Abstract
This thesis presents a series of wideband and compact antennas base on the magneto-electric (ME) dipole with decoupling, aiming to enhance the overall performance of in-band full-duplex (IBFD) wireless systems.IBFD technology enables simultaneously transmitting (Tx) and receiving (Rx) signals at the same frequency, improving spectral efficiency and consequently supporting higher data throughput. However, the existing antenna designs suffer from narrow bandwidth, polarization-dependent isolation, different radiation patterns for Tx and Rx, or bulky size. To address these limitations, this thesis introduces a novel ME dipole structure to deliver wideband operation, high isolation, and consistent radiation for Tx and Rx.
A wideband compact co-linearly polarized (LP) ME dipole antenna is proposed. It is formed by partially overlapped ME dipoles with the shared central part modified. The proposed antenna can achieve high inter-port isolation of over 22 dB at 1.90-2.91 GHz in a small port-to-port spacing and attain uniform broadside radiation for Tx and Rx. The isolation can be enhanced without enlarging the size, exceeding 40 dB at 2.2-2.5 GHz to alleviate the self-interference cancellation in analog and digital domains.
The design is further extended to a simultaneously co- and dual-LP configuration within a compact aperture, offering four isolated channels to further improve the spectral efficiency. It exhibits isolation of over 21 dB for every port pair and uniform radiation in a wide band for different ports. Then, a co-circularly polarized (CP) ME dipole antenna and a dual-CP ME dipole antenna are proposed. Thanks to the good inter-port isolation, they exhibit wideband, high isolation, and stable CP radiation for Tx and Rx by integrating the simple feed network with minimal structural complexity, making them attractive for satellite and other polarization-diverse applications.
Beyond single elements, the partially shared ME dipole with decoupling concept is extended to phased arrays. When integrated into arrays, the combination of close spacing, decoupling, as well as wide beamwidth at low frequencies and tilted beam at high frequencies makes it well-suited for wide-angle scanning phased array applications. One phased array provides consistent wide-angle scanning of ±75° at 13-17 GHz when serving as a Tx or Rx array with all elements excited. The other is developed for wideband co-LP IBFD phased array operation, offering good isolation and identical scanning range for Tx and Rx ports in a compact shared aperture.
In conclusion, this thesis provides a study of antennas for IBFD systems, based on wideband co-LP ME dipoles with decoupling. All of them exhibit wideband, high isolation, and compact structure, offering practical and impactful solutions for next-generation IBFD wireless systems.
| Date of Award | 2 Sept 2025 |
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| Original language | English |
| Awarding Institution |
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| Supervisor | Kwai Man LUK (Supervisor) |