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This paper introduces compact Printed Ridge Gap Waveguide (PRGW) phase shifters tailored for millimeter-wave applications, with a focus on achieving wide operating bandwidth, and improved matching and phase balance compared to single-layer technology. This study proposes a unique approach to achieve the required phase shift in PRGW technology, which has not been previously explored. This study also introduces a novel analytical approach to calculate the cutoff frequency and propagation constant of the PRGW structure, a method not previously addressed. Furthermore, the utilization of multi-layer PRGW technology enables the realization of multi-layer beamforming networks without crossing, thereby supporting wideband operation in a compact size. The proposed design procedure enables the realization of various phase shift values ranging from 0 ∘ to 135 ∘ over a broad frequency bandwidth centered at 30 GHz. A 45-degree phase shifter is fabricated and tested, demonstrating a 10 GHz bandwidth (approximately 33% fractional bandwidth) from 25 GHz to 35 GHz. Throughout the operating bandwidth, the phase balance remains within 45 ± 5 ∘ , with a deep matching level of −20 dB. The proposed phase shifter exhibits desirable characteristics, such as compactness, low loss, and low dispersion, making it a suitable choice for millimeter-wave applications, including beyond 5G (B5G) and 6G wireless communications. [ABSTRACT FROM AUTHOR]

In this study, a traveling wave Mach-Zehnder intensity modulator (TW-MZM) was designed and optimized for six different electro-optical (EO) crystals: lithium niobate (LNB), potassium niobate (KNB), lithium titanate (LTO), beta barium borate (BBO), cadmium telluride (CdTe), and indium phosphide (InP). The performance of each EO crystal, including optical and radio frequency (RF) loss, applied voltage, and modulation bandwidth, was estimated and compared. The results suggest that, in theory, KNB, LTO, BBO, and CdTe have the potential to outperform LNB. However, it should be noted that the loss associated with KNB and LTO is comparable to that of LNB. The findings demonstrated that BBO and CdTe exhibit a modulation bandwidth exceeding 100 GHz and demonstrate the lowest loss among the considered crystals based on the assumed geometry. [ABSTRACT FROM AUTHOR]

Current physics is considered to be based on Newtonian mechanics. The existence of electromagnetic waves was demonstrated by the Maxwell equations. It is also possible to assume that the constitution of electromagnetic waves forms the fundamental principles of physics, including the composition of materials. To demonstrate this assumption, we introduced electromagnetic waves in coaxial cables and determined the propagation constant of these waves, as reported in this Session. The result showed that the real part of the propagation constant, known as the attenuation constant, can be set to zero. In this case, by expressing the variable of the electromagnetic waves as angular frequency («), it is possible to treat the variable of the function as an angle (in radians). As a consequence, we are able to introduce a mathematical representation of phase (neighborhood and metric) for electromagnetic waves. Thus, we demonstrate that the mathematical representation of electromagnetic waves is possible. [ABSTRACT FROM AUTHOR]

The present study reports a design procedure and numerical investigation of a photonic crystal fiber biosensor. The proposed sensor is consisting of irregular arranged rectangular holes. The core area has been arranged of a single rectangle for sensing the cancer cells and normal cells in the frequency range 1.0–2.5 THz. Zeonex has been utilized as a fiber material. The model has been organized and computationally investigated employing software based on the finite element method. The modeling of the designed sensor authenticates its capability in identifying cancer cells. An absorbing layer: perfectly matched layer has been used for calculating optical characteristics. It has been observed that the designed PCF sensor gives a high relative sensitivity of 81.38% for cancer cells and 65.83% for normal cells, respectively. Reduced confinement loss as 5.828 × 10−25 cm−1 has been achieved. Also, the effective area 2.549 × 10−8 µm2, birefringence 4.709 × 10−4, propagation constant 1.01961 × 10−24 and effective refractive index as 1.475 × 10−18 have been investigated. The present manufacturing technique is appropriate for the designing of proposed PCF sensor. [ABSTRACT FROM AUTHOR]

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A zeonex-based rectangular cored photonic crystal fiber sensor is designed and applied for investigating a number of optical properties for sensing alcohols of variant classes. The finite element method-based commercial software is utilized for numerical analyses. Five variant classes of alcohols namely methanol, ethanol, propanol, butanol, and pentanol are considered for the investigation. These analytes are injected into the rectangular core and the investigation is accomplished in the 1–2 THz regimes. The investigated results exhibit comparatively higher sensitivities of 93.3% for pentanol than the other alcohol variants. Besides, almost zero confinement loss profile is found for all the analytes just after 1.3 THz frequency. A trivial EML of 0.005 cm–1 is also attained from this simulation at 1.8 THz. Finally, the potentiality of this proposed sensor can be observed from the demonstration of different optical features like numerical aperture, effective area, core power fraction, and propagation constant. The anticipated sensor can achieve a larger sensitivity with negligible propagation losses at the same time. [ABSTRACT FROM AUTHOR]

