1.1 DEFINITIONS

A bistatic radar is a radar that uses two antennas at separate locations, one for transmission and one for reception. Usually the transmitter and receiver accompany the antennas at these locations. A variation of the bistatic radar is the multistatic radar, which uses multiple antennas at separate locations, one antenna for transmission and multiple antennas at a different location, for reception, or vice versa. Again, transmitters or receivers can accompany the antennas. Multistatic radar can use multilateration for target state estimates (i.e., target position, velocity, and acceleration). Multilateration combines simultaneous range and/or doppler data from multiple transmitter/receiver pairs having overlapping spatial coverage to estimate the target state without using range-dependent angle data.

Bistatic (and multistatic) radars can operate with their own dedicated transmitters, which are specially designed for bistatic operation, or with transmitters of opportunity, which are designed for other purposes but can be suitable for bistatic operation. When the transmitter of opportunity is from a monostatic radar, the bistatic radar is often called a hitchhiker. When the transmitter of opportunity is from sources other than a radar, such as a broadcast station or communications link, the bistatic radar can also be referred to as passive radar, passive coherent location, parasitic radar, and piggyback radar. In this book it is called passive bistatic radar (PBR), with piggyback radar used to refer to planetary exploration in recognition of their independent development. Finally, transmitters of opportunity in military...