Electromagnetic Simulation Model Research Articles

Analysis of Influence of Grid-Following and Grid-Forming Static Var Generators on High-Frequency Resonance in Doubly Fed Induction Generator-Based Wind Farms

In Doubly Fed Induction Generator (DFIG)-based wind farms with Static Var Generators (SVGs), high-frequency resonance will be more like to occur when an unloaded cable is put into operation, which will threaten the stable operation of the wind farm. To address this issue, the influence of power outer loops on the impedance of grid-connected inverters is considered. Based on harmonic linearization, theoretical models for the sequence impedances of DFIGs, Grid-following (GFL) SVGs, and Grid-forming (GFM) SVGs are established. The correctness of the three models is verified by impedance scanning using the frequency sweep method. Through a comparative analysis of these sequence impedances, it is found that unlike the GFM SVG (which exhibits inductive impedance), the GFL SVG exhibits capacitive impedance in the high-frequency band, which leads to negative damping characteristics in the high-frequency band for the wind farm system with the grid-following SVG; thereby, the risk of high-frequency resonance also increases accordingly. On the contrary, GFM control adopted by SVGs can effectively eliminate the negative damping region in the high-frequency band for wind farms to suppress high-frequency resonance. Meanwhile, for grid-forming SVGs, the parameter variations in power synchronous loops have no significant impact on the suppressing effect of high-frequency resonance for wind farms. Finally, an electromagnetic simulation model for a DFIG-based wind farm system with an SVG is established using the StarSim-HIL (hardware-in-the-loop) experiment platform, and the simulation results validate the correctness of the theoretical analysis.

Antenna optimization using machine learning with reduced-dimensionality surrogates

In modern times, antenna design has become more demanding than ever. The escalating requirements for performance and functionality drive the development of intricately structured antennas, where parameters must be meticulously adjusted to achieve peak performance. Often, global adjustments to geometry are necessary for optimal results. However, direct manipulation of antenna responses evaluated with full-wave electromagnetic (EM) simulation models using conventional nature-inspired methods entails significant computational costs. Alternatively, surrogate-based techniques show promise but are impeded by dimensionality-related challenges and nonlinearity of antenna outputs. This study introduces an innovative technique for swiftly optimizing antennas. It leverages a machine learning framework with an infill criterion employing predicted enhancement of the merit function, utilizing a particle swarm optimizer as the primary search engine, and employs kriging for constructing the underlying surrogate model. The surrogate model operates within a reduced-dimensionality domain, guided by directions corresponding to maximum antenna response variability identified through fast global sensitivity analysis, tailored explicitly for domain determination. Operating within this reduced domain enables building dependable metamodels at a significantly lower computational cost. To address accuracy loss resulting from dimensionality reduction, the global optimization phase is supplemented by local sensitivity-based parameter adjustment. Extensive comparative experiments involving various planar antennas demonstrate the competitive operation of the presented technique over machine learning algorithms operating in full-dimensionality space and direct EM-driven bio-inspired optimization techniques.

Safety Assessment of Gender-specific Human Electromagnetic Exposure with Aortic Valve Stents for EV-WPT

Electric vehicle wireless power transfer brings additional electromagnetic exposure (EME) risks to the human body, especially those with metal implants. This paper focuses on the safety assessment of human EME with aortic valve stents (AVS), and establishes electromagnetic simulation models for different genders of humans, AVS, and electric vehicle-wireless power transfer (EV-WPT) systems. The transmission power of the EV-WPT system is 11 kW. Considering the uncertainty of the EV-WPT system and AVS in practical use, an efficient deep neural network method is proposed to evaluate the EME safety to different genders of humans. Using the standard limits of the International Committee on Non-Ionizing Radiation Protection (ICNIRP) as the judgment standard, comparing human EME under static conditions, it is demonstrated that AVS can change the distribution of induced electric fields in the human body and increase the risk of human EME. Moreover, the probability of male human EME exceeding the standard limits is 22.78% higher than that of female human.

