The primary job for surveillance radars is to continuously scan a specified volume of space searching for targets of interest. Radar systems that use the same antenna for both transmitting and receiving are called monostatic radars. Bistatic radars use transmit and receive antennas that are placed at different locations. The radar cross section (RCS) σ is a function of the target size, shape, and material and can be used by the radar as a means of discrimination. Radar RCS usually fluctuates over a period of time as a function of frequency and the target orientation with respect to the radar. As indicated by the radar equation, the receiver SNR is inversely proportional to the radar losses. Transmit and receive losses occur between the radar transmitter and antenna input port, and between the antenna output port and the receiver front end, respectively. The radar receiver is normally mechanized as a series of contiguous range gates. Each range bin is implemented as an integrator matched to the transmitted pulse width.