Bi- and Multistatic Radar

Biand multistatic radar are expected to benefit from their separation of transmitter and receiver that denies receiver recognition by ARM, favours covered operation by their silent receivers, has higher detection possibilities of stealthy objects and is less vulnerable to jamming. The requirements of synchronisation in a separated transmitter-receiver system are discussed. The processing in bistatic radar must include the knowledge of geometry dependencies that exist for bistatic radar in range, Doppler and S/N ratio. Different track profiles relative to bistatic radar orientation and their range-Doppler relationships are presented together with examples from the processing in different types of biand multistatic radar. The extraction of target parameters, such as position, velocity and heading could require the combination of data as a function of time and/or contribution from several systems. A discussion of tracking in biand multistatic radar is included to the end that uses simulated input to estimate parameters with comparison of different methods of estimating measurement uncertainty and the use of bistatic or multistatic radar input data. 1.0 INTRODUCTION Bistatic radar has been around since the early days of radar. Interest in bistatic radar in the post-war has been repeatedly reopened for periods of time [1]. New technological advances lead to new interest in looking at possible use of bistatic radar. Before the invention of the duplexer, two antennas were necessary, one for transmission and one for receiving. The separation of the transmitter (Tx) and receiver (Rx) is the most obvious difference between monostatic and bistatic radars. Normally, a co-located Tx and Rx are not described as a bistatic system, even though they don’t share a common antenna. As the separation becomes significant relative to the typical target range, effects that are typical to bistatic radar systems become relevant. These will be discussed in more details in the sections to follow. The entities in bistatic radar, which is the Tx, Rx and target, could all in principle be located in either surface, air or space positions and they could be moving or fixed. This leads to a large matrix of possible combinations, which of not all are of practical use or will ever be studied. Within the scope of bistatic radar as defined in this paper, the source could be a radar transmitter of full control and well synchronized to the receiver, an uncontrolled radar source often named hitchhiking radar or a source not originally made for radar use such as various types of broadcast transmissions [2][3][4][14]. An illustration is shown in Figure 1 (a) to (c). The idea of using all available sources of transmission for target localisation is shown in a futuristic multiple source co-located receiver module in Figure 2.