This paper introduces compact Printed Ridge Gap Waveguide (PRGW) phase shifters tailored for millimeter-wave applications, with a focus on achieving wide operating bandwidth, and improved matching and phase balance compared to single-layer technology. This study proposes a unique approach to achieve the required phase shift in PRGW technology, which has not been previously explored. This study also introduces a novel analytical approach to calculate the cutoff frequency and propagation constant of the PRGW structure, a method not previously addressed. Furthermore, the utilization of multi-layer PRGW technology enables the realization of multi-layer beamforming networks without crossing, thereby supporting wideband operation in a compact size. The proposed design procedure enables the realization of various phase shift values ranging from 0∘ to 135∘ over a broad frequency bandwidth centered at 30 GHz. A 45-degree phase shifter is fabricated and tested, demonstrating a 10 GHz bandwidth (approximately 33% fractional bandwidth) from 25 GHz to 35 GHz. Throughout the operating bandwidth, the phase balance remains within 45 ± 5∘, with a deep matching level of −20 dB. The proposed phase shifter exhibits desirable characteristics, such as compactness, low loss, and low dispersion, making it a suitable choice for millimeter-wave applications, including beyond 5G (B5G) and 6G wireless communications.

In order to improve the vibration reduction performance of damping treatments, a new damping structure consisting of a uniform base layer and two periodically alternating free layers was examined in this study. Closed-form solutions for both the band structure and the forced response of the periodic bi-layer beam were theoretically derived and verified via numerical solutions using the finite-element method. The results showed that the structure with periodic free-layer damping (PFLD) treatment reduced broadband vibrations, and the levels of reduction were dominated by Bragg scattering in the band gaps and damping in the passbands. The vibration experiment verified the derived theory's accuracy and showed that the PFLD treatment could increase vibration reduction levels in low-frequency band gaps compared with traditional free-layer damping treatments. The effects of the parameters—cell lengths, sub-cell-length ratios, and thickness ratios—were also discussed, providing further understanding of the vibration reduction performance of the bi-layer beam with the PFLD treatment, and this can be used to help designers optimize the periodic bi-layer beam to achieve better performance. [ABSTRACT FROM AUTHOR]

This paper studies a 2‐D planar periodic leaky‐wave antenna based on a series of concentric annular microstrip rings on a grounded dielectric slab. The leaky wave is generated from the perturbation to the surface wave, which is excited from the fundamental and dominant TM0 mode. The computation method for the propagation constant is first analyzed, and then the radiation property is researched. A set of suitable structural parameters for only −1th spacial harmonic radiation are extracted from the theoretical computation and then verified by the simulation, which shows an agreement. The results indicate that this proposed antenna can radiate two symmetrical flat conical beams with over 90% total efficiency. The theoretical results on radiation performance are then verified by simulation and measurement with good agreement. [ABSTRACT FROM AUTHOR]

This study presents a new method for measuring the propagation constant of transmission lines using a single line standard and without prior calibration of a two-port vector network analyzer (VNA). The method provides accurate results by emulating multiple line standards of the multiline calibration method. Each line standard was realized by sweeping an unknown network along a transmission line. The network need not be symmetric or reciprocal, but must exhibit both transmission and reflection. We performed measurements using a slab coaxial airline and repeated the measurements on three different VNAs. The measured propagation constant of the slab coaxial airline from all VNAs was nearly identical. By avoiding disconnecting or moving the cables, the proposed method eliminates errors related to the repeatability of connectors, resulting in improved broadband traceability to SI units. [ABSTRACT FROM AUTHOR]

This paper presents a material relative permittivity extraction technique based on three measurements of two identical coaxial lines, terminated by a short-circuit configuration. The test cells have the same geometric dimensions but various lengths. The most extended fixture is partially filled with the sample under test to be measured in the scanned frequency [6–20] GHz. The measurement methodology is based on the use of the fixture form factor. The accuracy of the relative permittivity parameter is better than 5% throughout the frequency range. All tested samples have been compared with the two transmission-line technique results. [ABSTRACT FROM AUTHOR]

Many quantum technologies rely heavily on propagation of RF and microwave signals through devices at cryogenic temperatures, and detailed understanding of materials and signal propagation is therefore key to improving the performance of quantum circuits. The properties of dielectric substrate materials used for transmission lines (TLs) such as their permittivity need to be precisely determined to design high performance quantum integrated circuits. In this paper, we discuss a measurement technique for determining the effective permittivity of a TL at mK temperatures. The technique utilizes S-parameter measurements of multiple TLs to reliably extract the effective permittivity of the TL implemented in a substrate material. The technique is demonstrated using measured S-parameters of grounded co-planar waveguide (GCPW) at 296 K and 15 mK. The effective permittivity of the TL at 296 K and 15 mK are determined from measurements and compared. We observed the effective permittivity determinations at 15 mK to be approximately frequency independent and calculated the relative permittivity of Rogers RO4350B material at 15 mK to be 3.64. There is no significant deviation from this relative permittivity value with respect to manufacturer data and from measured data at 296 K.

