Graphical representations of radiation patterns of phased arrays using digital phase shifters

With advances in technology, the idea of using phased arrays in communication systems grows rapidly. Like conventional antennas, their radiation patterns are usually displayed as pattern cuts versus frequency. However, it is desirable to add a new parameter, the scan angle. The resulting representation shows a better overview of the overall behaviour of the antenna. Such a representation, a two-dimensional colour plot (2D-colour plot), has previously been used for fixed-beam antennas to show their radiation patterns over half-space. We use 2D-colour graphical representations to visualise radiation patterns of phased arrays employing digital phase shifters. Phase quantisation effects are clearly and quickly identified over the antenna operating range. A software program based on simple array theory has been developed. Graphical investigations of the radiation characteristics versus the number of phase shifter bits, over scanning and frequency ranges were carried out. Results were obtained for linear arrays of 64 point sources with half-wavelength spacing.