PMC Boundary Research Articles

Low bandwidth chipless RFID tag using complementary split ring resonator

A small structure for chipless RFID tag is proposed; it is inspired by a C-shaped structure and based on HCSRR. This structure has curved strips, which are obtained by fine cutting the substrate from the symmetry of the C-shaped structure as base structure, and then missing part of the path is compensated by creating the PMC boundary condition in the cut-off point according to the image theory. Hence, the resonant frequencies of the proposed structure remain the same as those of the base structure. The substrate is Rog4003 with ϵr =3.55 and dimensions of 30×15×0.8 mm3, the ratio of area to lambda for the first resonant in 2.4 GHz is 0.073, and the average distance between two resonances is 300 MHz Half the structure without adding any other element reduces the production cost by 50%. Moreover, the structure can be printed on flexible substrates due to its simple design and non-complexity.

Compact Ultrawideband Antenna on Folded Ground Plane

A compact ultrawideband antenna on folded ground plane is proposed, which is a compact and low-profile structure. The proposed antenna mimics the operation of a unit element of the tightly coupled dipole array (TCDA) with modified boundary condition. The antenna does not have the PMC boundary required by the original TCDA, which makes the implementation and the impedance matching of the proposed antenna easy. All the design procedures are explained and confirmed by the EM simulation. The measured results show that the impedance bandwidth (IBW) is 0.72–3.43 GHz (130.6%) for the VSWR $\kappa \alpha $ ) of 0.82 at the lowest operating frequency and an overall dimension of $0.17\lambda _{\mathrm {low}} \times 0.17\lambda _{\mathrm {low}} \times 0.11\lambda _{\mathrm {low}}$ in terms of the wavelength at the lowest operating wavelength.

Exact Solution for the Protected TEM Edge Mode in a PTD-Symmetric Parallel-Plate Waveguide

A Parity Time-reversal Dual (PTD) symmetric structure constituted by a Perfectly-Electric-Perfectly magnetic (PEC-PMC) parallel plate waveguide (PPW) is analyzed. This waveguide supports unimodal transverse electromagnetic (TEM) edge mode propagation protected against back-scattering from a certain class of deformations and defects. The TEM solution is found in analytical form by using three different methods, namely conformal mapping, mode-matching, and Fourier-transform methods. It is shown through numerical simulations that the mode propagation is robust with respect to deformations such as 90{\deg} bends and discontinuity such as transition to free-space. Implementation of the PMC boundary conditions via both a bed of nails and a mushroom structure is also successfully investigated.

Generalized Soft-and-Hard/DB Boundary

A novel class of boundary conditions is introduced as a generalization of the previously defined class of soft-and-hard/DB (SHDB) boundary conditions. It is shown that the conditions for the generalized soft-and-hard/DB (GSHDB) boundary arise most naturally in a simple and straightforward manner by applying four-dimensional differential-form and dyadic formalism. At a given boundary surface, the GSHDB conditions are governed by two one-forms. In terms of Gibbsian 3D vector and dyadic algebra the GSHDB conditions are defined in terms of two vectors tangential to the boundary surface and two scalars. Considering plane-wave reflection from the GSHDB boundary, for two eigenpolarizations, the GSHDB boundary can be replaced by the PEC or PMC boundary. Special attention is paid to the problem of plane waves matched to the GSHDB boundary, defined by a 2D dispersion equation for the wave vector, making the reflection dyadic indeterminate. Examples of dispersion curves for various chosen parameters of the GSHDB boundary are given. Conditions for a possible medium whose interface acts as a GSHDB boundary are discussed.

PEC-PMC Baffle Inside Circular Cross Section Waveguide for Reduction of Cut-Off Frequency

A design and position of a baffle placed inside a circular waveguide is presented which leads to the lowest possible cutoff frequency. The reduction in the cutoff frequency is achieved by having one side of the baffle be PEC while the other is PMC. The introduction of PMC boundary conditions leads to unique eigenvalues for the dominant mode resulting in 66% reduction in the cutoff frequency compared to that of a circular waveguide with a baffle with PEC surfaces on both sides and 41.7% reduction in the cutoff frequency compared to that of an empty waveguide. An $e^{j\omega t}$ time convention is used.

ELECTROMAGNETIC BOUNDARIES WITH PEC/PMC EQUIVALENCE

The most general electromagnetic boundary, deflned by linear and local boundary conditions, is deflned in terms of conditions which can be called generalized impedance boundary conditions. Requiring that the boundary be equivalent to PEC and PMC boundaries for its two eigen- plane waves, which property is known to exist for many of its special cases, it is shown that the recently introduced Generalized Soft-and-Hard/DB (GSHDB) boundary is the most general boundary satisfying this property.

