Reseach On Frequency Diverse Array Characteristic And Transmit Beam Control

Phased-array is widely used in radar, communication and navigation systems for the capability to steer the beam with directional gain. Compared with the conventional phased-array, the frequency diverse array(FDA) can steer the beam without phase shifters, which will save costs effectively. What’s more, FDA can provide range-angle-dependent beam which can be controlled by using frequency increment between adjacent elements. It offers a potential to design transmit beampattern and localize the targets in two dimensions in terms of ranges and angles. Based on the projects “Research on frequency diverse array” and “Frequency Diverse Array-based Wireless Communication Principle and Applications”, this thesis mainly focuses on the investigation of FDA and transmit beampattern.The main contributions of this thesis include three following aspects:(1) Different from phased-arrays, FDA uses a small frequency increment to generate an array factor that is a function of angle, time and range. Some fundamental questions of FDA are investigated in this thesis, such as resolution and frequency increment limitation. Different transmit-receive systems are proposed in this thesis with potential for 2-D target location. Range-angle-dependent beampattern of FDA provides a potential to suppress range-dependent clutter and interference, which is not accessible for conventional phased-arrays. The simulation results show that FDA has a more robust beam compared with phased-arrays via range-dependent beamfoming.(2) The thesis proposes beampattern synthesis schemes for linear FDA to focus transmit energy in one or multiple desired range-angle spatial areas with applications to locate 2-D targets or suppress interference and clutter. Furthermore, arbitrary shaped beam in a two-dimension section can be attained through the proposed method. The effectiveness is verified by comprehensive numerical simulation results.(3) Since a fixed frequency increment in basic FDA will restraints the performance improvement in different environment significantly, this thesis proposes an adaptive frequency offset selection scheme to control the transmit beam to maximize the output signal-to-interference-plus-noise ratio(SINR). The effectiveness of the proposed scheme is verified by simulation results.