The main computational electromagnetics methods used in electromagnetic simulation technology can be roughly divided into two categories: accurate algorithm and high frequency approximation method. Accurate calculation methods include difference method (FDFD), finite element method (FEM), method of moments (MoM) and fast algorithms based on MOM (such as fast multipole FMM and multilayer fast multipole MLFMA), among which the most effective method to solve electromagnetic problems of electrically large targets is multilayer fast multipole method. Generally speaking, high-frequency methods can be divided into two categories: one is based on ray optics, including geometric optics (GO), geometric diffraction theory (GTD) and uniform diffraction theory (UTD) developed on the basis of GTD; The other is based on wavefront optics, including physical optics (PO), physical diffraction theory (PTD), equivalent electromagnetic current method (MEC) and incremental length diffraction coefficient method (ILDC). PO high frequency method is widely used because of its high computational efficiency and strong adaptability to large targets.
Based on these methods, not only many forecasting simulation systems and softwares have been formed abroad, but also corresponding electromagnetic compatibility databases have been established, which can be used for: 1) electromagnetic compatibility design of various military platforms, including antenna layout design of large ship platforms, cabin electromagnetic compatibility design, electromagnetic compatibility analysis within systems, electromagnetic compatibility analysis between systems, etc. 2) EMC analysis between platforms, including EMC analysis of warship formation; 3)EMP (electromagnetic pulse) simulation, EMP effect and adaptability analysis of various carriers; 4) Analysis of electromagnetic environment in five-dimensional modern battlefield of land, sea, air and space.
At present, the main foreign commercial software is as follows:
1, EMC2000 software
This software was developed by a French company. The main calculation methods are moment method, FDTD method, FVO method (finite volume method), PO/GO method, GTD method, UTD method, PTD method and ECM method (equivalent current method). The algorithm is basically the same as the shipboard EDF (FVO is added), and their analysis functions are very close. According to reports, EMC2000 can simulate and analyze the impact of lightning, static electricity and electromagnetic pulse on the target, and can analyze complex media in time domain and calculate the coupling between holes and slots, but it has no RCS calculation function.
2.FEKO+ cable module software
The software was developed by a South African company. The numerical algorithms used are mainly MoM, PO, UTD, FEM (finite element method) and some mixed algorithms. In the new version of the software, the functions of MLFMA and Cable Mod and the time domain analysis of various pulse sources (Gaussian, triangular, double exponential and oblique pulse) are added, which can be used in aircraft, ships, satellites, missiles, vehicles and other systems. Including electromagnetic target scattering analysis (figure 1), chassis shielding effectiveness analysis (figure 2), antenna design and analysis (figure 3), multi-antenna layout analysis (figure 4), system EMC/EMI analysis, dielectric SAR calculation, microwave device analysis and design, and cable bundle coupling analysis.
3. Ansoft HFSS Software Company
The software was developed by Ansoft company in America. The main algorithm adopted is finite element method (FEM), which is mainly applied to the design of microwave devices (such as waveguides, couplers, filters, isolators and resonant cavities) and microwave antennas (Figure 5). Parameters and results such as characteristic impedance, propagation constant, S parameter, electromagnetic radiation field and antenna pattern can be obtained. The software and FEKO first entered the China market and had a certain number of users in China.
4.CST-SD software
The simulation software CST-SD(FIT, similar to FDTD) based on finite integration technology was developed by the German CST company, which is mainly used for the design of high-order resonant structures. It decomposes the complex system into smaller units for analysis through scattering parameters (S parameters), and its specific application scope is mainly microwave devices, including couplers, filters, planar structure circuits, various microwave antennas and Bluetooth technology. Fig. 6 is the result of software simulation analysis of the effect of double exponential pulse signal entering the chassis along the cable.
5. Fidelity software
The FIDELITY software developed by Zeland company mainly adopts FDTD technology of non-uniform grid, which can analyze the field distribution in complex filled media. The simulation results mainly include S parameters, VSWR (standing wave ratio), RLC equivalent circuit, Poynting vector, near-field distribution and radiation pattern. The specific application scope mainly includes microwave/millimeter wave integrated circuit (MMIC), RFDCB, RF antenna, high temperature superconducting circuit and filter, and integrated circuit.
6.IMST- imperial software
IMST-Empire software mainly adopts FDTD method, which is the standard simulation software for RF component design. Its application scope includes plane structure, connecting wire, waveguide, RF antenna and multi-port integration. The simulation parameters are mainly S parameters and radiation pattern.
7. Micro-stripe simulation software
The software was developed by FLOMERICS Company of the United States, mainly using the transmission line matrix method (TLM). The software can be used to calculate the coupling degree in the antenna arrangement of aircraft and ship platforms, analyze the threat of lightning strike, electromagnetic pulse and electrostatic discharge of electronic equipment, and assist the electromagnetic design of surface antenna, patch antenna and antenna array.
8.ADS software
This software is a large-scale comprehensive design software developed by Agilent Company of the United States on the basis of HP EESOF EDA software. MoM algorithm is mainly used, which can assist system and circuit engineers in various forms of RF design, such as discrete RF/microwave module integration, circuit component simulation, pattern recognition and so on. The software also provides a brand-new filter design, and its powerful simulation design means can realize comprehensive simulation analysis and optimization of digital or analog, linear or nonlinear circuits in time domain or frequency domain.
