# Bistatic radar equation for moving objects

From my understanding, and correct me if I'm wrong, the bistatic radar equation assumes that the transmitter and the receiver are separated by a distance $L$, and that the transmitter and receiver are static, while the target is moving at a distance $R_r$ from the receiver and a distance $R_t$ from the transmitter. $$P_r = {{P_t G_t G_r \sigma \lambda^2}\over{{(4\pi)}^3 R_t^2R_r^2}}$$

Hence my question, does the bistatic radar equation is different when the transmitter, the receiver, and the target are all moving? Does the equation change only when one want to consider Doppler effect?

• Thanks for the answer. I thought the time was going to show up in the equation when changing the $\lambda$ for considering Doppler effect. Jun 29, 2017 at 15:22
• Oh I see. In that you are right but think of the scale how much in practice $\lambda$ actually changes. If the target moves at 10km/sec, a very fast target, then it is only about $2\times 10/(0.3\times 10^6)$, or maybe ~6o ppm, and it is completely negligible when compared to any other effect. Jun 29, 2017 at 16:03
• and note too that if you are concerned about the the frequency dependence of the Friis's equation then you should not use antenna gain in it because that is also frequency dependent for a given aperture $A_{eff}$: $G \sim \frac{4\pi A_{eff}}{\lambda ^2}$ Jun 29, 2017 at 16:54