This work encompasses some relevant issues that arise when using a broadband method to characterize the even and odd mode propagation constants of symmetric microstrip coupled lines using four-port pure-mode differential and common mode S-Parameters. Correct excitations of differential and common modes play a significant role in experimental results. From these 4-port measurements, parameters corresponding to the even and odd modes can be extracted from the multi-mode generalized S-parameters obtained by the vector network analyzer. Differential and common mode sub-matrices are considered as two independent equivalent 2-port transmission lines. The method will be applied to extract the propagation constants of even and odd modes of coupled microstrip transmission lines. A discussion is included on ensuring the correct excitation of the modes in the structure and avoiding possible unwanted effects such as radiation, that negatively affects the final estimation, both in phase and attenuation. Two figures of merit are defined to evaluate how transitions affect the performance of the method. These figures of merit allow a reasonable estimation of how the final experiment is affected by selected excitation of modes. To assess the theory presented, two sets of seven lines of different lengths are manufactured. The experimental results show an excellent agreement, both with electromagnetic simulations and with the analytical model used, for the phase constant in the improved case of 30° bends, and an improvement in the useful bandwidth of the attenuation constant. This fact verifies the correct functioning of the method. In addition, the measurements are presented in the range of 0.01–67 GHz, which represents a significant advance in bandwidth for this type of structure.

The paper focuses on the problem of transverse electric wave propagation in a plane-shielded waveguide filled with a nonhomogeneous and nonlinear (Kerr) medium. The nonlinear part of the permittivity is characterized by the Kerr law in the focusing regime, while its linear part is a constant that is perturbed by a small continuous function. Such perturbation can be considered to be an attempt to take into account the inevitable presence of impurities in the medium, causing slight deviations in the dielectric permittivity. In the paper, the existence of solutions to the considered problem is proved, including solutions with and without linear counterparts. Some numerical results are presented as well. [ABSTRACT FROM AUTHOR]

An electromagnetic transient study has been performed based on a practical 500 kV mixed transmission system. The system has overhead lines, submarine cables and underground cables. An exact expression of earth-return impedance for submarine cable has been developed. A new equivalent homogeneous earth method (EHEM) is also proposed based on the exact formula. The influences of air, seawater, seabed, wired armor structure and multi-layer seabed on series impedance and modal propagation constants of submarine cable are investigated. A novel modeling procedure on parametrical side of mixed transmission system is proposed in this paper. Moreover, the input sequence impedances of mixed transmission system are studied based on traditional Line / Cable Constant routines and the new method. Transient simulations are also performed using classical and new methods. The results are further validated with recently proposed MoM-SO technique. [ABSTRACT FROM AUTHOR]

This paper describes a material complex permittivity extraction technique based on four measurements of two identical coaxial (circular and rectangular) lines, distinguished by their lengths. The paper presents a combination of propagation parameters through mixing the eigenvalue principle and the lines' characteristic impedance to improve the extraction techniques of intrinsic material parameters. However, the accuracy of some material parameters is insufficient, as the discontinuities at the feedline–ideal line interface are not adequately solved. In these cases, a new formulation of the complex effective permittivity is suggested, associating the propagation constant and the characteristic impedance for a homogeneous structure. Next, uncertain errors that can negatively impact the method are removed from the mathematical expression. Then, a characteristic impedance expression is developed in the second stage to improve the mathematical formulation. Finally, a correction coefficient in tune with reality and a polynomial function to amend the behavior of some of the curves are provided. The approach's novelty lies in its ability to extract and correct the characteristic impedances despite discontinuity impedances at the ideal line–feedline interface. Several materials are tested with circular and/or rectangular coaxial fixtures to confirm the performance of the suggested method. The test cells are homogeneous, full, and long, at 80 mm and 100 mm (50 mm for the circular one). Determining the propagation constant from the eigenvalue of the wave cascading matrix (WCM) is a fundamental step in this method. Knowing the propagation constant helps to automatically compute a correction coefficient that depends on the fixture and the material being tested. Experimental validation is performed in the frequency range from some MHz to 10 GHz, 13.5 GHz, and 20 GHz, according to the tested material. Both test fixtures are filled with the sample material, with a vacuum considered as a reference parameter. The method's accuracy is better than 5% on the relative permittivity parameter throughout the frequency range. All the tested samples are compared with the results using the filled two-transmission-line technique (FTTL), using only the eigenvalue determination principle. The trapper cells are coaxially circular and rectangular. [ABSTRACT FROM AUTHOR]

