Wideband air-filled waveguide antennas

You, Qingchun ORCID: 0000-0001-5123-3240 (2025). Wideband air-filled waveguide antennas. University of Birmingham. Ph.D.

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Abstract

High-gain antennas play a crucial role in point-to-point and point-to-multipoint communication systems. In applications such as microwave backhaul, satellite communication, and radar systems, air-filled hollow waveguide array antennas have become a mainstream choice due to their low loss and high-gain characteristics. Meanwhile, dual-polarized antennas, with their ability to provide polarization diversity and enhance channel capacity in multipath fading environments, are pivotal in point-to-point communication systems. In satellite communication on-the-move systems, dual-polarized antennas enable arbitrary linear polarization, allowing for more effective tracking of the satellite's polarization state. This PhD thesis focuses on the design and performance optimization of dual-polarized, multiband co-aperture, and ultra-wideband waveguide array antennas. The primary contributions are as follows: (1) Present a compact corporate-fed dual-polarized array antenna: By implementing a novel one-to-one excitation method for individual radiating elements, this design effectively addresses the trade-offs between bandwidth, grating lobes, isolation, and cross-polarization performance in wideband dual-polarized arrays, significantly enhancing the overall antenna performance. (2) Present an innovative dual-mode back cavity design: This design operates in TE120/TE210 and TE140/TE410 modes and incorporates a diamond-shaped radiation slot, greatly improving the radiation bandwidth and pattern stability. Using SLA 3D printing technology followed by copper plating simplifies the manufacturing process, resulting in a compact and high-performance antenna array. This design achieved a 30.2% impedance bandwidth with high aperture efficiency and is the first to realize a 3D-printed dual-polarized array antenna with bandwidth exceeding 30%, fully covering the Ku-band satellite communication range of 10.7–14.5 GHz. (3) Present a unique dual-band, dual-polarized, shared-aperture waveguide array antenna design method: This method features a flexible frequency ratio design, catering to diverse application scenarios. An example design covering the K- and Ka-bands was fabricated and tested, making it the first planar array antenna to meet the Ka-band satellite communication transceiver bandwidth requirements (Rx: 17.7–21.2 GHz, Tx: 27.5–31 GHz). (4) Address the challenges in ultra-wideband antenna array design: By introducing an innovative design approach, this work achieves high aperture efficiency and a low-profile structure while effectively minimizing grating lobes. The ability to cover multiple frequency bands makes it particularly suitable for modern satellite communication and point-to-point microwave backhaul systems. This design achieves an unprecedented 105% fractional bandwidth with a profile height of just 0.3λ, representing a significant breakthrough in ultra-wideband antenna array technology. (5) Prevent a sub-terahertz corrugated horn fabricated using Micro Laser Sintering (MLS) metal 3D printing. A 45° inclined corrugation enables vertical printing without support, preserving circular symmetry and achieving >36 dB XPD. The integrated rectangular-to-circular waveguide transition enhances compactness, while optimized gold plating reduces ohmic loss. This is the first high-performance 3D-printed metal corrugated horn beyond 100 GHz, offering a new fabrication approach for millimeter-wave and terahertz applications.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

Supervisor(s):