Design and analysis of high power density permanent magnet-assisted synchronous reluctance motor

Permanent magnet-assisted synchronous reluctance motor (PMSRM) has been widely used in many fields due to their advantages of less permanent magnets and low cost. However, the permanent magnet torque and reluctance torque of the traditional PMSRM reach their maximum values at different current angles. Therefore, the utilization ratio of the total torque to each torque component is low, which leads to the low power density of the PMSRM. To solve this problem, a new rotor structure suitable for PMSRM is proposed in this paper. The rotor can improve the total torque by increasing the maximum value of permanent magnet torque and the utilization rate of total torque to each torque component. Thus, the power density of the motor is effectively improved. In order to realize the matching design of each parameter in the proposed rotor structure, the Taguchi method is used to optimize the design, and the influence of each optimization variable on torque and torque ripple is analyzed. The finite element simulation analysis method is used to establish the electromagnetic simulation model of the traditional structure, the new structure proposed and the optimized structure of the new structure by Maxwell simulation software. The simulation results show that the proposed new rotor structure not only effectively improves the torque density, but also effectively reduces the torque ripple.

Analysis of Parameter Sensitivity to Overvoltage under DC Commutation Failure

Abstract In recent years, the growing integration of renewable energy sources into power systems has highlighted the significance of enhancing the grid’s capacity to accommodate these resources efficiently. Direct Current (DC) transmission stands out as a pivotal solution to bolster the integration of renewable energy. This study delves into the critical issue of overvoltage occurrences at the sending end, particularly triggered by failures in DC commutation. Through the development of a comprehensive PSCAD electromagnetic simulation model encompassing synchronous machines, centralized renewable energy sources, along with DC components, the research rigorously investigates the intricacies of DC commutation failures. Specifically, it explores their underlying mechanisms responsible for inducing overvoltage at the sending end. Furthermore, the paper undertakes an extensive analysis of the voltage dynamic processes and their associated sensitivity factors, shedding light on crucial aspects of grid stability and resilience in the face of evolving energy landscapes.

A novel method for calculating broadband electrical performance of high-speed aircraft radome under thermo-mechanical-electrical coupling

The electrical performance of radomes on high-speed aircraft can be influenced by the thermal and mechanical loads produced during high-speed flight, which can affect the detection distance and accuracy of the guidance system. This paper presents a new method that uses the Finite Difference Time Domain (FDTD) method to calculate the electrical performance of radomes under Thermo-Mechanical-Electrical (TME) coupling. This method can accurately characterize the effects of material dielectric temperature drift and structural deformation on the electrical performance of the radome under flight conditions, enabling high-precision full-wave calculations of the broadband electrical performance of the radome. The method initiates by utilizing a Finite Element Grid Model (FE-GM) of the radome to sequentially acquire the radome’s response temperature field and structural deformation field through thermal and mechanical simulations. Subsequently, spatial mapping techniques are developed to accurately incorporate the dielectric temperature drift and structural deformation of the radome into its Yee grid Electromagnetic (EM) simulation model. A verification case was designed to test the proposed method, and the results confirmed its high computational accuracy. Additionally, the effectiveness and necessity of the method were further demonstrated by analyzing the electrical performance of a fused silica ceramic radome used on a high-speed aircraft.

Research on Vibration Characteristic Analysis and Fault Diagnosis Method of Oil‐Immersed Transformer Based on Multi‐Physics Coupling

The oil‐immersed transformer is a crucial power equipment in power system, which is prone to abnormality or failure under long running. In order to improve the level of operation and maintenance and ensure the safe and reliable operation of the power grid, it is necessary to diagnose the fault of the oil‐immersed transformer in time. Most of the traditional fault vibration methods are off‐line detection, and are easily disturbed by mechanical deterioration. In order to solve the above problems, this paper established a 3D electromagnetic and stress coupling simulation model of oil‐immersed transformer by finite element simulation software. The vibration characteristics of oil‐immersed transformer core winding are obtained, and at the same time, this paper obtained the vibration signals at different positions on transformer core winding and oil tank. According to the vibration signal of the transformer, the best measuring point position of the tank wall is proposed to accurately reflect the vibration characteristics of the transformer. The signal data is preprocessed by CEEMDAN decomposition method, and the signal data is classified by GWO‐BP composite classification algorithm. This paper proposed an online transformer fault diagnosis method based on vibration signal, which achieves the purpose of accurately diagnosing oil‐immersed transformer faults. The test results show that in the case of oil‐immersed transformers the accuracy of the proposed transformer fault diagnosis method is more than 93%, which provides important guiding significance for the safe and stable operation of the transformer. © 2024 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC.

