An investigation of a frequency diverse array.
Doctoral thesis, UCL (University College London).
This thesis presents a novel concept for focusing an antenna beam pattern as a function of range, time, and angle. In conventional phased arrays, beam steering is achieved by applying a linear phase progression across the aperture. This thesis shows that by applying an additional linear frequency shift across the elements, a new term is generated which results in a scan angle that varies with range in the far-field. Moreover, the antenna pattern is shown to scan in range and angle as a function of time. These properties result in more flexible beam scan options for phased array antennas than traditional phase shifter implementations. The thesis subsequently goes on to investigate this phenomenon via full scale experimentation, and explores a number of aspects of applying frequency diversity spatially across array antennas. This new form of frequency diverse array may have applications to multipath mitigation, where a radio signal takes two or more routes between the transmitter and receiver due to scattering from natural and man-made objects. Since the interfering signals arrive from more than one direction, the range-dependent and auto-scanning properties of the frequency diverse array beam may be useful to isolate and suppress the interference. The frequency diverse array may also have applications to wideband array steering, in lieu of true time delay solutions which are often used to compensate for linear phase progression with frequency across an array, and to sonar, where the speed of propagation results in large percentage bandwidth, creating similar wideband array effects. The frequency diverse array is also a stepping stone to more sophisticated joint antenna and waveform design for the creation of new radar modes, such as simultaneous multi-mode operation, for example, enabling joint synthetic aperture radar and ground moving target indication.
|Title:||An investigation of a frequency diverse array|
|Open access status:||An open access version is available from UCL Discovery|
|Additional information:||Copyright restricted material has been removed from the e-thesis.|
|UCL classification:||UCL > School of BEAMS > Faculty of Engineering Science > Electronic and Electrical Engineering|
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