Electromagnetic simulation is more challenging for antenna design as size, frequency, and materials increase. Several solutions are provided by Altair Feko such as Method of Moments (MoM), Multilevel Fast Multipole Method (MLFMM), Finite Element Method (FEM), and high frequency techniques. Solver choice varies depending on the electromagnetic problem, electrical size, materials, required accuracy, and available computer power.<\/p>\n
Solver choice should be made starting from understanding of the problem rather than making a particular technique choice. The frequency of operation is one of the considerations since wavelength is getting smaller as frequency increases. Thus, the same physical structure can have different electrical sizes depending on frequency.<\/p>\n
Electrical size affects number of unknowns, electromagnetic coupling, memory, and simulation time. So, engineers should evaluate electrical size of their structures taking into account the wavelength.<\/p>\n
The Method of Moments (MoM) is a full-wave technique that is often used to analyze antennas and conducting structures. This method can solve for unknown currents and provide information about radiation, current distribution, and electromagnetic interaction.<\/p>\n
A single antenna or small conducting structure may be appropriate for use with the MoM when it requires detailed full-wave analysis. But as the model increases in electrical size, it becomes computationally more challenging.<\/p>\n
This aspect becomes especially important in the case of moving from one antenna to a larger array because electromagnetic interactions become many times more than with the single one.<\/p>\n
The MLFMM is supposed to improve the efficiency of full-wave analysis for electrically large problems. By organizing the electromagnetic interactions, MLFMM reduces the computational effort necessary for large models.<\/p>\n
For instance, the single broadband Vivaldi antenna is manageable in terms of computations in the traditional full-wave environment. If we increase the model to the 32-element array, then the problem becomes much harder.<\/p>\n
In this situation, MLFMM should be considered when detailed full-wave analysis is needed for the electrically large problem. Thus, the decision depends on both model size and the need to retain full-wave electromagnetic analysis.<\/p>\n
Finite Element Method (FEM) is based on the volumetric technique which involves splitting regions of interest into small elements and computing electromagnetic fields in these elements. As a result, FEM is used if the volume behavior of dielectric\/material regions is significant for the problem being simulated.<\/p>\n
Many conducting antenna problems can be addressed using MoM or MLFMM. But when the detailed behavior of complex volumetric materials has to be modeled, FEM can be used.<\/p>\n
It depends on the part of the electromagnetic behavior that has to be captured.<\/p>\n
As a structure starts to span many wavelengths, full-wave analysis might start to require heavy computation resources. High-frequency techniques will offer an alternative approach as long as the assumptions used fit the problem at hand.<\/p>\n