Analysis of dielectric antennas by a diffraction method

Performance comparisons and assessment of the compatibility of microstrip patch antennas and leaky-wave dielectric antennas for millimeter wave communications are presented. The antennas are formed of scattering material, placed in the near field of the excitation source, and equipped with circular waveguides functioning in the fundamental mode. An integral formulation is devised for the diffraction field around the antennas with either homogeneous or composite structures. The calculations center around a singularity and are expressed by means of the Green function, which is solved by a method of moments technique involving point-segments. An approximate solution is defined for diffraction in the near field for a body of revolution, and experimental results are provided for the directivity of the radiation from a source in two planes of polarization. The calculations are applied to scattering by a dielectric body using the method of volumic equivalence, showing good agreement with experimental values, particularly when a good adaptation is made between the dielectric bodies and the waveguide source. The equivalence method is suggested to be suitable for modeling the diffraction field around heterogeneous antennas.