A SIAR Transmitting Waveform Design Approach Based on Positive and Negative Sequential Carrier Frequency Coding*

The traditional sparse-array synthetic impulse and aperture radar (SIAR for short hereafter) are designed to utilize multiple orthogonal frequency signals to synchronize the isotropic radiation. The receiving terminal (such as air-borne and land-based remote sensing applications) uses a single antenna to receive signals and carries out pulse synthesis, but in general, the angle and distance detection are prone to coupling in the synthesis process due to their intrinsic nonlinear properties in the sense that the detection phase are determined by both the distance and angular. To mitigate the aliasing artifacts and weaken the coupling, the classic approach is to set the frequency coding of the transmitting signal at random points. However, these methods can only reduce its coupling to some extend, rather than eliminating it, due to existence of multi-peaks. In order to provide a remedy, we suggested in the current work a design method of SIAR transmitting waveform based on positive and negative sequential carrier frequency coding. The strong coupling between the angle and distance of SIAR radar can be readily solved by designing the encoding modes of the transmitting waveform. The simulation results showed that this method can effectively remove the angle-distance coupling of SIAR radar, and significant improvements are achieved in terms of improving success detection ratio. It seems that in addition to providing a novel perspective of the radar detection problem where there exist strong coupling between distance and angular, the decoupling approach also paves a way to several extensions in relation to detection and guidance of array radar systems.