Commercial Electromagnetic Simulation Research Articles

Design of a Half-Mode Substrate-Integrated Waveguide (HMSIW) Multimode Resonator Bandpass Filter Using the Minkowski Fractal for C-Band Applications.

A substrate-integrated waveguide (SIW) bandpass filter (BPF) with extraordinary selectivity and an adequate upper stopband for C-band Satellite Communication (SATCOM) applications is proposed in this paper. The design comprises comb-shaped slots engraved on a half-mode SIW (HMSIW) that constitute a multimode resonator (MMR). Its performance is further ameliorated by applying the first and second iterations of the Minkowski fractal curve in the ground plane as a defected ground structure (DGS). The Minkowski fractal has advantages in terms of better bandwidth and miniaturization. The filter is first simulated using the commercial full-wave electromagnetic simulator HFSS v19 and then fabricated on a 0.062'' (1.6 mm) FR4 with dielectric constant εr = 4.4. The measured results are comparable with the simulated ones and demonstrate that the BPF has a resonant frequency (f0) of 4.75 GHz, a 3 dB bandwidth of 770 MHz (fractional bandwidth of 21.4%), an insertion loss of 1.05 dB, and an out-of-band rejection (in the stopband) of more than 28 dB up to 8 GHz, demonstrating a wide and deep stopband. Using the multimode resonator (MMR) technique, a wide bandwidth has been achieved, and by virtue of using half-mode SIW (HMSIW), the proposed BPF is compact in size. Also, the fractal DGS aids in better stopband performance.

Design of high performances electronically reconfigurable antenna arrays by means of parasitic structures and RF-MEMS switches

AbstractThis work explores the development of smart array antennas, able to electronically change their beam patterns through reconfigurable linear, planar, or conformal parasitic structures controlled by mean of a set of electronic switches namely the radio frequency micro-electromechanical switches (RF-MEMS). The motivation of this study is to extend and make competitive the use of reconfigurable antenna arrays in areas such as the Internet of Things (IoT) and wireless sensor networks. These hot research areas require a capillary distribution of sensors characterized by compact dimensions and limited cost. The radiating systems play a key role in such applications since the improvement of the radiating properties can dramatically reduce the power consumption of such sensors and extend their operative range. Standard smart antenna arrays such as phased, or fully adaptive arrays are extremely expensive, expensive and difficult to control. In this work, the use of smart reconfigurable antenna arrays that do not require expensive digital variable phase shifters and attenuators has been considered. The proposed antenna structures are based on reconfigurable parasitic structures, that thanks to suitable RF-MEMs switches are able to obtain a desired beam pattern, by steering the main beam in a given direction, removing eventually interfering signals and maximizing the signal-to-noise ratio SNR. The versatility, simplicity, and low cost of such antennas make them particularly suitable for the emergent wireless sensor networks and IoT applications. Theoretical background, design guidelines, and suggestions for their fabrication are detailed in this work. Some antenna models for different practical applications are designed, optimized, numerically assessed with commercial electromagnetic simulators, and commented to provide a valid alternative to researchers involved in antenna design for IoT applications.

Room temperature photon-magnon coupling in YIG- electric field coupled resonator system

This study presents a planar hybrid system consisting of an electric-field-coupled resonator (ELCR) and yttrium iron garnet (YIG) film, designed to investigate the interaction between photons and magnons at room temperature. This hybrid system has been designed and simulated using the commercial electromagnetic full-wave simulator CST Microwave Studio. The phenomenon of anti-crossing between the photon mode of the ELCR and the magnon modes of the YIG was observed by analyzing the |S21|-versus-frequency spectrum under varying strengths of bias magnetic fields. We present a comprehensive theoretical framework that explains the observed anti-crossing effect resulting from photon-magnon coupling (PMC) and provide estimations for the strength of PMC (Δ). Additionally, the interaction between photons and magnons was manipulated through two distinct methods: by adjusting the thickness (tYIG) of the YIG film and by positioning the YIG films along the microstripline. For the ELCR (for tYIG = 25 μm), Δ comes to 58 MHz, while changing tYIG from 2 μm to 50 μm, enabling more precise control of the Δ parameter across the span of 17 MHz to 84 MHz. Similarly, the YIG positioning at a different location along the microstripline allowed manipulation of Δ from 5 to 50 MHz. The resultant PMC can be significantly tuned by 400% to 900% in a planar-geometry ELCR-YIG hybrid system. This research offers avenues for developing innovative hybrid systems that afford greater control over the magnitude of PMC in a planar configuration, representing a promising direction for future advancements in hybrid magnonic systems.