Electromagnetic field simulation modeling method and distribution characteristics of electric vehicle wireless charging system

In recent years, wireless charging technology for electric vehicles has gained significant attention. To accurately analyze the distribution characteristics of the electromagnetic field during the wireless charging process of electric vehicles, a finite element-based electromagnetic analysis method was employed. Applied in the commercial simulation software, the electromagnetic environment of the resonant coil and electric vehicle model was simulated under high-power charging conditions, resulting in an overall electromagnetic field distribution for the electric vehicle. The results indicated that within the coil region, the magnetic induction intensity in the central area of the coil was zero, and it increased as the distance from the center of the coil grew. Outside the coil region, the magnetic induction intensity gradually decreased. The electric field intensity of the resonant coil was maximum in the central area of the coil, and it weakened as the distance from the center of the coil increased. When a magnetic shielding resonant coil was used, the electromagnetic field was confined between the shielding materials, and the magnetic field rapidly attenuated on both sides of the magnetic shield. The electromagnetic field energy of the electric vehicle body was mainly concentrated at the bottom of the vehicle near the coil. When the coil was located in the front of the car body, the maximum electric field intensity distribution in the car body was 8.50 V/m, and the maximum magnetic induction intensity was 0.024 μT. When the coil was located in the middle of the car body, the maximum electric field intensity was 2.31 V/m, the maximum magnetic induction intensity was 0.019 μT. As the distance from the coil position increased, the energy weakened.

An EIRP Measurement Method of High-Power Microwave Systems Based on Near-Field Testing

The equivalent isotropic radiated power (EIRP) of high-power microwave (HPM) systems is a core-evaluating indicator. In practical testing, locating a suitable test site for the far-field method becomes challenging due to the requisite antenna separation. The conventional near-field method necessitates the extraction of the antenna’s near-field distribution, resulting in a testing system of intricate complexity and diminished efficiency. Therefore, the traditional near-field method cannot be directly applied in HPM systems. In the present study, a new EIRP measurement method for HPM systems based on near-field testing was proposed. First, a monitoring antenna of a considerable scale is positioned within the near-field vicinity of the HPM antenna to capture radiation power, thereby deriving its equivalent input power. Subsequently, according to the EIRP definition and the measured gain of the HPM antenna, the EIRP of the HPM system can be acquired. Theoretical research on this measurement method was conducted, the electromagnetic simulation model was constructed, and a comprehensive analysis through simulation was undertaken. A measurement system was developed and verified experimentally. The results demonstrate the precision of this approach in determining the EIRP of the HPM system, thereby serving as a valuable tool for assessing the power-handling capability of the HPM antenna. The test error is ±0.5 dB.

On Accelerated Metaheuristic-Based Electromagnetic-Driven Design Optimization of Antenna Structures Using Response Features

Development of present-day antenna systems is an intricate and multi-step process requiring, among others, meticulous tuning of designable (mainly geometry) parameters. Concerning the latter, the most reliable approach is rigorous numerical optimization, which tends to be resource-intensive in terms of computing due to involving full-wave electromagnetic (EM) simulations. The cost-related issues are particularly pronounced whenever global optimization is necessary, typically carried out using nature-inspired algorithms. Although capable of escaping from local optima, population-based algorithms exhibit poor computational efficiency, to the extent of being hardly feasible when directly handling EM simulation models. A popular mitigation approach involves surrogate modeling techniques, facilitating the search process by replacing costly EM analyses with a fast metamodel. Yet, surrogate-assisted procedures feature complex implementations, and their range of applicability is limited in terms of design space dimensionality that can be efficiently handled. Rendering reliable surrogates is additionally encumbered by highly nonlinear antenna characteristics. This paper investigates potential benefits of employing problem-relevant knowledge in the form of response features into nature-inspired antenna optimization. As demonstrated in the recent literature, re-formulating the design task with the use of appropriately selected characteristic locations of the antenna responses permits flattening the functional landscape of the objective function, leading to faster convergence of optimization procedures. Here, we apply this concept to nature-inspired global optimization of multi-band antenna structures, and demonstrate its relevance, both in terms of accelerating the search process but also improving its reliability. The advantages of feature-based nature-inspired optimization are corroborated through comprehensive (based on three antenna structures) comparisons with a population-based search involving conventional (e.g., minimax) design problem formulation.

