Antenna design using MSC/EMAS

Finite element software has many features which made it attractive for antenna designers. In particular MSC/EMAS has special open boundary elements (which are based on Bayliss Turkel approximations) which allow the finite element mesh to be terminated with minimal boundary reflection. These elements do not penalise the complexity of the resulting matrix equation and hence there is very little additional overhead in terms of runtime and disk space requirements. Many antenna types have been successfully modelled, these range from simple wire antennas such as a quarter wave monopole, dipole, spiral and loop antennas to resonant aperture antennas such as a waveguide slot or a microstrip patch antenna. The major advantage that the finite element technique offers over the traditional method of moment techniques is the ability to include a wide range of materials. When using the aforementioned software, the users define their materials in terms of relative permittivity, permeability and absolute conductivity. These material constants may be complex or anisotropic. The complex material capability is particularly useful because many antennas have material components which have a significant loss tangent. The authors review some of these antenna models. They are: a) a quarter wave monopole antenna, of the kind used for mobile communications; b) a microstrip patch antenna fed by a "through the substrate" coaxial feed; c) a waveguide slot antenna excited by a propagating TE10 mode in the waveguide.