Radiation Properties of Two Elements Microstrip Antenna Array at Microwave Frequencies

One of the key challenges in developing radio communication systems is the creation of tiny solid-state radiation sources, particularly in the microwave and millimeter range.An antenna serves as the efficient interface between electronic circuits and the external environment, making it a crucial element in the growing trend of using high frequencies in contemporary wireless communications.The card actively contributed to the development of several subsystems for an active monolithic Phased Array Antenna, which utilizes solutions in space technology and antenna technologies operating at frequencies of around 30 GHz and 28 GHz, such as Local Multipoint Distribution (LMDS). This document primarily focuses on the study method and the two components of active patch arrays. The radiation models were computed utilizing the cavity plate model, the Simple Green model, and the rigorous commercial Electromagnetic Simulator. The active rectangular patches with the Gann diode were reconfigured and assembled into arrays in the E-plane and H-plane. The calculated and measured findings for both active arrays have proved the potential for beam scanning. All three models have accurately projected radiation levels across a wide range of steering controls. To ensure stable operation, a thin dielectric layer was positioned in front of the H plane of the array. The impact of the dielectric layer on the even and odd modes of the array has been demonstrated.

ÇİFT-BANT İRİS POLARİZÖR TASARIM VE OPTİMİZASYONU

The structure that transforms a linear polarized signal into right-hand or left-hand circularly polarized signals is called a polarizer. In this study, a dual-band waveguide polarizer used in satellite communications is presented. The waveguide polarizer is designed using iris structures on a square waveguide. The purpose of the polarizer is to transmit the ±45° tilted linearly polarized signal at its input to the output as a right-hand or left-hand circularly polarized wave, and vice versa. At the input of the polarizer, a transition is designed between the WR42 waveguide and the square waveguide. At the output stage, a transition from square waveguide to circular waveguide is designed. In this paper, the design steps of both the polarizer and the transition sections, the optimization parameters, and simulation results are presented in full detail. The simulations are performed with a commercial electromagnetic simulation software, CST Studio Suite. The design operates within the Ka-band, specifically at 17.2 – 21.2 GHz and 27.5 – 31 GHz frequency bands. The insertion loss of the iris polarizer is 23 dB, and the phase difference is less than 15° around 90° for both bands.

An efficient and low-profile metasurface-based polarization converter with linear and circular polarization efficiencies for X- and Ku-Band applications

In this study, a metasurface-based linear and circular polarization converter operating on the reflection mode is proposed for X- and Ku-band microwave applications. The proposed converter offers an optimum performance with a polarization conversion ratio (PCR) and polarization matching ratio (PMR) greater than 93 in the bandwidth for a linearly polarized in the y-direction and right-handed circular polarized (RHCP) incident waves. Besides, the design performs over 80 PCR performance up to under oblique incidence. Moreover, the proposed converter is capable of left-handed circular polarization conversion between 7.42 and 7.68 GHz for a y-polarized incident wave. The design offers a relative bandwidth (RBW) of 71.36. The converter design is constructed with metal termination, an easily accessible FR-4 substrate and a simple design metasurface. Surface currents of the polarization converter at resonance frequencies of 8.77, 12.88 and were examined to understand its working mechanism. In addition, when the proposed design is rearranged with the appropriate geometry, the monostatic RCS reduction value in the 8.0–17.7 range is observed to be higher than 10 dB. CST program (a commercial 3D electromagnetic simulator) was used in simulations. The simulated device was fabricated with a traditional board fabrication technique. Simulation results were verified with free space measurements calibrated by the thru-reflect-line calibration procedure. The performance and efficiency of the proposed polarization converter were compared with other converters in the literature.

Spectral-Domain Method of Moments for the Modal Analysis of Line Waveguides

A rigorous full-wave modal analysis based on the method of moments in the spectral domain is presented for line waveguides constituted by two-part impedance planes with arbitrary anisotropic surface impedances. An integral equation is formulated by introducing an auxiliary current sheet on one of the two half planes and extending the impedance boundary condition of the complementary half plane to hold on the entire plane. The equation is then discretized with the method of moments in the spectral domain, by employing exponentially weighted Laguerre polynomials as entire-domain basis functions and performing a Galerkin testing. Numerical results for both <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">bound</i> and <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">leaky</i> line waves are presented and validated against independent results, obtained for isotropic surface impedances with the analytical Sommerfeld–Maliuzhinets method and for the general anisotropic case with a commercial electromagnetic simulator. The proposed approach is computationally efficient, can accommodate the presence of spatial dispersion, and offers physical insight into the modal propagation regimes.