하이브리드 방법을 이용한 다층 미앤더선로 구조의 3:1 광대역 원편파 편파기 설계

Abstract In this paper, a wideband circular polarizer operating in the frequency range of 6<18 GHz is designed and fabricated using a multilayer structure with meanderlines. A T matrix expression for the unit structure, which consists of meanderline, dielectric substrate and spacer, was derived using the boundary value solution. A proposed meanderline structure was modeled as an array of unit meanderline cell in order to apply the waveguide model with PEC and PMC boundary conditions. The calculation procedures to obtain an equivalent susceptance of the unit meanderline cell using HFSS was also suggested. Using a hybrid method, which combines the T matrix with the HFSS results, and cut-and-try method, a wideband circular polarizer with low insertion loss and good AR performance was designed. The fabricated polarizer has the return loss less than 10 dB within 92 % bandwidth, the average insertion loss less than 0.24 dB, and the average AR below 2.6 dB for full 3:1 bandwidth. Key words: Wideband Circular Polarizer, Meanderline „in oCS(Agency for Defense Development) *†‡ ˆ ‰ n(Department of Radio Science & Engineering, Chung-Nam National University) 8Manuscript received July 31, 2015 ; Revised August 26, 2015 ; Accepted August 26, 2015. (ID No. 20150731-053)8Corresponding Author: Jeong-Ki Pack (e-mail: jkpack@cnu.ac.kr)

BROADBAND GREEN'S FUNCTION WITH LOW WAVENUMBER EXTRACTION FOR ARBITRARY SHAPED WAVEGUIDE AND APPLICATIONS TO MODELING OF VIAS IN FINITE POWER/GROUND PLANE

In this paper we developed the method of broadband Green's function with low wavenumber extraction (BBGFL) for arbitrary shaped waveguide. The case of Neumann boundary condition is treated. The BBGFL has the advantage that when using it to solve boundary value problems in a waveguide, the boundary conditions have been satisfied already. The broadband Green's function is expressed in modal expansion of modes that are frequency independent. To accelerate the convergence of the Green's function, a low wavenumber extraction is performed. The singularity of the Green's function is also extracted by such low wavenumber extraction. Numerical results show that BBGLF and direct MoM are in good agreement. We next illustrate the application of BBGFL for broadband simulations of vias in printed circuit boards (PCB) by combining with the method of Foldy-Lax multiple scattering equation. The results show that BBGFL are in good agreement with MoM and HFSS. It is also shown that BBGFL is many times faster than direct MoM and HFSS. The computational efficiency in broadband simulations makes this technique useful for fast computer-aided design (CAD). The effects of waveguide or cavity structures are critical for the electrical performance of electronic devices and components in signal integrity (SI), power integrity (PI), electromagnetic interference (EMI), and electromagnetic compatibility (EMC). Harmful electromagnetic signal noises or interferences are often generated and amplified at the resonant frequencies of the waveguide or cavity structures. The issues deteriorate when the electronic devices or computer systems operate at higher frequency or faster speed. In printed circuited boards (PCBs), two adjacent power/ground planes form a waveguide/cavity structure. The propagating modes satisfy the PMC (Neumann boundary conditions) at the edges of PCB power/ground plane structures. The power/ground plane structures are the key root causes in SI/PI and EMI/EMC problems. Vias are used for vertical interconnects for multilayer PCBs. At frequencies near the resonant frequencies, the propagating electromagnetic waves excite resonant modes, that result in strong edge radiations. These cause EMI/EMC problems. The switching noises induced by voltage regulator module (VRM) generate voltage fluctuations and lead to PI problems. The high frequency power noise can also couple into signal vias and cause SI/PI coupling issues. Therefore, the modeling of PCB cavity with vias is critical in practical designs and applications of high speed PCBs and packages. Fast and accurate modeling technique is desired for broadband simulations in electronic design and application. The finiteness of the parallel power/ground planes make them waveguide/cavity structures. The power/ground planes are also of arbitrary shape. Commercial tools such as HFSS provide solutions for the analysis of the via-cavity coupling problem. The tools require large CPU and memory and are not suited for broadband analysis. The physical problem is that of TM modes in a cavity with PMC boundary conditions on the side walls. Various methods have been used for waveguide

Dispersion Curves and Fields for a Chiral Negative Refraction Parallel-Plate Waveguide under PMC Boundary

The characteristics of a chiral negative refraction parallel-plate waveguide under PMC boundary are studied theoretically, and the corresponding dispersion relations, cut-off frequencies, propagating guided modes are obtained. Some novel features are found, such as fundamental mode will be not exist only if the chirality parameter κ&gt;1, in addition, the cutoff frequency is no longer the conventionally defined frequency when propagation constant is zero, but the least frequency that guided mode can still propagate. According to the relations between propagation constant β and wavenumbers k+,k-, the dispersion curves are divided into three regions , and the electromagnetic field components in the regions are analyzed in detail.

