Accuracy criteria for radar cross section measurements of targets consisting of multiple independent scatterers

Abstract

Abstruct-Two theoretical models for radar cross section (RCS) measurements of electrically large targets consisting of multiple independent point scatterers are developed to determine the accuracy with which sample averages approximate true average RCS. Two specific sources of measurement error are addressed. The far-field criterion is shown to depend on antenna beamwidth rather than phase planarity of the illuminating field at the target, resulting in a greatly reduced requirement for separation between radar and target. The effect of clutter on the measured signal is found by determination of the joint probability density between the target and the measurement values, and the variance of the error produced by the clutter is shown to be systematically reduced by averaging a number of measured samples.Jon N.

Multisource information fusion for enhanced simultaneous tracking and recognition

“…The scattering mechanisms included in the STAR model are for energy reflected from the ground to a target and back to the radar, energy reflected from the target to the ground and back to the radar, and energy reflected from the target to another part of the target and back to the radar. The sum of the independent RCS contributions [26] estimates the total target RCS.…”

Simplified Formulae for the Estimation of Offshore Wind Turbines Clutter on Marine Radars

“…In such a situation, the incident wave is spherical, and, therefore, the phase values of the incident wave at the surface of the body differ from the phase value at the center of the object. A widely accepted far field criterion is to limit the phase deviation in the radar receiver to be less than π /4, which means a maximum phase deviation of 22.5° in the incident wave on the object surface [ 39 ]. This condition is used to obtain the threshold distance for far field condition ( R 0 ) as a function of the lateral larger dimension of the object ( L ) and the wavelength λ [ 40 – 42 ]: …”

RangeCAD and the NIST RCS uncertainty analysis

“…Transmitting antenna gain and receiving antenna gain doubles the potential error. Assuming a cosine-squared antenna pattern and a target that is a linear array of equal-amphtude uniformly-distributed point scatterers, the RCS imcertainty [10] is -201og[(l-f-sinc(2X))/2], where sincJA = sinX/X. Here, X = where 9i is the angle subtended by the target at the antenna.…”

“…however, here we assume that the receiver is kept tuned to the transmitted frequency, which is applicable to airborne target simulation. If we also assume square-law detection, our final expression for the detected signal becomes [2,3] iV-l \Z{r)f = = |^Uxp(r -(A - 10) n=0 It may be further noted D(u) can be written as that the absolute value of the Doppler fine structure coefficient sm{N7cvTr) N sin(7ri/Tr) (A -11) where now p{y) describes the point-scatterer probability density along the target length L. The ratio 7^/70 was eliminated by forming the ratio of the measured signal to the predicted far-field response [10]. Now if the center of the target is offset by 8 y from antenna boresight and we assume a uniform point-scatterer probability density function, then {1 n(t) p^1 J-k+h G{y)dy.…”

“…In carrying out an uncertainty analysis, we separate these two effects. We set A = 0 in eq (B-8), and express in decibels the total RCS near-field uncertainty as 20 log 2 1 +smc(f|j)' (B-9) We can also express in decibels the pointing uncertainty as 20 log ( + sinc( {B - 10) This expression was obtained by subtracting the expression for the effects of both amplitude taper and pointing error from the expression for amplitude taper alone and adding unity.…”