Targets for Microwave Radar Navigation

T NOW seems likely that radar, developed during the war, will find increasing application as a navigational aid for aircraft and surface vessels. In fact there are good reasons for expecting that peace-time radar can be made even more efficient than its war-time prototype. There are two ways of improving radar performance. One may concentrate on the radar set proper with the object of increasing either the power of the transmitter or the sensitivity of the receiver. Or, one may take steps to improve the echoing efficiency of the targets. The latter was, of course, not possible during the war since most of the targets of interest were controlled by the enemy. It is a purpose of the present paper to consider the design of various targets of high echoing efficiency and wide angular response which may be placed at strategic points as aids to radar navigation. The ideal reflector to serve as a "beacon" or "buoy" for guiding radar-equipped aircraft or ships would present a highly effective area to incident radiation over a full 360° in azimuth, and would also be operative over a fairly broad vertical angle. The value of a particular target for navigational purposes may therefore be considered in terms of two factors: effective area, and angular response. The echo received by a radar from a particular target can be calculated by the formula: 1