Pipe systems are commonly used in the process and power industries to transport fluid from one terminal to others. Propagation behaviour of lateral flexural waves in a pipe coupled with periodic rack structure is investigated. The pipe-rack system considered in this study is a practical case and is realized as a pipe on periodic elastic supports, while a pipe on simple and without supports represents special cases when the rack stiffness leads to extreme values. The propagation constant relations in terms of frequency are derived using Bloch–Floquet theorem which are successively verified with finite element models. The results show that a pipe with rack creates a narrow locally resonant band gap in low-frequency range which is caused by the first natural mode of the rack. Conversely, a pipe on simple supports entails only Bragg-type band gaps, while a pipe without supports carries no band gap. For tuning the band gap properties, a two-degrees-of-freedom lateral localized resonator is attached to the centre of each unit cell of the pipe. It is found that certain frequency ranges in the targeted pass bands are effectively controlled by the resonator. Furthermore, the effect of various resonator parameters, i.e. mass ratio, stiffness and damping, on band gaps is examined. It is observed that the band gaps are vanished when damping is introduced in the system. The results show a promising way to flexural vibration control of a periodic piping system with various boundary conditions. [ABSTRACT FROM AUTHOR]

In order to improve the vibration reduction performance of damping treatments, a new damping structure consisting of a uniform base layer and two periodically alternating free layers was examined in this study. Closed-form solutions for both the band structure and the forced response of the periodic bi-layer beam were theoretically derived and verified via numerical solutions using the finite-element method. The results showed that the structure with periodic free-layer damping (PFLD) treatment reduced broadband vibrations, and the levels of reduction were dominated by Bragg scattering in the band gaps and damping in the passbands. The vibration experiment verified the derived theory’s accuracy and showed that the PFLD treatment could increase vibration reduction levels in low-frequency band gaps compared with traditional free-layer damping treatments. The effects of the parameters—cell lengths, sub-cell-length ratios, and thickness ratios—were also discussed, providing further understanding of the vibration reduction performance of the bi-layer beam with the PFLD treatment, and this can be used to help designers optimize the periodic bi-layer beam to achieve better performance.

After further transmission line technique investigation, we propose a new approach to material characterization based on the combination of the propagation constant and the characteristic impedance of the transmission-line. Three main elements constitute the approach novelty’s root: the determination of the propagation constant without using the eigenvalue principle, the improved mathematical expression of the characteristic impedance, and the automatically corrected coefficient. The two-line technique is based on three required measures, where the most extended fixture is partially filled with the specimen to be tested. As a result, the discontinuities caused by the geometric change of access interfaces and the waveguide dimensions have been solved. The characteristic impedance is determined straight and amended by a third polynomial function degree. The polynomial function and the amended correction coefficient determination are the facilitation parameters of the new approach technique. This new method allows the extraction of the material’s complex relative permittivity. The procedure has been validated with the Rogers RO4003C, Alumina 99.6%, and Vinifera (based on the dielectric materials available in our laboratory) through the microstrip fixture in the scanned frequency (0.08–8) GHz by extracting its electric intrinsic parameters. The dielectric constants range from 1.1–10.4, where the thicknesses are 1.54 mm, 2.067 mm, and 1.078 mm have been used. Two identical microstrip test cells with the same geometric dimensions but various lengths have been manufactured. That promotes the feasibility of two measures simultaneously.

Cherenkov radiation emitted by Kuznetsov–Ma soliton (KMS) with an arbitrary propagation constant in the presence of higher-order dispersions is studied analytically and numerically. We show that the third-order dispersion (TOD) yields asymmetric radiated bands, while the fourth-order dispersion (FOD) gives rise to symmetric radiated bands only when the value of FOD is positive. In contrast to radiations emitted by other localized waves, such a radiation emerges periodically in propagation, and can exhibit multi-frequency bands which depends strongly on the propagation constant of the KMS. We presented radiation conditions to calculate different frequency bands, which shows great agreement with numerical simulations. Important radiation features such as radiation frequencies, velocities, and distances are shown in phase diagrams. Our results could be helpful for controllable radiations in nonlinear fiber and other nonlinear systems.