3‐D woven rectangular hollow structure conformal bearing microstrip antenna with different heights: Design, preparation, performance, and simulation

AbstractTraditional microstrip antennas have problems with heavy weight and poor gain. In order to reduce the weight of the antenna itself and improve its gain, the preforms of the 3‐D woven rectangular hollow structure conformal bearing microstrip antenna (3DWRHS‐CB‐MA)with different heights were woven from ultra‐high molecular weight polyethylene (UHMWPE) filament yarns and copper wires on a common loom through reasonable design. The preform was used as the reinforcement and epoxy resin was used as the matrix, four different heights (2, 4, 6, and 8 mm) of 3DWRHS‐CB‐MA were prepared by vacuum‐assisted resin transfer molding (VARTM) process. Finally, the electromagnetic performance was analyzed by high‐frequency structure simulator (HFSS) and experimental testing. The results showed that the frequency deviation of the 2 mm height microstrip antenna was minimal; while the 4 mm height microstrip antenna had better gain efficiency and directional diagram compared to others. The 4 mm height microstrip antenna has good radiation performance with a weight of only 35 g which shows that 3DWRHS‐CB‐MA are potential candidates for future intelligent textile materials and wireless communication fields.Highlights Weaving with UHMWPE filament yarns and copper wires on common looms. The preform was used as the reinforcement, and epoxy resin was used as the matrix. Simulation of electromagnetic characteristics of antennas using HFSS software. Proving the effectiveness of the electromagnetic simulation model. Revealing the electromagnetic radiation mechanisms.

Numerical and Experimental Investigation of Time-Domain-Reflectometry-Based Sensors for Foreign Object Detection in Wireless Power Transfer Systems

Foreign object detection (FOD) is considered a key method for detecting objects in the air gap of a wireless charging system that could pose a risk due to strong inductive heating. This paper describes a novel method for the detection of metallic objects utilizing the principle of electric time domain reflectometry. Through an analytical, numerical and experimental investigation, two key parameters for the design of transmission lines are identified and investigated with respect to the specific constraints of inductive power transfer. For this purpose, a transient electromagnetic simulation model is established to obtain and compare the sensor impedance and reflection coefficients with experimental data. The measurement setup is based on parametrically designed sensors in laboratory scale, using an EUR 2 coin as an exemplary test object. Consequently, the proposed simulation model has been successfully validated in this study, providing a comprehensive quantitative and qualitative analysis of the major transmission line design parameters for such applications.

High-efficacy global optimization of antenna structures by means of simplex-based predictors

Design of modern antenna systems has become highly dependent on computational tools, especially full-wave electromagnetic (EM) simulation models. EM analysis is capable of yielding accurate representation of antenna characteristics at the expense of considerable evaluation time. Consequently, execution of simulation-driven design procedures (optimization, statistical analysis, multi-criterial design) is severely hindered by the accumulated cost of multiple antenna evaluations. This problem is especially pronounced in the case of global search, frequently performed using nature-inspired algorithms, known for poor computational efficiency. At the same time, global optimization is often required, either due to multimodality of the design task or the lack of sufficiently good starting point. A workaround is to combine metaheuristics with surrogate modeling methods, yet a construction of reliable metamodels over broad ranges of antenna parameters is challenging. This work introduces a novel procedure for global optimization of antenna structures. Our methodology involves a simplex-based automated search performed at the level of approximated operating and performance figures of the structure at hand. The presented approach capitalizes on weakly-nonlinear dependence between the operating figures and antenna geometry parameters, as well as computationally cheap design updates, only requiring a single EM analysis per iteration. Formal convergence of the algorithm is guaranteed by implementing the automated decision-making procedure for reducing the simplex size upon detecting the lack of objective function improvement. The global optimization stage is succeeded by gradient-based parameter refinement. The proposed procedure has been validated using four microstrip antenna structures. Multiple independent runs and statistical analysis of the results have been carried out in order to corroborate global search capability. Satisfactory outcome obtained for all instances, and low average computational cost of only 120 EM antenna simulations, demonstrate superior efficacy of our algorithm, also in comparison with both local optimizers and nature-inspired procedures.

