Abstract:

According to the characteristics of the missileborne synthetic aperture radar （SAR）platform with high speed, curvilinear trajectory and high squint angle, this paper gives a detailed analysis of the main factors should be considered when designing the pulse repetition frequency (PRF) of a spotlight SAR seeker, such as the range and azimuth unambiguous constraints, and the effect of the eclipsing and the nadir returns. It also deduces a simple formula of the maximal instantaneous Doppler bandwidth of echo signal based on nonideal movement radar platform and squint modes. And the bound of the pitch flightpath angle is achieved to assure the nadir returns can be neglected too. Then, an exhaustive method to design the PRF for a spotlight SAR imaging seeker is proposed, which avoids the range and azimuth ambiguities, and achieves minimal PRFs to acquire the returns from the main beam footprint without blind regions. The correctness of the analyses and the validity of the method are demonstrated using a simulated trajectory for a spotlight SAR imaging seeker.