**Antenna analysis for electromagnetic compatibility and interference interference in Altair Feko**

Broadband antennas such as: biconic antennas, logoperiodic antennas, spiral antennas and horn antennas are widely used for electromagnetic compatibility (EMC) testing. These antennas can be effectively investigated in the Altair Feko software solution using the moment method (MoM), which generates only a surface grid on conductors and dielectrics. The radiation to infinity using the method of moments (MoM) can be accurately described without specifying special absorbing boundary conditions and additional elements in the computational grid. Adaptive interpolation of calculation results in a wide frequency band reduces the number of required frequencies for modeling. The POSTFEKO environment provides a powerful interface for visualizing simulation results, including parameters such as antenna coefficient, standing wave coefficient (SWR), reflection coefficient, antenna input impedance and gain.

**Modeling of electrically large structures in Altair Feko**

To calculate a car model using the method of moments at a frequency at which an object becomes electrically large, several gigabytes of memory may be needed. For example, at a frequency of 900 MHz, the wavelength is about 33 centimeters and about 15 wavelengths will fit on a medium-sized sedan. The multilevel fast multipole method implemented in Altair Feko allows you to solve such a model using only a few hundred megabytes of memory.

Another outstanding feature of Altair Feko is the approach to solving electrodynamic problems on car windshields, which allows modeling inclusions of arbitrary shape in a multilayer dielectric structure. Embedded or glass-printed antennas can be calculated using this method, without involving significant computing resources. Altair Feko has also implemented innovative tools for creating limited surfaces shaped like windscreens. Wires and Bezier curves can be used to determine the antenna on such a surface.

Altair Feko offers a number of methods for asymptotic high-frequency approximations, with minimal computational resource requirements. Among these methods are: physical optics (PO), ray geometric optics (RL-GO) and homogeneous diffraction theory (UTD). These methods can be combined with the method of moments (MoM) in order to solve electrically very large models with complex geometry of the components. A practical example is the analysis of a horn antenna. Initially, the problem is solved by the method of moments, and in the presence of an electrically large structure – by the method of physical optics.

To solve algorithmically complex problems, the use of high-performance computing (HPC) approaches is provided. Altair Feko solvers support parallel computing on the central processor through multithreading. MPI and OpenMP parallelism are used to improve performance when solving complex models. Altair Feko also supports accelerated computing using NVIDIA's CUDA GPU technology.

HyperWorks Unlimited Private cloud computing is a fully debugged software and hardware that provides unlimited use of software on the user's device.

HyperWorks Unlimited – Virtual access to high-performance computing (HPC) on demand anywhere. Altair Feko, certified as Intel Cluster Ready, can be used to simulate the most advanced tasks on large-scale clusters.

**Screening in Altair Feko**

Altair Feko allows you to calculate the shielding coefficient of metal or dielectric housings of arbitrary shape containing slots or other technological holes. A plane wave can be used as an external source to obtain near scattering fields inside the structure, or to induce currents in wires that must be shielded by the housing. The resulting fields can be compared with those that are present in the system without shielding by the housing and draw appropriate conclusions.

The related problem of the presence of internal sources in the system under consideration (dipoles or radiating wires) can be solved and radiated in the near or far field zone can be investigated. In addition, the imperfection of the shielding material can be taken into account through the skin effect or through the effect of electromagnetic waves penetrating into the conductive medium. Altair Feko uses a special method to calculate metal housings that have a shielding factor of 200 or more decibels.

**Cable modeling in Altair Feko**

The analysis of the electrical connection between cables usually consists of two calculations: an analysis of their irradiation from the external environment, and an analysis of their own radiation (external fields caused by currents in cables). Altair Feko allows you to analyze the electrical connection between cables based on the results of calculations of their own radiation, taking into account external radiation (interference from external fields or other cables). The Standard Transmission Line Theory (MTL) is an effective numerical electrodynamics method for modeling the electrical connection between cables and external structures. The MTL method in Altair Feko can be used for complex, arbitrary cross-sectional shapes of a bundle of cables. Other numerical methods, such as the method of moments, the multilevel fast multipole method, or the finite element method, can be applied to calculate external fields or induced currents. In those cases where the standard MTL method cannot be applied, the hybrid MoM/MTL approach implemented in Altair Feko can be effectively used.

**Usage examples**

Lightning protection and radio frequency interference immunity investigated for the Karoo Array Telescope [1] include the results obtained in Altair Feko. An indirect lightning strike was simulated using an external source of plane electromagnetic waves. The shielding of cables laid along the racks of the radio telescope to the horn, cable twisting and the effect of the difference of barriers at the base of the pedestal were also investigated. After controlling the density of surface currents at the interface between the elements of the telescope, the lightning rod was redesigned. This turned out to be necessary due to the emerging capacitive coupling, which is the cause of undesirable surface currents flowing inside the structure.

**Conclusion**

Altair Feko provides excellent modeling capabilities for electromagnetic compatibility and noise immunity problems. A special feature of Altair Feko is the specialized approaches implemented in CAD for calculating very large values of the shielding coefficient, as well as modern cable modeling methods. And this is only a small part. A whole set of numerical methods that can be used together, as well as high-performance computing approaches, ensure that even electrically large models will be solved in an acceptable time.

Altair Feko (more details) is a computer–aided design system for conducting electrodynamic modeling. Combining calculation methods in Altair Feko makes it possible to effectively solve a large number of electrodynamic and related tasks: antenna design and positioning, diffraction and scattering of electromagnetic waves, finding the effective scattering area (ESR), problems of electromagnetic compatibility (EMC), pulsed radio engineering, optics, high-intensity radiation, as well as radiation safety problems.

**Pricing, licensing and provision of temporary Altair Feko licenses**

For the provision of temporary licenses for Altair Feko software solutions, testing and purchase, please contact NanoTechProm specialists by phone +7(777) 797-89-75 or by email info@nanotechprom.kz.