An efficient semianalytical algorithm for the evaluation of the field and modal excitation by a line source in a two-dimensional electromagnetic bandgap (EBG) waveguide is presented. The method allows for an accurate and efficient calculation of the near field from the source inside the EBG waveguide, as well as the amplitude of the EBG waveguide mode that is excited. The same method can be applied to a wide variety of structures, as well as other types of sources and discontinuities.

Diffraction effects on truncated periodic structures at the field operator level are examined. A physically-based approximate operator inverse of the electric field integral equation (EFIE) is used to either obtain an accurate first estimate of element currents, or as a preconditioner for a more rigorous, iterative solution. For illustration purposes, linear arrays of cylindrical elements are analyzed. The reduction in the matrix solution time that is achieved is shown. Furthermore, the physical insight into array truncation effects that the method provides is discussed.

A new type of fast method of moments (MoM) solution scheme for large arrays is developed using standard basis functions. Both fill and solve times are improved with respect to standard MoM solvers. The efficiency of the method relies on approximating the Green's function as a sum of separable interpolation functions defined on a relatively sparse uniform grid, along with use of the fast Fourier transform. The method permits the analysis of arrays with arbitrary contours and/or missing elements. Preliminary results show the effectiveness of the method for planar array elements in free space.

An investigation of planar metamaterial antennas consisting of grounded metamaterial substrates with low and/or high values of the electric permittivity and/or the magnetic permeability excited by dipole sources is presented. Their performances are characterised in terms of their capability to radiate high levels of power density in the broadside direction and to produce narrow pencil beams pointing at broadside with high directivity. To achieve a high directivity, a pair of weakly attenuated cylindrical leaky waves is excited along the metamaterial substrate; sufficient conditions are established for the existence of such leaky waves in terms of the values of the substrate permittivity and permeability. Approximate closed-form expressions are derived for the phase and attenuation constants of the leaky waves. Numerical results are given in order to illustrate the radiative features of this class of antennas and to validate the theoretical analysis. © 2007 The Institution of Engineering and Technology.

In this work, bandwidth properties of planar leaky-wave antennas made of a grounded dielectric slab covered with a partially-reflecting surface are investigated. The partially-reflecting surface is described by an equivalent shunt susceptance. It is shown that, with respect to a constant frequency-independent susceptance, the antenna bandwidth is not reduced using a frequency-dependent model, except for very specific cases. With reference to passive lossless structures, numerical examples are provided that illustrate the attainable performance and confirm the theoretical analysis.