This article presents a 325–500 GHz single-layer planar Goubau-line antenna with endfire radiation based on substrate mode. The electromagnetic (EM) fields along the Goubau line will penetrate into the substrate due to the substrate modes, which cannot operate well compared with the conventional transmission line. The undesired $E_{\text{z}}^{11}$ substrate mode is engineered here to achieve vertically polarized endfire radiation. Since the higher substrate mode is excited and there is a deviation between the propagation constants of the Goubau line and the $E_{\text{z}}^{11} $ substrate mode, the phase difference between the center and edges of the truncated aperture will deteriorate the antenna radiation at higher frequencies. Inspired by the conventional Goubau-line divider, the branches can compensate the wavefront and increase the antenna gain by 2 dB at higher frequencies. This terahertz (THz) antenna on a 300 $\mu \text{m}$ thick quartz substrate ($0.4~\lambda _{0}$ at 400 GHz) possesses robust mechanical properties and consists of single-layer metal, reducing the fabrication complexity. The proposed THz antenna was fabricated and measured, which can operate in a 325–500 GHz band with endfire radiation and achieve 8.5–11.3 dBi gain. [ABSTRACT FROM AUTHOR]

A circularly-polarized (CP) traveling-wave endfire antenna featuring low profile, high gain, and simple feeding structure is presented in this communication. Offset parallel strips with proper dielectric loading are employed in a low-profile substrate to achieve two orthogonal electric field components with equal magnitude and 90° phase difference for CP endfire radiation. Meanwhile, periodic phase-loading technique is used to achieve a proper phase constant for high endfire gain. A prototype is designed and fabricated to verify the proposed method. Experimental results demonstrate CP endfire radiation within a frequency band of 9.78–10.09 GHz. The average endfire gain is 10.3 dBic with an average efficiency of 62.5%. [ABSTRACT FROM AUTHOR]

Wideband permittivity and loss tangent curves for the dielectric laminate of a printed circuit board are obtained. For this purpose, the single-frequency data provided by the laminate manufacturer together with propagation constant experimentally obtained from stripline measurements are used. This allows for enabling the wideband simulation of interconnects while the dielectric material properties are defined respecting causality. Furthermore, using the extracted data, the dielectric and conductor effects on the signal attenuation and delay can be separated to analyze the corresponding impact on the propagation features of interconnects. This is demonstrated here through the implementation of an RLGC model up to 30 GHz. [ABSTRACT FROM AUTHOR]

Simple methods using a microstrip coupled-line directional coupler (CLDC) are presented for dielectric constant measurements. The material under test (MUT) is placed on the coupled-line section of the coupler, and either the coupler’s coupling ($\lvert S_{31} \lvert $) or its isolation level ($\lvert S_{41} \lvert $) is considered as the sensor’s response. Putting different MUTs on the microstrip line leads to a change in the effective dielectric constant of the structure and consequently causing a change in the coupling coefficient. In addition, since the isolation level of a microstrip coupled-line coupler depends on the phase velocity difference between the substrate and the medium above the signal strips, putting different MUTs on the line significantly changes the isolation level. This change is significantly greater than the change in $\lvert S_{21} \lvert $ level of a microstrip line when loaded with different MUTs. Validation of the method is presented through measurements for both solid and liquid MUTs. [ABSTRACT FROM AUTHOR]

In this article, a step-sized Substrate Integrated Waveguide (SIW) is designed, simulated, and a prototype is developed for performance validation. The various parameters of the SIW, like propagation constants, modal field distribution, etc., are analyzed and investigated. An antenna is designed and developed using the proposed SIW. The various important parameters of the designed stepped SIW antenna, such as return loss, total antenna gain, radiation pattern, radiation efficiency, etc., are determined and validated through experimental standers. The antenna is simulated using a commercially available finite element method-based high frequency structural simulator. The designed antenna shows the wideband frequency response from 6 GHz to 22 GHz in the simulating frequency range. The designed structure shows the various resonant frequencies. A minimum return loss of -39 dB is achieved at a frequency of 17 GHz. Overall, the gain of the antenna is high. The total maximum gain achieved by this antenna is around 12.5 dBi. The developed antenna offers high efficiency on the FR4 substrate. [ABSTRACT FROM AUTHOR]

This study presents a new method for measuring the propagation constant of transmission lines using a single line standard and without prior calibration of a two-port vector network analyzer (VNA). The method provides accurate results by emulating multiple line standards of the multiline calibration method. Each line standard was realized by sweeping an unknown network along a transmission line. The network need not be symmetric or reciprocal, but must exhibit both transmission and reflection. We performed measurements using a slab coaxial airline and repeated the measurements on three different VNAs. The measured propagation constant of the slab coaxial airline from all VNAs was nearly identical. By avoiding disconnecting or moving the cables, the proposed method eliminates errors related to the repeatability of connectors, resulting in improved broadband traceability to SI units.

