Bistatic radar

In forward scatter, the scattering can be modeled using Babinet's principle and is a potential countermeasure to stealth aircraft as the radar cross section (RCS) is determined solely by the silhouette of the aircraft seen by the transmitter, and is unaffected by stealth coatings or shapings.

However, target may vary from place to place location and tracking is very challenging in forward scatter radars, as the information content in measurements of range, bearing and Doppler becomes very low (all these parameters tend to zero, regardless of the location of the target in the fence).

It is a generalisation of the bistatic radar system, with one or more receivers processing returns from one or more geographically separated transmitter.

The receiver measures the time difference of arrival of the signal from the transmitter directly, and via reflection from the target.

This defines an ellipse of constant bistatic range, called an iso-range contour, on which the target lies, with foci centred on the transmitter and receiver.

[12] In a bistatic radar with wavelength λ, where the distance between transmitter and target is Rtx and distance between receiver and target is Rrx, the received bistatic Doppler frequency shift is calculated as: Note that objects moving along the line connecting the transmitter and receiver will always have 0 Hz Doppler shift, as will objects moving around an ellipse of constant bistatic range.

Bistatic imaging can be useful in differentiating between ice and rock on the surface of a remote target, such as the moon, due to the different ways that radar reflects off these objects—with ice, the radar instruments would detect "volume scattering", and with rock, the more traditional surface scattering would be detected.