Bistatic and multistatic radar sensors for homeland security

The separation of transmitter and receiver in bistatic and multistatic radar sensors offers the system designer new and additional degrees of freedom to tailor solutions to specific applications. The receivers may be passive and hence largely immune to jamming. Passive systems that also use 'illuminators of opportunity' do not have to provide a potentially expensive transmitter. Multiple transmitters and or receivers can improve sensitivity, coverage, and importantly improve the opportunity to acquire a line of site to the target (without which detection is impossible). These advantages make this form of radar attractive for a variety of applications, many of which fit well with the needs of homeland security. Equally, however, the additional complexity of having a number of separated transmitters and receivers brings about new challenges that require careful understanding if these forms of sensors are to be routinely adopted for operational use.In this chapter the role of active and passive techniques as a support to homeland security is explored. The essentials of bistatic and netted radar are introduced which enables the relative strengths and weaknesses of these approaches to be outlined. In this way a foundation is provided against which a variety of potential applications may be explored.