Millimetre-wave and sub-THz maritime radar scene simulation

Situational awareness for small maritime craft is of vital importance for improved marine safety of both the craft and other water users, as well as being paramount for path planning and obstacle avoidance in the development of small autonomous vessels. As part of a wider experimental and theoretical research program, here we investigate the potential for use of commercial electromagnetic simulation software, to simulate multi-modal radar responses and high-resolution imagery of maritime scenes at mm-wave and sub-THz frequencies, incorporating a developed physical sea surface model. The ultimate goal is to use simulation in the development of radar anomaly detection algorithms and for situations where experimental measurements are logistically challenging. We also outline the procedure for experimentally verifying the simulated data using a wave tank as a controlled repeatable measurement environment.

Geodesic Half-Maxwell Fish-Eye-Lens Antenna

We propose and implement a geodesic half-Maxwell fish-eye (MFE)-lens antenna. The lens was optimized using an in-house physical optics (PO) code adapted for generalized geodesic lenses. The final antenna design was validated with commercial electromagnetic simulation software. The antenna combines a modulated geodesic half-MFE lens and a transition to a linear flare, which is needed to preserve the linear polarization in the aperture. The antenna prototype, designed to operate in the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{K}_{\mathrm {a}}$ </tex-math></inline-formula> -band, was manufactured with computer numerical control (CNC) milling and measured in an anechoic chamber. The design provides continuous beam scanning because of a mechanically actuated feed. Promising beam scanning properties are demonstrated in an angular range of ±45° with a scan loss below 3 dB, as well as good frequency stability from 26 to 32 GHz. Since the antenna is fully metallic, its radiation efficiency is high (approximately 90%).

An S-band cryogenic phased array feed for radio astronomy

Abstract We describe the design and ground testing of a prototype S-band cryogenic phased array feed. The feed uses 6-mm thick solid aluminium Vivaldi antennas, which were designed using a commercial electromagnetic simulation software. The antennas are designed for easy removal and 40 of them have been integrated into an array. The return loss, inter-element coupling, and beam patterns have been tested at room temperature and found to agree with simulations. For cryogenic testing the array has been combined with an existing analogue receiver chain and integrated into an cryostat. When tested at 30 K in aperture array mode the system was found to possess a minimum receiver temperature of 12 K. Increasing the number of elements and combining the array with a beam former would make it a suitable phased array feed for radio-astronomy applications.

Design of a Compact Dual-Frequency Microstrip Antenna using DGS Structure for Millimeter-Wave Applications

In this paper, a Millimeter-wave (MMW) antenna has been proposed for a current and future wireless application. The proposed model has two resonances at 30.5 GHz and 52.4 GHz. The proposed model has been designed and optimized using a commercial electromagnetic simulator (CST-Studio) and focused on attaining a return loss rate that is lower than -10 dB. The proposed MMW models are built on a small thick Rogers Substrate (RT-5880) with h = 0.508 mm for the thickness, relative permittivity of εr = 2.2, and tanδ = 0.0009 for the loss tangent, while the substrate has a width w_s equal to 6 mm and a length l_s equal to 6 mm. The design process of the model came at three steps, the first step after mathematical calculations has an output of model which has feeding port of 50 ohm with a feedline base length l_b of 0.5 mm and a feedline length l_f of 3 mm, the second step was by using the tapering techniques for enhancing matched impedance after initial calculations to have a length of tapering l_t equal to 1.8 mm, then finally extracting four corner slots to the patch for creating the final proposed model. The previous design process is to assure reliability, mobility, and high efficiency for the proposed antenna. The advantages of this model are the small size, low profile, low fabrication cost, and straightforward design structure. The proposed design can be employed for a variety of Millimeter-wave applications like wireless personal area network (WPAN) and 5G application in some countries like Colombia and Mexico. The proposed model has a moderate gain of 3 dBi to 7 dBi at resonance frequencies of 30.5 GHz and 52.4 GHz, which is one of the unique characteristics of the proposed antenna. The impedance bandwidth is between 28.7 Ghz and 32.6 GHz, which is equal 3.9 GHz, and 49.7 GHz to 56.2 GHz, which is equal to 6.5 GHz respectively for the proposed model, and satisfying efficiency of about 75% and 87% as calculated by CST -Studio, and a VSWR is equal to 1, All of these positive results are more than enough to satisfy the needs of millimeter-wave wireless applications.

