No abstract

No abstract

In this paper, a new radar signal modulated with a hybrid of the frequency shift keying (FSK) and the phase shift keying (PSK) signal—i.e., the FSK-PSK signal—is studied. Different phase encoding sequences are used to modulate the sub-pulses to obtain lower sidelobe levels and ensure signal orthogonality. In addition, to counter intra-pulse slice repeater jamming of specific length generated by the enemy jammer, an orthogonal waveform made of sub-pulses of equal length based on the FSK-PSK modulation scheme is designed. The simulation results show that the optimized discrete phase encoding sequence can significantly enhance the orthogonality of the sub-pulse in the FSK-PSK signal and effectively suppress the slice repeater jamming. Two algorithms are proposed: (1) the low sidelobe waveform optimization algorithm based on ADMM (LSW-ADMM); and (2) the anti-slice-repeater-jamming algorithm based on ADMM (ASRJ-ADMM). Both algorithms exhibit fast convergence speed and low computational complexity.

No abstract

In order to reduce the scan loss and also obtain higher scanning gain for a phased array, a subarray design is proposed in this study. Different from the prior works, the number of active phase shifters utilised in this topology is identical to its counterpart without subarrays, which makes it more cost-effective. To achieve this valuable characteristic, a reconfigurable beam-former is proposed to enable the radiation pattern of a subarray to be switchable to different modes for different scanning regions. The proposed beamformer is based on substrate-integrated waveguide (SIW) and featured by extremely low-loss, due to its unique working mechanism. For validation, a fully integrated subarray module consisting of a beam-former and two Yagi-Uda antennas is designed and analysed. Furthermore, in order to show the effectiveness, five subarray modules with uniform spacing are utilised to construct a complete prototype operating at 15 GHz. Measurement results of the entire array indicate that the achieved gain is 2~3 dB higher than its counterpart without the subarray, from −45°to +45°in the beam-scanning plane. Meanwhile, the scan loss is decreased from �1.45 dB to smaller than �0.9 dB. Meanwhile, sidelobe levels are also improved for scanning angles between �45°. It should be pointed out that the proposed approach is also applicable to broaden the scanning angle of phased arrays with properly selected antenna elements. Since there is no need to increase the number of active phase shifters, this subarray-based approach can be considered more economic, and is very attractive for a variety of phased array systems.