A temperature-dependent modeling approach for interconnects is presented from 23 °C to 139 °C. To develop the proposal, the contribution of the conductor and the dielectric effects to the signal attenuation and delay is quantified from $S$ -parameters measured to edge-coupled transmission lines configured for differential signaling. Moreover, by obtaining the frequency and temperature-dependent complex permittivity of the dielectric and the characteristic impedance of the lines, a model and parameter extraction strategy for the RLGC parameters is proposed. This allows for a representation as a function of temperature and up to 12 GHz, which falls within the operation conditions of practical printed circuit boards based on glass fiber reinforced epoxy laminate materials. [ABSTRACT FROM AUTHOR]

In this letter, a periodic end-coupled leaky-wave antenna is designed based on an asymmetrically loading unit. A simple balancing condition in the equivalent distributed circuit model is developed for the open stopband suppression by introducing a complex effective resonant frequency. The proposed balancing condition naturally satisfies both the frequency-balancing condition and Q-balancing condition in the lumped circuit model. Based on the derived formula, the physical parameters could be quantitatively determined. Subsequently, two typical periodic end-coupled leaky-wave antennas are designed, implemented, and verified experimentally. The measured reflection coefficient and the radiation results show that the open stopband at the broadside frequency is successfully suppressed. [ABSTRACT FROM AUTHOR]

A microwave method is proposed to determine the forward and backward propagation constants ($\gamma ^{+}$ and $\gamma ^{-}$) and the wave impedance ($z_{w}$) of reciprocal and non-reciprocal microwave networks whose positions are not known within their measurement cells (position-insensitive). The proposed method relies purely on analytical expressions and can also evaluate the reference plane transformation distances. Scattering parameter measurements at the $X$ -band (8.2–12.4 GHz) of a reciprocal network (a waveguide straight) and a non-reciprocal network (a microwave phase shifter) arbitrarily positioned into their measurement cells were conducted to retrieve $\gamma ^{+}$ , $\gamma ^{-}$ , and $z_{w}$ for validation of our method and testing its position-insensitive property. The importance of the method becomes apparent when compared to conventional methods whose accuracy is based on precise determination of the reference planes. [ABSTRACT FROM AUTHOR]

The impedance matching equation of a single-layer dielectric-magnetic absorber excited by an oblique incidence plane wave is resolved with an expression providing the optimal thickness and highlighting the composite crucial parameters. The effective propagation constant of the nonuniform refracted plane wave into the absorber is represented by a new formulation as a function of the true refraction angle which is a real number unlike the complex quantity resulting from the Snell’s law, usually applied in the literature. The proposed design process is applied to compute microwave absorption performances of different dielectric-magnetic materials, considering both normal and oblique incidence. Furthermore, the incidence angle effect is investigated. [ABSTRACT FROM AUTHOR]

We propose a competitive approach for analysis and optimization of optical fiber performance. Taking into account the standard fiber fabrication cycle, we develop a model of highly multistepped optical fiber. We introduce a fast and accurate algorithm which allows one to obtain propagation constants and transverse fields for systems with thousands of steps within seconds. The approach relies on both the exact analytical formulation of the corresponding eigenvalue problem and an original solving algorithm of linear complexity with respect to the number of steps. The model accurately represents arbitrary smooth profiles with azimuthal symmetry, which, together with low computation time, opens up ample opportunities for various optimization schemes. Obtained results are compared with those of other numerical and analytical methods. [ABSTRACT FROM AUTHOR]

In this communication, the propagation equations of the electromagnetic waves in an inhomogeneous plasma column are solved, and the analytical estimation of the efficiency of the plasma antenna is presented. To validate the analytical results, an experimental prototype of a plasma monopole antenna is implemented while it is simulated using a commercial full-wave electromagnetic simulator. The implemented antenna can be excited by two different RF signals, at 450 and 1500 MHz, with a controllable power level between 1 and 50 W to adjust the effective length of the antenna. The proposed configuration allows both communication and excitation waves to be applied to a single coupling sleeve on the plasma column using a diplexer. Based on the measurement of the phase difference of two different positions along the column, using a phase difference detector microchip, the plasma density is estimated along the column. Good agreement between the results validates the proposed analytical method. The results show that the efficiency of a surface-wave-excited antenna strongly depends on the gas pressure, the excitation frequency, and the thickness of the tube. Therefore, for an optimized plasma antenna, all these parameters have to be properly used. [ABSTRACT FROM AUTHOR]

