TABLE OF CONTENTS In the previous chapters we had studied the various types of radar waveforms. These include the linear frequency modulated (LFM) waveform central to frequency modulated continuous wave (FMCW) radars and chirp pulse radars. We also studied an antitank missile, which uses continuous waveforms (CW) radar technology for reasons of low probability of intercept (LPI). We then studied the ambiguity functions of the various radar waveforms and their salient features. We noted that the LFM waveform, in particular, has a diagonal ridge. This ridge imparts to it Doppler tolerance essential in tracking fast targets, but the diagonal also imparts to it range-Doppler coupling which is not a good thing. In this chapter, we shall study waveform compression as applied to LFM waveforms. This technique is used in both pulse as well as CW radars. We shall then study the FMCW radar design in terms of range resolution and as to how it is affected by the sweep time, target spectral width, and receiver frequency resolution.
In the preceding sections we have seen that in order to obtain high resolutions in radars, we need to increase the signal bandwidth. This is achieved in unmodulated pulsed radars by transmitting very short pulses. However, if we utilize short pulses, we also decrease the average transmitted power and hence, the radar detection range. We therefore need to look for a method which allows us to transmit at a large average power (by using long pulses) and at the same time...
