Abstract: Where a single cable conveys bidirectional RF signals and bidirectional data using a data carrying DC power signal where the RF signals and the bidirectional data carrying DC power signal are separated using frequency selective networks. Alternatively a single cable conveys bidirectional RF signals and bidirectional data using a modulated RF data signal where the RF signals and the bidirectional modulated RF data signal are separated using frequency selective networks. A array of switchable antennas where RF switching elements are integral to the antennas is connected to the single cable and is powered by and communicated with through the cable. The array of switchable antennas can be arranged to produce an interrogation field in any of one, two or three dimensions by the antennas being arranged to provide for a series of parallel spaced conductors through which currents are sequentially switched in order to produce both tangential and normal magnetic field components.