Digitization of signals in phased arrays moved from the backend to the frontend in the last few decades, and this trend has been supported by a number of prototypes/demonstrators to explore the associated engineering science. The first part of this tutorial will summarize the work that the presenters have done on a number of these demonstrators over the last 15 years, briefly summarizing the calibration concepts and lessons learned with these testbeds.
The calibration and pattern measurement of large outdoor phased arrays typically requires large infrastructure for direct measurements of radiated fields, or such measurements are made indirectly using internal (nearfield measurement or mutual coupling-based) mechanisms. For many applications, especially that of large, next-generation phased array weather radars, direct far-field measurements are either preferred or demanded by the application’s scientific goals. This tutorial introduces and explores the use of calibration probes mounted on UAVs as a means to provide such a far-field measurement mechanism for these phased array systems. Dual-polarization calibration, being critical for weather radar systems, will be discussed, as well as the trade spaces involved in pattern measurements using such a platform.