Achieving PMC boundary conditions through metamaterials

Purpose– The purpose of this paper is to show how metamaterials with extreme values of permittivity and permeability, may be effectively used to design artificial magnetic conductors (AMC) at a given frequency. In particular, this paper theoretically determines, for the different polarizations of the incidence field, the conditions under which metamaterials can behave as an AMC.Design/methodology/approach– In order to find out the required values of the constitutive parameters, this paper has done a theoretical analysis based on the transmission-line theory. The obtained analytical reflection coefficient has been particularized for the different possible polarizations of the incidence field in order to find the constitutive parameters values that this paper needs for the AMC behavior.Findings– Depending on the polarization of the field, it is shown that different values of the constitutive parameters are needed to get AMCs. In particular, it is shown that in the case of TEM and TE polarizations, a large value of the permeability is enough to obtain an AMC boundary condition. In the case of the TM polarization, instead, the AMC boundary condition is effectively achieved by using a material with vanishing permittivity. The role of the permittivity in the three polarizations is discussed. Finally, possible implementations and applications at microwave and optical frequencies are presented.Originality/value– The idea of using miniaturized inclusions to obtain AMCs is not completely new. However, to the authors' best knowledge, a complete and rigorous theoretical analysis showing the capabilities and the limits of this approach has not yet been presented in the open technical literature.

Soft-and-Hard/DB Boundary Conditions Defined by a Skewon-Axion Medium

A novel set of electromagnetic boundary conditions is defined in terms of an interface of a medium belonging to the class of skewon-axion media. Such a medium class can be introduced in a simple and natural manner applying four-dimensional representation of electromagnetic media. It is shown that the novel boundary conditions generalize soft-and-hard (SH) and DB boundary conditions to SHDB conditions. As an application, reflection of a plane wave from a planar SHDB boundary is studied. It is shown that the two eigenvectors of the reflection dyadic define eigenwaves for which the SHDB boundary can be replaced by equivalent PEC or PMC boundaries. The theory is tested with numerical examples which reveal an interesting narrow-beamed reflection phenomenon associated to the SHDB boundary condition.

Reflection From Stratified Media Backed by a Perfect Electromagnetic Conductor (PEMC)

Perfect electromagnetic conducting (PEMC) boundary is a generalization of both PEC and PMC boundaries, creating nonreciprocal reflection which could be cross-polarized with respect to the incident wave. In this communication, reflection from a stratified medium, backed by a PEMC boundary due to an oblique incident plane wave is calculated analytically. In general, the medium is considered as N layers of frequency dispersive bianisotropic media. Applying the PEMC boundary condition, the reflection dyadic is computed using the notion of propagators and wave-splitting technique. The method is validated through deriving the reflection dyadics of a plane wave from 1) PEC-backed stratified medium and 2) a PEMC-free space interface whose analytical expressions exist. Furthermore, few numerical examples illustrating the method as well as its applications are provided.

On the energy flux through a uniaxial chiral metamaterial made circular waveguide under PMC boundary

Propagation of electromagnetic waves through a circular waveguide consisting of uniaxial anisotropic chiral metamaterial is studied. The outer surface of the guide is assumed to be coated with a perfect magnetic conductor material. The characteristic eigenvalue equation corresponding to the guided modes is deduced followed by the investigation of the cut-off frequencies and the flow of energy flux considering three different kinds of uniaxial chiral metamaterials. The propagation of negative energy flux through the metamaterial medium is found, which leads toward the phenomenon of backward waves in uniaxial anisotropic chiral mediums. This feature is found to be greatly dependent on the type of the chiral material used in the waveguide medium.

Uniaxial IB-Medium Interface and Novel Boundary Conditions

The class of uniaxial electromagnetic IB media involving five medium parameters is defined as a special case of the previously defined class of general IB media (or skewon-axion media) involving 16 parameters. The problem of plane-wave reflection from and transmission through the interface of a uniaxial IB-medium half space is analyzed. It is shown that, for general values of the medium parameters, waves polarized TE and TM with respect to the normal direction are reflected as from the respective PEC and PMC boundaries. Unlike the anisotropic soft-and-hard surface which has a somewhat similar property, the uniaxial IB interface is isotropic in the plane of the interface. As a consequence, a novel class of electromagnetic boundaries can be defined for general fields requiring vanishing of the normal components of both D and B vectors at the boundary. Another realization of such a boundary in terms of an anisotropic metamaterial with zero axial permittivity and permeability is discussed.

Some Properties of Green's Functions of Waves At Boundaries

Some properties of Green's functions of waves at boundaries are presented in this paper. Of particular interest is their behaviour like Dirac delta distributions whose domain is the manifold of the boundary under consideration. We have obtained relations involving dyadic Green's functions for electromagnetic wave scattering problems with PEC, PMC and penetrable boundaries. Both isotropic and anisotropic homogeneous media are considered. Situations with multiple bodies with disjoint smooth boundaries are also part of our study. Some similar results for acoustic waves are given without proofs.