A quantitative analysis of how phase errors affect the beam quality of phased arrays

We report on our work to quantity the effect of phase errors on the forward gain and pointing offset uncertainty of phased array beams using a combination of simulations, from the aperture array simulator OSKAR, and measurements taken with the aperture array telescope 2-PAD. We demonstrate that for small arrays the limit in phase error is 10°, resulting in a 5% beamwidth pointing offset; while for larger arrays the limiting phase error is 25°, resulting in a 5% reduction in array sensitivity. In addition we argue that a digital beamforming system is advantageous over an analogue beamformer, due to its ability to dynamically calibrate residual phase errors in individual frequency channels, thereby drastically improving the pointing offset uncertainty and the forward gain of phased arrays.