Advanced Waveform Generator For Integrated Phased Array Testing
Authors: David S. Fooshe, Kim Hassett, William Heruska, John Butler, Patrick Fullerton
Most antenna measurement systems are designed to acquire and process amplitude and phase data from a transmitting or receiving antenna in order to determine the antenna pattern, gain, sidelobes and other parameters of interest. The antenna under test (AUT) is typically assumed to have fixed operating parameters, except in the case of phased arrays with beam-steering capabilities. These phased array antennas are capable of changing the antenna transmit and receive characteristics under program control and present a unique challenge for the designer of antenna measurement systems. A key requirement for phased array antenna testing is that the RF stimulus and receiver measurement interval must be coordinated with the AUT timing and control commands. Optimization of this measurement process requires the measurement system to be capable of interfacing directly with the AUT beam-steering computer (BSC) in order to coordinate the various timing and control signals.
This paper will discuss a highly customizable and integrated waveform generator (WFG) subsystem used to coordinate the phased array test process. The WFG subsystem is an automated digital pattern generator that orchestrates the command and triggering interface between the NSI measurement system and a phased array beam steering computer. The WFG subsystem is controlled directly by the NSI 2000 software and allows the test designer to select and generate a sequence of up to sixteen unique synchronized timing waveforms. Test scenarios, results and data for the WFG subsystem will be presented along with plots showing the key timing characteristics of the system.