مرکز منطقه ای اطلاع رساني علوم و فناوري - The radar cross section of ogives, double-backed cones, double-rounded cones, and cone spheres

Abstract :

Experimental measurements have been made of the nose-on backscattering radar cross section over a range of diameters from 0.05 to 1.0 wavelengths of a series of ogives with total included nose angles of $40\\deg$ , $75\\deg$ , and $120\\deg$ ; of cone spheres with nose angles of $15\\deg$ , $30\\deg$ , $40\\deg$ $60\\deg$ and $120\\deg$ ; of double-rounded cones with nose angles of $15\\deg$ , $40\\deg$ , and $75\\deg$ ; and of double-backed cones with nose angles of $40\\deg$ . Further, a series of ogives of approximately the same diameter and with nose angles of $25\\deg$ , $40\\deg$ , $60\\deg$ , $75\\deg$ , $95\\deg$ , $120\\deg$ , $160\\deg$ and $180\\deg$ have also been measured. All the present results have been obtained using two monostatic phase-locked CW balanced-bridge model measurement radars operating at frequencies of 9 Gc and 35 Gc. For targets with maximum dimensions less than two inches, cross sections of less than $10^{-7}$ square meters at 9Gc and $10^{-6}$ square meters at 35 Gc can be measured with an accuracy of pm0.5 db. The experimental data is sufficiently comprehensive to provide qualitative explanations of the scattering mechanism in the Rayleigh and resonance regions, and to make rigorous tests of the various theoretical predictions. An extension of the physical optics theory of Adachi was found to predict accurately the echo area of the ogive, the double-rounded cone, and double-backed cone in the resonance region. The Rayleigh theory was found to be generally accurate for all the models considered. The impulse analysis of Kennaugh and Moffatt was found to be accurate for the cone sphere.