Coupled oscillator based agile beam transmitters and receivers: a review of work at JPL

This is a review of the work done at Caltech's Jet Propulsion Laboratory during the past decade on development of the coupled oscillator technology in phased array applications to spacecraft telecommunications. First, some historical background is provided to set the work in context. However, this is by no means intended to be a comprehensive review of all work in this area. Rather, the focus is on the JPL contribution with some mention of other work which provided either insight or motivation. In the mid 1990s, R. A. York, and collaborators proposed that an array of mutually injection locked electronic oscillators could provide appropriately phased signals to the radiating elements of an array antenna such that the radiated beam could be steered merely by tuning the end or perimeter oscillators of the array. York, et al. also proposed a receiving system based on such oscillator arrays in which the oscillators provide properly phased local oscillator signals to be mixed with the signals received by the array elements to remove the phase due to angle of arrival of the incident wave. These concepts were viewed as a promising simplification of the beam steering control system that could result in significant cost, mass, and prime power reduction and were therefore attractive for possible space application. The initial work at JPL was largely theoretical and, in collaboration with York and Maccarini, Pogorzelski developed a linearized formulation of the analysis of such arrays that provided considerable insight into the dynamic behavior of the aperture phase as a function of oscillator tuning. The key results (and limitations) of this theoretical work and their implications for array performance are reviewed here. Subsequently, several experimental arrays were designed, fabricated, and tested. These arrays are described and the salient experimental results are outlined. The body of work described has brought JPL from mere awareness of the concept a decade ago, through development of several experimental transmitters and receivers based on the concept, to the brink of a current effort to integrate the transmit and receive functions in a single unit to be developed for future fight application