9.Sonnet simulation software
Sonnet is an electromagnetic simulation software based on the method of moments. It is a three-dimensional simulation tool for designing high-frequency circuits, microwaves, millimeter waves and analyzing electromagnetic compatibility/electromagnetic interference. Mainly used in: microstrip matching network, microstrip circuit, microstrip filter, stripline circuit, stripline filter, via (layer connection or grounding), coupling line analysis, PCB circuit analysis, PCB interference analysis, bridge spiral inductor, planar high temperature superconducting circuit analysis, millimeter wave integrated circuit (MMIC) design and analysis, mixed matching circuit analysis, HDI and LTCC conversion, and single-layer or multi-layer transmission line analysis.
10, IE3D simulation software
IE3D is an electromagnetic field simulation tool based on the method of moments, which can solve the current distribution problem of three-dimensional metal structures in multi-layer dielectric environment, including discontinuity effect, coupling effect and radiation effect. The simulation results include S parameters, VWSR (standing wave ratio), RLC equivalent circuit, current distribution, near-field distribution, radiation pattern, directivity, efficiency and RCS. IE3D is a very useful tool in microwave/millimeter wave integrated circuits (MMIC), RF printed circuit boards, microstrip antennas, wires and other forms of RF antennas, high-temperature superconducting circuits and filters, IC interconnection and high-speed digital circuit packaging.
1 1, microwave office software
The software is also an electromagnetic field simulation tool based on the method of moments. The microwave planar circuit is simulated by two simulators. "VoltaireXL" simulator deals with microwave planar circuits composed of lumped elements, and "EMSight" simulator deals with three-dimensional electromagnetic fields with arbitrary multilayer planar structures. "VoltaireXL" simulator is equipped with a component library, in which passive components include inductors, resistors, capacitors, resonant circuits, microstrip lines, striplines and coaxial lines. Nonlinear devices include bipolar transistors, field effect transistors and diodes. When building a circuit model, you can call out the components used. "EMSight" simulator is characterized by combining the modified spectral domain method of moments with intuitive graphical user interface (GUI) technology, which greatly speeds up the calculation. The electrical characteristics of radio frequency integrated circuit (RFIC), microwave monolithic integrated circuit (MMIC), microstrip patch antenna and high-speed printed circuit (PCB) can be analyzed.
12, ice wave simulation software
The software is a three-dimensional simulation tool for electromagnetic compatibility design/electromagnetic interference analysis of electronic products, and adopts FDTD full-wave numerical method. Applications include: PCB decoupling, radiation, grounding, via hole and discontinuity analysis, and electromagnetic analysis of microwave components, ferrite, resonant cavity and shielding box.
13, WIPL-D software
This software is a 3D full-wave electromagnetic simulation design software developed by WIPL-d.o.o Company based on MoM algorithm. It adopts the most advanced maximum orthogonal higher order basis function (HOBFs) and quadrilateral grid technology, which reduces the memory requirement and calculation time. According to reports, the software can simulate the antenna layout of the 58λ long platform of 20 1. The electromagnetic problems that can be solved by the software include: various EMC antenna designs, antenna layout problems of complex platforms, RCS calculation of complex platforms and microwave passive structure design.
14, Singula software
The software was developed by IES Company in Canada, and adopted MOM+PO hybrid algorithm. It can be used for electromagnetic analysis of antenna and antenna array, waveguide and resonant cavity, RF circuit and microwave components, electromagnetic scattering and RCS, absorption rate (SAR) and so on. , which can be used to analyze the layout of shortwave and ultrashort wave antennas on complex platforms.
15, FISC software
FISC, an electromagnetic scattering analysis software published by University of Illinois 200 1, is suitable for electromagnetic scattering analysis of missiles (Figure 7), airplanes (Figure 8), tanks, etc. The main method adopted is the Multilayer Fast Multipole Method (MLFMA). It is reported that it can solve the electromagnetic scattering problem of unknown quantity100000.
16, x patch software
The software was developed by the U.S. military, mainly using the rebound ray method (SBR), and closely combined with computer graphics technology. In the calculation, the physical optical approximation, physical diffraction and multiple reflection of direct light are considered at the same time. When calculating the first bounce, the most time-consuming thing is to determine the shadow part and occlusion part of the complex target. The software uses the hardware and software of Z-buffer technology to accurately determine these two parts. After the shadow part and the occlusion part are determined, the contribution of the direct field part can be calculated by PO. In order to calculate the multiple reflection effect, a series of parallel rays are emitted from the incident wave to the target, and the reflection and refraction of each ray on the target (or in the target) are tracked until the ray leaves the target. Ray tracing is based on the principle of geometric optics, and the field at the reflection point or refraction point is determined by geometric optics, including polarization effect, multilayer dielectric effect and so on. At the last reflection point of light leaving the target, the far-field scattering field is calculated by physical optical integration (Figure 9). The contribution of all rays to far-field scattering is superimposed, that is, the total far-field scattering field or radar cross section is obtained. Generally, for RCS calculation, the distance of 1 wavelength needs at least 10 ray. Although the method based on this software is simple in principle, it needs effective geometric CAD technology and fast ray tracing algorithm.
Personally, ansoft and CTS are used more.