Performance Study of Broadband and a Dual-Band Antenna- Array of Telecommunication Systems

The antenna is a Modified Broadband Butterfly Antenna (MBBA). The technical parameters of such systems are heavily influenced by the qualities of the antenna feed devices. The aperture theory of antennas uses the representation of the radiation field of the antenna as a superposition of the fields of elementary sources, characterized by their type and amplitude-phase spatial distribution. The radiation field of an antenna of finite dimensions is a superposition of inhomogeneous spherical waves emitted by the antenna elements. This paper is primarily the study process, Radiation models were calculated using the model of the cavity plates, Simple Green model, and the strict commercial Electromagnetic Simulator. The modified active rectangular patches with the Gann diode were combined into arrays of E and H plane. Calculated and measured results for these two active arrays the beam scanning, the possibilities have been demonstrated for both arrays. The results of an electrodynamics numerical simulation were obtained. Broadband and multiband radio systems have already found widespread practical applications by utilizing basic antenna parameters and characteristics.

Risk Analysis of HPEM Threats for Linear RF Channel with Pyramid Horn Antenna Based on System-Level SPICE Modeling

High power electromagnetics (HPEMs) pose a potential threatening risk to the wireless communication system, especially according to the main coupling path of the RF front-end channel. SPICE modeling of the responses coupled on the RF channel is crucial for the EM risk assessment, which helps us learn more about how the pulse conducts on the RF channel. A simplified linear RF channel with pyramid horn antenna is taken as an example by the selection of the key electronic modules of the actual wireless system. This paper proposes a system-level SPICE circuit model for the simplified RF channel according to the hybrid methods of the antenna electromagnetic simulation and SPICE modeling of the RF circuit. The equivalent circuits of the horn antenna illuminated by HPEMs are established with the Vector Fitting method based on Thevenin and Norton theorems. The short current response as the excitation files for the SPICE models are obtained by the commercial electromagnetic simulation of the horn antenna illuminated by Multiple HPEM environments. Equivalent circuits of a micro-strip bandpass filter are also derived with π type circuit structure based on the measured admittance data. Then we analyze the HPEM risk faced by the RF channel by considering multiple HPEM environments. The norm theory is utilized to analyze the waveform characteristics from electric fields of HPEMs to the responses of the RF channel. The ratios of the responses versus electric field for each norm are computed and the EM risk degree is ranked based on those results. The results demonstrate that high power microwave is the highest threatening risk for the linear RF channel compared to the other two HPEMs such as ultra-wide band, high altitude electromagnetic pulse. Finally, the flowchart of EM risk assessment is presented based on a previous analysis, which will benefit the EMC design in engineering.

Experimental characterisation and prediction of shielding effectiveness for multilayer carbon fibre reinforced composite materials with varying configurations

This paper reports the outcomes of an experimental investigation of the shielding effectiveness (SE) for carbon fibre reinforced polymer (CFRP) composites with varying configurations. It focuses on (1) important parameters affecting the SE of CFRP laminates and (2) applicability of the transmission line (TL) theory to predict their shielding properties. Comparison of the SE profiles showed that quasi-isotropic and cross-ply configurations perform equally well in attenuating the unpolarised radiation and only a modest increase of 10 dB is achieved by doubling the number of plies due to increased absorption. The applicability of the TL model for CFRP composites was found to be limited to thin laminates with quasi-isotropic lay-up, for which the accuracy prediction was within 5 dB in the 150 MHz-1 GHz frequency range. The experimental SE values were also compared to the full wave simulation in a commercial electromagnetic simulation software, demonstrating more accurate predictions than any analytical model.

Evaluation of Radiation Performances of Various Aperture and Horn Antennas over Sea Surface

Directional Currents Method (DCM) is applied to various aperture and horn antennas including rectangular aperture antenna, circular aperture antenna, dielectric loaded rectangular aperture antenna and E- and H-plane sectoral horn antennas to investigate their radiation performances analytically over sea surface in microwave bands. First, the expressions of the hypothetical directional currents of these antennas are derived in free space and the total radiation patterns are generated by MATLABTM. Then, the same antennas are simulated by the commercial electromagnetic simulation software CSTTM and compared to check the parametric accuracy of DCM numerically. In the second step, these directional currents are employed in deriving the analytical radiation fields of the antennas under investigation over sea surface by incorporating Green’s functions based on Norton’s formulation. This is followed by CSTTM simulations to observe the parametric accuracy of DCM expressions for microwave radiation over sea surface.

