Measurement of phase centers of rectangular dielectric rod antennas

Dielectric rod antennas of rectangular cross section are of increasing interest at mm-wave frequencies. For many applications, like e.g. densely packaged feed arrays for reflector/lens systems or electromagnetic field probes, an exact knowledge of the phase center location is required. This work describes a simple experimental method to determine the phase center of antennas by means of a phase pattern measurement and a numerical least square fit procedure. For feed antennas, the method can be adopted to the numerical aperture of reflector or lens systems. Phase center locations of various dielectric rod antennas with rectangular cross section are presented and the influence of geometrical parameters and frequency on the phase center an analysed and interpreted in detail.