A system for sensing aircraft and other objects uses bistatic radar with spread-spectrum signals transmitted from remotely located sources such as aircraft flying at very high altitudes or from a satellite constellation. The first and second portions of the phase-changeable material region may contact respective ones of the first and second electrodes at respective first and second electrode contact surfaces and the third portion may have a cross-sectional area that is less than areas of each of the first and second contact surfaces. The invention has particular utility in the burn-in and other pre-packaging testing of dice to establish known good dice.