Radar Cross Section Prediction Using Iterative Physical Optics With Physical Theory of Diffraction

A new approach is presented to predict radar cross section (RCS) of electrically large conducting geometries using iterative physical optics (IPO) in conjunction with physical theory of diffraction (PTD). IPO is based on iterative refinement of physical optics (PO) currents to include multiple reflections. However, IPO does not yield sufficient accuracy in diffraction dominant regions since it does not properly include effects of edge diffractions. Hence, the proposed approach includes diffraction effects using PTD, which introduces edge currents. Diffracted fields due to these edge currents are radiated on triangular facets to modify the PO currents before IPO iterations. Scattered fields are computed from converged IPO surface currents and PTD edge currents. A new set of PTD edge currents excited by the fields due to the IPO currents are also found and the fields radiated by these PTD edge currents are added to the scattered fields. Therefore, interactions between the surface and edge currents are included. Computations are accelerated by parallel processing using message passing interface (MPI). Monostatic and bistatic RCS are predicted using the proposed approach for tail-wing and trihedral corner reflector geometries. The IPO-PTD results are compared with method of moments (MoM) and multilevel fast multipole method results obtained using field calculations involving bodies of arbitrary shape (FEKO) commercial electromagnetic simulation software for validation.

An Efficient Computational Technique for the Electromagnetic Scattering by Prolate Spheroids

In this paper we present an efficient Matlab computation of a 3-D electromagnetic scattering problem, in which a plane wave impinges with a generic inclination onto a conducting ellipsoid of revolution. This solid is obtained by the rotation of an ellipse around one of its axes, which is also known as a spheroid. We have developed a fast and ad hoc code to solve the electromagnetic scattering problem, using spheroidal vector wave functions, which are special functions used to describe physical problems in which a prolate or oblate spheroidal reference system is considered. Numerical results are presented, both for TE and TM polarization of the incident wave, and are validated by a comparison with results obtained by a commercial electromagnetic simulator.

An effective metasurface-based linear and circular polarization converter for C- and X-band applications

In this study, a reflection-mode metasurface-based linear and circular polarization converter is designed for common microwave frequencies (C-band (5.85–8.20 GHz) and X-band (8.20–12.40 GHz)). The proposed polarization converter possesses a right-handed circular polarization (RHCP) capability in the 5.35–5.94 GHz frequency range and a left-handed circular polarization conversion (LHCP) capability in the 8.88–12.03 GHz frequency range. Besides its circular polarization converter capability, it demonstrates linear polarization transformation in the 4.61–4.85 GHz and 6.86–7.78 GHz frequency ranges with a polarization converter rate (PCR) greater than 90%. The design provides an oblique incidence performance up to 45° with 80% PCR value in linear polarization. The CST Microwave Studio (a commercial 3D electromagnetic simulator) was used to obtain simulation results of the design. For validation, the designed converter was first fabricated using the conventional circuit-board method, and then its reflection coefficient was measured by a microwave measurement setup calibrated by the thru-reflect-line method. A good agreement was observed between simulated and experimental results. Finally, the proposed converter design was compared with other converter designs in the literature to examine its effectiveness.

Analytical Estimation of the Efficiency of Surface-Wave-Excited Plasma Monopole Antennas

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.

Integral Equation Formulation for Planar Plasmonic Structures With Finite Thickness in Layered Media

A detailed Volume Integral Equation (VIE) formulation for planar plasmonic nano structures with finite thickness in flat multi-layers medium is presented. The boundary condition along the localized metallic objects is expressed in terms of the unknown polarization current flowing through these objects in the form of an integral equation, which is solved using the Method of Moments (MoM). The Green's functions associated with a layered medium of practical importance are expressed in the spectral domain. The corresponding spatial domain Green's functions are obtained using the Discrete Complex Images Method (DCIM). Special treatment for the spectral function's asymptote at high spectral values is performed. The presented formulation is applied on different plasmonic structures immersed inside layered media. The structures include nano-rod and nano-patch excited by an incident plane wave. In addition, a simple band-stop filter based on quarter-wavelength stubs is considered. This filter is fed with a couple of plasmonic transmission lines. The obtained current distributions and <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">S</i> -parameters are compared with those obtained using a commercial full-wave electromagnetic simulator, namely CST Microwave Studio. A very good agreement is observed. The proposed integral equation formulation enjoys high degree of stability, numerical efficiency, and accuracy.