This communication presents the antenna gain pattern estimation from backscattering coefficient measurement performed within a reverberation chamber (RC). The antenna backscattering coefficient is measured for two load conditions, namely, an open circuit (OC) and a 50 $\Omega $ load, enabling to distinguish the radiation and structural modes from the total backscattered field. This approach is applied to the measurement of the gain pattern of a Vivaldi antenna at 6.5 GHz and compared with a conventional transmission-type measurement within an anechoic chamber (AC). The main lobe of the radiation pattern is in good agreement between both measurements. The difference between maximal gains, retrieved after a reference measurement using a metallic plate, is equal to 0.04 dB. A second validation is performed using a log-periodic antenna at 3.5 GHz, showing less than 0.76 dB difference over the measured angular range. To the best of our knowledge, this is the first time that a contactless gain pattern measurement is performed and validated within an RC. [ABSTRACT FROM AUTHOR]

A general method is presented for exciting discrete modes in waveguides of arbitrary geometry. Guided modes supported by the waveguide are first calculated using a finite difference frequency domain model. High efficiency holograms to excite these discrete modes are then generated using the Direct Search hologram generation algorithm. The Direct Search algorithm is optimised such that the inherent properties of waveguide modes are exploited to give faster execution times. A nodeless antiresonant photonic crystal fibre is considered as a test geometry, in which high-purity modes are experimentally excited and in-coupling efficiencies of up to 32.8% are obtained. [ABSTRACT FROM AUTHOR]

Medium voltage cables are poor transmitters of signals with high frequency spectrum such as partial discharges. The propagating signals are strongly attenuated and distorted depending on the transmitted distance. In order to understand this process, this article provides a model to simulate the transmission of such signals on medium voltage cables. Compared to earlier approaches, this model does not neglect the wave character of the high frequency signals. Therefore, to describe the signal transmission, a comprehensible solution of the telegrapher's equations is provided. To work with this solution, the propagation constant of the medium voltage cable used must also be known. This propagation constant is calculated on the basis of the individual cable layers, considering all ohmic and dielectric losses. In contrast to previous methods, all primary line constants are modeled frequency dependent. The final transmission model is able to predict the spectrum of a transmitted signal at any distance from its origin. Validation measurements show that prediction and measurement agree with good accuracy. A possible application of the developed model is the investigation of the transmission of partial discharges on medium voltage cables. This model is probably also suitable for high voltage cables. [ABSTRACT FROM AUTHOR]

A methodology to analyze the attenuation constant of surface wave propagating in general multilayer structures is proposed. The multilayer structure may include any number of layers, that can be made up of lossy dielectric, magnetic-material, and impedance surfaces. The non-linear characteristic equation (transverse resonance equation - TRE) that representing multilayer structure is defined by utilizing transmission line (TL) theory. Consequently, the root(s) of the TRE is/are computed which indicates the complex propagation constant of that characteristic equation. The obtained results are validated over the completely shielded waveguide structures where the full-wave simulation is possible. The proposed approach is employed to analyze and discuss the propagation and attenuation constant of surface wave modes in several representative examples. The analysis is carried out in the frequency range from 1 to 12 GHz.

In this article, a compact magnetic dipole (MD) composite right-/left-handed transmission line (CRLH-TL) leaky-wave antenna (LWA) is proposed, which is periodically loaded with rectangular gaps and short stubs. Then, in light of the dielectric resonator with a high dielectric constant, low loss tangent, and good radiation performance, we further add an alumina ceramic block (ACB) to stack on the gap in each CRLH-TL LWA unit cell for forming the MD, and thus, wide beam-scanning range and compactness are achieved. To validate this design, a traditional uniform CRLH-TL LWA is investigated in detail. The results of S-parameters, electrical field distribution, and radiation properties illuminate the effects of introducing the ACB, such as impendence matching improvement and high radiation efficiency. Furthermore, to verify the flexible control of the balanced condition and the attenuation constant by changing the microstrip gap width and the ACB thickness predicted in the circuit model analysis, a nonuniform CRLH-TL LWA with quasi-constant amplitude is fabricated. Experimental results demonstrate a higher antenna gain and the stability of wide beam-scanning range under the condition of a compact design. [ABSTRACT FROM AUTHOR]

In this article, an efficient domain decomposition method finite element method (DDM-FEM) algorithm is presented for the lossy twisted pair cable. In harsh environment and anti-interface ability, cables need high toughness, noise immunity, and extraordinary strength. We, in this paper, simulate a physical model of twisted pair cable and apply a hybrid solver of DDM-FEM to analyze these problems by compression and approximation of matrix-vector product. The DDMFEM solver along with matrix compression is used to compute the RLCG, propagation constant in the twisted pair cable, and to reduce the computational time and memory size. Therefore, in the proposed algorithm, the complexities of the system become linear. The study compares the calculated results with the existing standard to verify the effectiveness of the proposed algorithm. [ABSTRACT FROM AUTHOR]

