Dynamic measurement of radar cross sections

The measurement of the radar cross section of full-size targets in flight presents some unique problems. The techniques employed to maintain the dynamic range of the signal, facilitate data handling, and control the target aspect, all contribute to the efficiency with which the requisite data may be gathered and reduced. The approaches taken in solving these problems are discussed in connection with the U. S. Naval Research Laboratory (NRL) dynamic measurement radar. This system is specially designed for simultaneous pulse-by-pulse measurements at L, S, and X bands permitting a high degree of polarization flexibility. Data reduced from film records, when combined with program-derived aspect information, enables a graphical description of radar cross section to be plotted as a function of target aspect. Data from measurements of a C-54 aircraft have been plotted in this manner and show the variation of σVV, σHH at L and S bands, and σVV, σHH, σVH, σHV, σRR, σLL, σRL, σLR at X band. Operating experience with this system indicates the practicability of performing dynamic measurements.