BEAM STEERING CONTROL SYSTEM FOR LOW-COST PHASED ARRAY WEATHER RADARS: DESIGN AND CALIBRATION TECHNIQUES

Phase array antennas are a promising technology for weather surveillance radars. Their fast beam steering capability offer the potential of improving weather observations and extending warning lead times. However, one major problem associated with this technology is their high acquisition cost to be use in networked radar systems. One promising technology that could have a significant impact in the deployment of future dense networks of short-range X-band weather radars is the ``Phase-Tilt Radar\u27\u27, a system that uses a one-dimensional phase scanned antenna array mounted over a tilting mechanism. This dissertation addresses some of specific challenges that arise in designing and implementing air-cooled, low-cost, one-dimensional phased antenna arrays for phase-tilt radars. The goal of this work is to develop methods that can lead to reduce the cost and enhance the performance of this type of systems. Specifically, the thesis focuses on three concrete areas. The first one is on the development of a versatile low-cost beam steering system that can enable dual-polarimetric phased array radars to operate with high-frequency repetition pulses, difference pulsing schemes, and modern scanning strategies. In particular, the dissertation will present the development of critical components and describes the concept of operations of the beam steering system. The second area is to develop a calibration technique for small phased arrays. The work focused in finding the calibration settings for the array that best fit to the desired excitation. The technique provides lower random errors than conventional approaches, enabling the implementation of radiation patterns with sidelobes closer to the desired level. Additionally, the technique is extended to solve the gain-drift problem occurring in the two-way antenna pattern due to the temperature changes. The third area studies the use of mutual coupling as signal injection technique to maintain the calibration of both array and radar. Future air-cooled phased array radars will require the use internal circuitry to calibrate the aspect of the radar that tends to change over time. In particular, this work is focused on developing low-cost calibration techniques to correct the antenna gain and radar constant from effects of temperature changes and element failures