of the antenna. The technique is based on the spherical Bessel functions (SBFs) and associated Legendre polynomials (ALPs) expansion. This expansion is used to decouple the azimuth variables of the integrand of the vector potential integrals from the other variables in a separate functions that depend exponentially on azimuth variables. This technique reduces greatly the mathematical operations for evaluation of the vector potential to only one simple integration. The technique is used to obtain exact electromagnetic fields expressions for a thin-wire CLA of arbitrary current distribution and dimension, which is valid everywhere except on the loop. The well known far-fields for the CLA of arbitrary current distribution as well as near and far-fields for uniform current loop and small loop are obtained from the general field expressions presented in this paper as an special cases. [ABSTRACT FROM PUBLISHER]

Fully numerical schemes are presented for high precision computations of the four-dimensional integrals arising in Galerkin surface integral equation formulations. More specifically, the focal point of this paper is the singular integrals for coincident, edge adjacent and vertex adjacent planar and curvilinear triangular elements. The proposed method, dubbed as DIRECTFN, utilizes a series of variable transformations, able to cancel both weak (1/R) and strong (1/R^2) singularities. In addition, appropriate interchanges in the order of the associated one-dimensional integrations result in further regularization of the overall integrals. The final integrands are analytic functions with respect to all variables involved and, hence, the integrals can be efficiently evaluated by means of simple Gaussian integration. The accuracy and convergence properties of the new schemes are demonstrated by evaluating representative weakly singular and strongly singular integrals over planar and quadratic curvilinear elements. [ABSTRACT FROM PUBLISHER]

The physical channels establishing intrabody communications were first treated as capacitive circuits by Zimmerman. In Zimmerman's model, the human body is approximated as a perfect conductor. The equivalent-circuit parameters of the perfect conductor models can be strictly obtained based on electrostatic analyses; however, the perfect conductor models cannot be applied if conduction currents inside the human body are not negligible. In the present paper, a theory of the equivalent circuit for lossy conductors is described, and the physical mechanism of the communication channels inducing conduction currents inside the human body is addressed. [ABSTRACT FROM PUBLISHER]

This paper deals with the prediction of the effects of surface distortion on the radiation characteristics of arrays of slot antennas. The deformation of an object caused by exterior loads is calculated by a finite element method. The coupled structural electromagnetic (CSE) model of slotted waveguide arrays (SWA) is developed by the analysis of the positional difference of radiating slots in the aperture field caused by structural displacement. The slot voltages in this model are either obtained from finite-element simulations or by near-field measurements. Then the far fields can be calculated according to the coupled model. Two prototype antennas were manufactured and measured, and their deformation accomplished by a specific device with some fixed points and forcing points. Finally, measurements and simulation results are presented for the two prototypes. [ABSTRACT FROM AUTHOR]

The compound interferometer is a well-known multiplicative receiving array. This paper shows that its product pattern can be made equal to the power pattern of a conventional linear array with uniform element weighting. Moreover, the compound interferometer has fewer elements, effectively a thinned array. The thinning factor improves as the size of the arrays increases. It is also shown that the method can be extended to planar arrays with very significant thinning as the array size increases. [ABSTRACT FROM AUTHOR]

In this paper, we present an enlarged cell technique (ECT) to avoid the time step reduction encountered in the conformal finite-difference time-domain (CFDTD) method due to small irregular cells truncated by metallic boundaries. We focus our efforts on the discussion of the accuracy and stability of the ECT and its comparison with other conformal methods, especially the one called the uniformly stable conformal (USC) method. We also provide a simplified ECT, which is much easier to implement. In the ECT, a stability criterion is first constructed to identify instable irregular cells, i.e., those having so small an area to cause instability. Those instable cells are then enlarged into their adjacent cells to obtain a large, stable area. Careful treatment is performed on the communication between the intruding and intruded cells in terms of electromotive force by keeping the total electromotive force conservative. This technique is verified by several 3-D numerical experiments. Results show that the ECT is second-order accurate and numerically stable at the regular Courant time step limit. [ABSTRACT FROM AUTHOR]

The recently proposed theory of Maxwellian circuits is demonstrated for applications to linear wire scatterers as well as to linear antennas. It is shown that for each integral equation of thin wire type, there exist coupled linear ordinary differential equations of currents and voltages, the solutions of which are identical to the integral equation, if the same boundary conditions of the integral equation are applied. The subsequence is that the coupled differential equations can be interpreted as equivalent circuit of new type named Maxwellian circuit. The equivalent circuit can provide physical insights to design engineers and computational advantages for broadband calculations. The highlight of this paper is to show both theoretically and numerically that the Maxwellian circuit components depend only on the geometry of the problem, not on the excitation or boundary conditions at the terminals. [ABSTRACT FROM AUTHOR]

The author would like to thank the commentators, Dr. Zheng and Dr. Li, for reviewing and commenting on the work reported in refid="ref1"/. The author disagrees with their conclusion that the author in refid="ref1"/ is “criticizing the merits” of their published papers. The author is merely explaining the differences between the author's work in refid="ref1"/ and the commentators' work reported in refid="ref2"/. This should not detract from the contribution they made in refid="ref2"/ as indicated in their comments. [ABSTRACT FROM PUBLISHER]