# Scale-down modeling for radar cross-section measurement

Scale-down models for targets are used for radar cross-section measurements of huge-size objects. Is there any upper limit to the scaling factor on downscale modeling as a $100~\text{m}$ length of target becomes $2~\text{m}$ when downscaled by a factor of $50$? Will it satisfy the results?

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What are you building? Is it going to sink ships? 100 meters is too big for a plane. Why do you need to know the radar cross section? –  gecko Mar 10 '13 at 21:31

I guess there can be some limitations. If you use a model that is 50 times smaller than the target, the wavelength for the model must be 50 times smaller than the wavelength for the target, so the frequency must be 50 times greater. The imaginary part of the electric permittivity is $\frac{4\pi \sigma}{\omega}$ (in CGS), where $\omega$ is the frequency, $\sigma$ is the conductivity. So, for example, if your target is made of copper, your model's material must have conductivity 50 times greater than that of copper, and there is no such material, as far as I know (I don't think using a supercoductive material would help). Similar (but probably less severe) problems can arise with the real part of electric permittivity, as it tends to be smaller for higher frequency.