The Radiation Pattern and Phase Center of Two-Dimensional Apertures

Two matching techniques namely linearly tapered and multistep transition were used to design two dimensional radiators between parallel plate regions and 50 microstrip feed line. Transitions for different aperture widths were designed at 2.45GHz, by using a full wave simulation software. As these radiators are not point radiators, they may cause phase errors. In this study, a simple method is suggested to estimate the phase center of the radiating apertures and reduce the phase errors. The suggested method is based on the phase equally in the broadside direction and at another constant angle. The study has been carried out by using a full wave simulation software. The results show that there is almost no phase error over the range of angles of interest for the estimated phase center at the design frequency. The position of the phase does not vary with the distance from the radiator, which means that there are no phase errors as the distance from the radiator varies. Although there is some phase errors as the frequency is decreased or increased, these errors are not significant over a wide band of frequencies. For the multistep transition it is observed that the position of the phase center is closer to the center of the radiator aperture, for the wide apertures. Keyword: Phase center, parallel plate, two dimensional radiation, far field region