Contents I. Introduction
In a conventional radar scheme without detection filtering, the range resolution is related to the temporal width of the radar pulse by the simple relation R_{3dB}={c_{0}\Delta T_{3dB}\over 2}\eqno{\hbox{(1)}}
where is the speed of light in free space and and are the 3 dB resolution and temporal width of the radar pulse, respectively. When a hard bandwidth limit is present, radar imaging with pulse having a uniform amplitude spectrum is perceived to achieve the best range resolution. The simplest pulse with a uniform amplitude spectrum across the bandwidth B is the sinc pulse. For this pulse, , so the 3 dB resolution is related to the pulse bandwidth as R_{3dB}={c_{0}\Delta T_{3dB}\over 2}={0.443c_{0}\over 2B}.\eqno{\hbox{(2)}}
While the chirped, flat-top pulse offers improved power performance, it provides a similar resolution as a simple sinc pulse after the matched filtering process [1]; hence it will not be separately considered in this work. In light of the inverse relation which generally occurs between the pulse bandwidth and the achievable range resolution, recent research effort is directed towards using UWB pulses for range detection in radar systems. Nonetheless, as bandwidth has become a precious commodity in modern communication systems, a way to circumvent the limit expressed in (2) is proved useful in high-range-resolution radar systems of various kinds.
