Software/EDA Channel

Deeper Insight Into Antenna Radiation Fundamentals: FEKO Suite 6.2

EM Software & Systems-SA (Pty) Ltd.

FEKO is a product that is known for its analysis of complex electromagnetic radiation and scattering problems, such as antenna design, antenna placement, electromagnetic compatibility studies, bio-electromagnetics or component design. It provides a wide range of computational electromagnetics (CEM) solution methods with all license versions, making it well suited to the analysis of a wide range of CEM problems. All CEM solution methods have application strengths and weaknesses, which are overcome in FEKO by providing different solver technologies and by hybridization of these solution methods. In effect, a user may apply different solution methods simultaneously to solve different areas of a single complex problem, applying each method in its particular area of strength and avoiding its weaknesses. FEKO Suite 6.2 is the latest version of the product and builds on this legacy with the release of various new tools that provide more modeling flexibility and deeper insight into EM radiation problems.

Figure 1

Figure 1 Characteristic modes one to four for a vehicle.

Characteristic Mode Analysis

Characteristic modes describe the current distributions and radiation characteristics of an object like an antenna, in a similar way that waveguide modes describe which propagating modes are supported for a particular guiding geometry. FEKO Suite 6.2 characteristic mode analysis (CMA) thus provides antenna designers with information on what type of radiation can be supported by an arbitrary geometry.  This information extends to representations of the current distribution for each radiating mode, as well as near field and far field radiation that this mode contributes to the total performance of the antenna (see Figure 1). Antenna designers are thus empowered to design new antennas based on in-depth knowledge of the structure’s radiating properties, rather than on educated guessing or brute force optimization-based design methods.

Fast Array Solver

The Domain Green’s Function Method (DGFM) forms the mathematical basis of the new solver for large, finite sized arrays that was introduced in FEKO Suite 6.2. The fast array solver provides an optimal way of modeling very large finite arrays, with computational complexity (memory and run-time) that scales relative to the size of a single element of the array, rather than relative to the size of the entire array.  A powerful feature of the solver is that it does not require any particular structure or pattern in the placement of array elements and all array elements can be placed arbitrarily. CADFEKO also presents tools that enable the simple setup of such large arrays, including placement of elements and feeding of each element.

Higher Order Basis Functions

The heart of FEKO is still integral based formulations to Maxwell’s equations, in the form of the Method of Moments (MoM) and Multilevel Fast Multipole Method (MLFMM). The MoM formulation was strengthened in FEKO Suite 6.2 with the introduction of higher order basis functions (HOBF). HOBF bring a wealth of possible uses, which is much coarser surface meshing for solutions of equal accuracy to the finer meshed solutions of previous versions of FEKO. Alternatively, solution accuracy may be improved without remeshing a coarse mesh by simply increasing the order of the solution.

Figure 2

Figure 2 Schematic layout of cables in a vehicle in CADFEKO.

Cables in an EM Environment

Modern antenna designers cannot merely design antennas in isolation – they have to be aware of the impact that their antennas will have on the environments where they will operate and vice versa.  One such aspect that FEKO is well suited to investigate is the interaction between antennas or unwanted radiating devices and cables. This can be either where radiation couples into cables (a cable irradiation problem), or where cables radiate energy that couple into external structures (a cable radiation problem) or, of course, the combination of the two. FEKO’s technology supports the investigation of such problems via a wide range of technologies, including a unique implementation of a formulation that combines the MoM with Multiconductor Transmission Line (MoM/MTL) theory. The CADFEKO interface also supports the setup of various cable types and combinations of these to form cable bundles that may be distributed in various environments. In addition to the existing cable types (such as ribbon, coaxial, etc.) the FEKO Suite 6.2 solver now also supports twisted pair cables and the GUI helps users bundle cables with an “auto-bundle” feature and a new schematic view to connect cables in complex configurations (see Figure 2).

FEKO Suite 6.2 introduces new features to the product’s existing suite of solutions and also builds on existing methods to improve them even further. The product has a wide range of applications and will continue to improve on solver methods and the range of applicability of the product in the future.

EM Software & Systems-SA (Pty) Ltd.,
Stellenbosch, South Africa
+27 21 831-1500

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