Phase-locked loop control of antenna arrays

A phase-locked loop (PLL) can, in combination with a double balanced mixer and single sideband filter, can be used as a phase shifter operating over a wide range of frequencies. Such a phase shifter can be used in a phased antenna array and, for some applications, offer significant advantages over other beam steering techniques; they are linear, continuous, cheap, compact and very easy to control. Adjustments to compensate for antenna phase mismatches, mutual coupling and unwanted frequency scanning are possible. These phase shifters can be employed in a number of different configurations. The paper gives a brief recap of initial work published by Houghton and Brennan (see Electronics Letters vol.26, p.165, 1990, and proc. IEE-H, vol.139, p.31, 1992) and discusses the advantages and disadvantages of some of the possible configurations, the applications in which these phase shifters might be used and, in particular, the application to self phased receiver arrays