Levitation Force Compensation Study for HTS Maglev System Based on the Input of Electromagnetic Force

The advantages of levitation and guidance integration make the high-temperature superconducting (HTS) maglev system have great potential in the field of high-speed transportation. However, due to the influence of some factors such as the Dewar (a low temperature thermostat for superconductors) vacuum increases and magnetic field irregularity, the levitation force will decline and working height will drop. To solve the problems, this paper proposes a compensation method based on electromagnetic auxiliary device. Firstly, the thought and purpose of this method are explained in detail. Secondly, the effectiveness of levitation force compensation is verified by experiment. Then, electromagnetic simulation model is established and its correctness is verified by comparing simulation results and experimental data. Finally, dynamic simulation is conducted based on the verified model to study the vibration characteristics of Dewar system. The results show that the auxiliary device can compensate the levitation force and suppress vibration well. Meanwhile, comparing with the field cooling height (FCH) at 20 mm and 30 mm, the compensation effect of former is better than latter, but the overall maximum levitation force of latter is higher than former. This research provides an economical and effective way to achieve the levitation force compensation of HTS maglev system. Furthermore, the electromagnetic auxiliary device is an active energy input port, providing the possibility for the active control of HTS system. It is expected to provide reference for future practice in relevant application fields.

Analysis of Electromagnetic Interference for Anti-Medal UHF RFID Temperature Tag in High Power Electronic Equipment

Being inches from the rapid development of new energy technology, the capacity of high-power power electronic equipment is increasing rapidly, and the requirements for its safe and reliable operation are also rising. As a result, the demand for online temperature monitoring of such equipment is becoming increasingly urgent. RFID temperature measurement technology can be used for real-time monitoring of the temperature of powered operation equipment. However, the operation of high-power electronic equipment generates strong electromagnetic interference, which can seriously affect the normal operation of RFID temperature measurement systems. For applications involving the internal temperature measurement of high-power power electronic equipment, this paper employs an RFID anti-metal temperature tag antenna with a short-circuit cutoff structure. This structure was tested in an excitation switchgear cabinet. During the low-power operation of the cabinet, the temperature tag functioned normally. By combining an RFID antenna model with an electromagnetic interference simulation model of the main circuit of the excitation switchgear cabinet, this paper establishes an electromagnetic interference simulation model for an RFID temperature tag. It analyzes how the tag’s antenna performance parameters change when subjected to interference. Through simulation, the failure mechanism of the RFID temperature tag during the high-power operation of the excitation switchgear cabinet is clarified. The analysis found that there are both conductive electromagnetic interference and radiated electromagnetic interference in the excitation switchgear cabinet, with the conductive electromagnetic interference having a more significant effect. Conductive electromagnetic interference can seriously impact the performance of RFID temperature tags in the excitation switchgear cabinet, significantly degrading their performance. In contrast, the effect of radiated electromagnetic interference on the tags is relatively small. Therefore, this paper employs anti-metal RFID temperature tags and simulates and analyzes their electromagnetic interference characteristics.

Electromagnetic disturbance characteristic of typical high voltage switchgear interruption process in offshore wind farm based on integrated conduction model

AbstractIn an offshore wind farm, a high‐voltage switchgear interruption in an offshore substation creates a high‐frequency, high‐amplitude overvoltage that can cause severe electromagnetic interference problems in the intelligent electronic device. To address this issue, mathematical models, vector fitting and finite element method were used to build an integrated electromagnetic disturbance conduction model, whose accuracy was verified by large current interruption tests. Through the simulation of a typical offshore wind farm's single‐phase grounding fault interruption process, the electromagnetic disturbance characteristics and the impact of the ground position are obtained. The results show that during the fault interruption process of phase B grounded, the dominant frequency of disturbance voltage can reach 4.34 MHz, and the amplitude can reach 1.12 kV. The ground grid has a large impact on the interference voltage, which can reach a maximum value of 2.28 kV under specific conditions. The disturbance voltage in the fault process mainly comes through the current transformer, while during the interruption process, it mainly comes through the ground grid. The authors provide a method to establish the integrated electromagnetic disturbance simulation model, which can improve the accuracy of the electromagnetic disturbance conduction process simulation of intelligent components.

