QUANTITATIVE MEASUREMENTS OF RADAR ECHOES FROM AIRCRAFT IX. F-51
NAVAL RESEARCH LAB WASHINGTON DC
Pagination or Media Count:
F-51 echo amplitudes, sampled at L, S, and X bands over periods of 10 seconds duration, show the marked influence of the four-bladed propeller. At favorable parts of the propeller rotation cycle, the echo from the propeller blades is generally stronger than the residual echo from the remainder of the aircraft. In cumulative distributions of echo amplitude for aspects outside the general region of broadside, the weaker echoes can be fitted with a Rayleigh distribution, but the higher signal levels, appearing about 20 of the time, are stronger than this Rayleigh distribution would predict, because of the stronger propeller echo. As a result, 10 of the time the F-51 area exceeds 2.5, 5.5, and 11 square meters on L, S, and X bands, respectively. At non-broadside aspects outside the azimuth range 70-110 degree the dominant fluctuation frequencies in the F-51 echo are caused by the periodically appearing propeller echo. In the azimuth range 70-110 degree, the propeller is rather edgewise to the radar, so that the propeller echo is relatively insignificant. Probably because of the curved fuselage and shaped air scoop, the echo in this region has about the same general behavior on all three frequencies, with the strongest echoes found at azimuths 90 and 98 degree, the latter arising from the tapered tail section of the fuselage.
- Active and Passive Radar Detection and Equipment