We study the behavior of 3-D periodic composite media consisting of several types of split-ring resonators. By initially introducing the H-D periodic eigenmode finite element method (FEM) formulation, the dual counterpart of our formerly proposed E-B formulation, we are able to extract accurate dispersion diagrams and field distributions of electromagnetically complex structures and compare the returned characteristics of the supported modes. Using Babinet’s principle, we design the corresponding complementary resonators and evaluate their dual characteristics. Particular attention is given to the explanation of the behavior of these composite media under wave incidence perpendicular to the scatterers’ plane. Additionally, we perform a cross-check with excitation problem results, to interpret the response predicted by analytical models existing in literature and confirmed by the eigen-analysis of the structures. Useful conclusions are drawn concerning the potential utilization of the studied resonators in more complex structures in the field of microwave applications. [ABSTRACT FROM AUTHOR]

The article introduces a photonic crystal fiber (PCF)-based single polarizing filter for a dual-communication band with strongest filter intensity and broad-bandwidth of crosstalk (CT) more than 20 dB, working on the surface plasmon resonance (SPR) principle. The finite-element method (FEM) is used to investigate the filter characteristics of gold-coated PCF. The proposed PCF shows single-polarization filtering in two communication bands of 1.63 and $1.378~\mu \text{m}$. In phase-matching conditions, the core-guided propagation mode coupled with the surface plasmon polariton (SPP) mode results in the occurrence of SPR. The $y$ -polarized core mode is coupled with the $y$ -polarized SPP mode and therefore the light energy is transferred from the $y$ -polarized core mode to the $y$ -polarized SPP mode, hence the confinement loss of $y$ -polarized core mode is much higher than that of the $x$ -polarized core mode. Therefore, the single polarization filter can be retaining the core guided mode always in the $x$ -polarized direction for a wide-wavelength range. In the optimized PCF, the confinement loss of the core mode in the $y$ -polarized direction reaches an extremely higher value of 2953 dB/cm at 1.63 $\mu \text{m}$ and 450.8 dB/cm at 1.378 $\mu \text{m}$ , but in the $x$ -polarized direction loss is only 149.3 dB/cm at 1.63 $\mu \text{m}$ and 4.658 dB/cm at 1.378 $\mu \text{m}$. Besides, the CT reaches the maximum value of 2435 dB at $1.63~\mu \text{m}$ and 387.5 dB at $1.378~\mu \text{m}$ with the fiber length of 1 mm, and the corresponding bandwidth of CT above 20 dB is 591 nm. Moreover, it is easier to operate the SPR-PCF-based polarization filter devices. [ABSTRACT FROM AUTHOR]

A generalized formulation of earth-return impedance and admittance for overhead lines above a multi-layer earth is derived. An equivalent homogeneous earth method (EHEM) and a Method of Moments - Surface Admittance Operator (MoM-SO) method with modified earth-return Green function considering an N-layer earth are also proposed. The frequency responses of wave propagation characteristics are evaluated by the newly proposed formulas and compared to those found from existing formulas in software used for the simulation of electromagnetic transients. Transient simulations performed in an electromagnetic transient (EMT) type simulation tool are also presented. It is shown that the proposed generalized formulas, the EHEM and the modified MoM-SO method, are in agreement, validating and verifying the results found in this paper. [ABSTRACT FROM AUTHOR]

Wepropose a design for coupled-core multi-core fibers that allows to achieve extremely low levels of modal dispersion. These fibers, which we dub NEar-zero MOdal-dispersion (NEMO) fibers, have an even number of cores regularly distributed on a circle, and the optimal design parameters follow from a simple condition independent of the number of cores. The modal-dispersion reduction trades off some of the fiber mode-mixing effectiveness, yet without compromising its beneficial property of mitigating nonlinear signal distortions. The semi-analytical tool developed for this study allows to effectively characterize the effect of various types of perturbations to the ideal fiber structure. [ABSTRACT FROM AUTHOR]

In this work, we present a stochastic theoretical analysis of an electromagnetic wave propagating inside a planar slab waveguide filled with a cholesteric material. In this system, the propagation constant of the wave is assumed to be a randomly fluctuating parameter. By means of the van Kampen systematic expansion method, Maxwell’s electromagnetic equations with random coefficients, and appropriate boundary conditions, are obtained. Numerical examples of the effects of the randomness on the propagating constant, on the ratio between magnetic and electric modes, on the field profiles, and on the energy flow are given. The results show that the stochastic waveguide can support multiple Transverse Magnetic (TM) or Transverse Electric (TE) modes with the same cutoff frequency, and furthermore, they support a distribution of electric and magnetic fields with phase shift. Our results are consistent with those of an isotropic waveguide. [ABSTRACT FROM AUTHOR]