Design of Normal Mode Helical Antenna for Seawater Application

To overcome the substantial propagation loss in the ocean, a low frequency band should be chosen when contemplating radio wave communication.Then, the antenna used at the portable radio equipment should be very small compare to the wavelength. For the miniaturized antenna, the normal mode helical antenna(NMHA) is suitable because of achieving high efficiency. In this paper, design method of NMHA in the seawater condition (r=81, =4) is explained. The frequency bands of 100MHz and 15MHz are selected. The self-resonant structures are determined based on the theoretical equation. Electrical characteristics such as resonant frequency, input impedance, VWSR and antenna efficiency are obtained through simulation by FEKO simulator. Electromagnetic simulation model is formed by taking into account the practical experimental condition. At 100MHz and 15MHz, resonances are ensured for antenna diameter lengths of 6.83 cm and 12.2 cm respectively. Input resistance of 27.15and 94.14, antenna efficiencies of -14.88dB and -26.27dB are achieved at 100MHz and 15MHz respectively.

A Novel Electromagnetic Noise and Image Stripe Noise Suppression Method Between SMA-OIS Actuator and CMOS Image Sensor

In order to solve the electromagnetic compatibility (EMC) problem between shape memory alloy (SMA) optical image stabilization (OIS) actuator and CMOS image sensor (CIS), a novel electromagnetic noise and image stripe noise (ISN) suppression method is proposed in this paper. The electromagnetic interference mechanism of SMA-OIS actuator is analyzed by electromagnetic field simulation and magnetic dipole mathematical model. The CIS noise mechanism based on the readout circuit model and image signal processing (ISP) pipeline is analyzed and the ISN evaluation method of CIS is proposed. The drive frequency and ISN model is established by frequency sweep experiment through the joint experimental platform of SMA-OIS actuator and CIS. Furthermore, the random frequency modulation PWM method based on the spread spectrum principle is proposed to suppress the electromagnetic noise and ISN. The experimental results show that the state-of-the-art noise suppression method proposed in this paper can not only eliminate ISN, but also have good technical adaptability in practical applications.

Super-resolution reconstruction method of ground penetrating radar signals based on wavelet theory and its application in reverse time migration

The finite difference time domain (FDTD) method was used to solve the Maxwell’s equation to obtain the reverse time migration (RTM) of ground penetrating radar (GPR) signals, namely, the FDTD-RTM. In order to ensure that the correct numerical solution of iterative calculation was achieved, it was necessary to obtain high-resolution signals, which greatly limits the applicability of FDTD-RTM in engineering. Based on the characteristics of wavelet multi-resolution analysis, this study proposed a super-resolution signal reconstruction method to improve signal resolution, with the view to completely solving the problem of FDTD-RTM limitation caused by insufficient signal sampling using GPR. The results of electromagnetic simulation showed that the signals reconstructed by the above method were highly similar to the signals sampled with the same resolution. On this basis, reverse time migration electromagnetic simulation and physical model tests were designed. The results of both experiments showed that the under-sampled GPR signals could achieve FDTD-RTM following super-resolution reconstruction, and that the migration imaging results of the target were basically consistent with the design scheme. The signal super-resolution reconstruction method based on the wavelet theory was thus shown to successfully achieve the overall application of FDTD-RTM in GPR signal analysis.

Swarm Intelligence-Homotopy Hybrid Optimization-Based ANN Model for Tunable Bandpass Filter

High-performance tunable radio frequency (RF)/ microwave and millimeter-wave filter design is a challenging task due to the lack of a basic theory. The filtering characteristics are highly sensitive to the variation of tuning elements that are commonly modeled and achieved by optimization algorithms. However, those optimizations only provide satisfactory results with a good set of initial parameters. Such range-limited optimization algorithms generally have issues of falling into local optima, slow convergence, and cumbersome implementation. To mitigate this problem, for the first time, a topology-based local optimizer is integrated with metaheuristic global optimization algorithms in this work. We have hybridized the homotopy method with an improved whale optimization algorithm (WOA) and a gray wolf optimization (GWO) algorithm. In this work, an artificial neural network (ANN) is formulated and studied, which has twofold applications. First, ANN is used as a surrogate model to represent the time-consuming electromagnetic (EM) model in expediting the hybrid optimization process of tunable filters. Second, an ANN model is developed on data generated by the proposed optimization algorithm for predicting tunable circuit parameters at different tuning stages. The proposed ANN model-based algorithm is then applied to a fifth-order lumped-element tunable circuit and two fourth-order full-wave EM simulation models of two tunable bandpass filters (tBPFs). The calculated results out of the ANN model demonstrate a good agreement with simulation and measurement counterparts.