Element-Rotated and Multi-Beam Antenna Array Design for Wireless Communications
- Publication Type:
- Thesis
- Issue Date:
- 2023
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Antenna arrays play a significant role in many aspects of our lives, including wireless mobile communications, sensing, radio astronomy, etc. Researchers worldwide have developed many array pattern synthesis methods over the past decades. Most of them optimize both the excitation amplitudes and phases to achieve better performances, consequently increasing the complexity and cost of the beamforming networks. To facilitate simplified feeding networks, this dissertation presents several novel array synthesis methods that can be categorized into two parts.
The first part develops an antenna rotation technique. The rotation of an antenna can be regarded as approximated amplitude weighting to its co- and cross-polarized components. By properly rotating antennas in an array, favorable radiation patterns can be achieved. Specifically, a novel approach to synthesizing sum-and-difference patterns by rotating dipole antennas and adjusting their positions with linear arrays is first presented. Then the element rotation technique is extended to synthesize shaped patterns for linear and planar arrays considering mutual coupling. After that, the element rotation technique is further extended to deal with cylindrical conformal array synthesis. These approaches replace the traditional excitation amplitude weighting with the rotation of antennas for array synthesis, which significantly reduces the complexity and cost of the beamforming networks.
The second part of this dissertation focuses on multi-beam array synthesis. As a key technology for the fifth-generation (5G) wireless communication networks, multi-beam antennas have drawn increased attention recently. A phase-only method based on a partitioned iterative Fourier transform (PIFT) method is presented to efficiently synthesize multi-beam patterns for uniformly spaced phased arrays. To achieve accurate beam control, the PIFT integrates a partitioned beam calibration strategy to calibrate the multi-beams individually without affecting each other. Additionally, multi-beam synthesis by utilizing the generalized joined coupler matrix (GJC) is presented. The GJC matrix is a recently developed matrix that can generate independently and individually scannable multi-beams using low-power-consumption and cost-effective analogue feeding networks. However, similar to other matrices, the lower beams will significantly distort and even split when they approach an upper beam. In this dissertation, an effective strategy of using reconfigurable directional couplers is adopted to address the beam splitting and to achieve continuously scannable multi-beams with a flexible synchronized optimization strategy.
Since modern wireless communication systems are evolving to be high-integration and low-cost ones, it is believed that the developed techniques could be highly attractive for numerous applications in both current and future terrestrial and non-terrestrial wireless communications.
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