Date of Award
2025
Document Type
Dissertation
Degree Name
Doctor of Philosophy (PhD)
Department
Electrical Engineering
Committee Chair
Maria Pour
Committee Member
Tony Gatlin
Committee Member
Patrick Reardon
Committee Member
Sarma Rani
Committee Member
Richard Lieu
Research Advisor
Maria Pour
Subject(s)
Microstrip antennas, Magnetic couplings, Electromagnetism
Abstract
When the elements of an antenna array are closely spaced, the electromagnetic coupling between them can distort the radiation patterns of the individual elements and change their input impedances, causing significant degradation in the array’s performance. Numerous mutual coupling reduction methods exist in the current literature, each of which allows array elements to be closely spaced while being well-isolated from each other. This dissertation investigates mutual coupling reduction techniques for microstrip patch antenna arrays utilizing elements that excite the fundamental transverse electric (TE) mode. First, a mutual coupling reduction method inspired by the TE-mode microstrip patch cavity model is proposed for a two-element TE-mode microstrip patch array; this method involves placing a vertically-oriented PEC shorting wall, which is physically achieved using a series of connected shorting vias, between the elements to reduce the propagation of surface waves across the antenna structure. When the elements are spaced edge-to-edge, where is the guided wavelength, a mutual coupling of -53 dB is achieved in practice, successfully validating the full-wave results. Second, a mutual coupling reduction method utilizing the inherent orthogonality between TE and transverse magnetic (TM) modes is proposed for a two-element microstrip patch array, where one patch excites the fundamental TE mode and the other excites the fundamental TM mode; under ideal conditions, the mode orthogonality perfectly facilitates the intrinsic decoupling of the elements. The TE and TM mode boundary conditions are enforced according to the respective TE- and TM-mode microstrip patch cavity models. Full-wave analysis indicates that a mutual coupling of less than -20 dB is achieved when the elements are spaced edge-to-edge. Along with the ability to more closely space the elements via the proposed coupling reduction methods, using TE-mode microstrip patch elements further allows array miniaturization in that a TE-mode microstrip patch occupies significantly less surface area than its TM-mode counterpart. Additionally, this dissertation proposes a microstrip patch antenna with modified boundary conditions that excites the higher order TE20 mode with conical radiation patterns. The full-wave analysis and measured results are in excellent agreement and reemphasize the significant surface area reduction inherent to TE-mode microstrip patches.
Recommended Citation
Adams, Matthew A., "Mutual coupling reduction techniques in transverse-electric-mode and hybrid-mode microstrip patch antenna arrays" (2025). Dissertations. 473.
https://louis.uah.edu/uah-dissertations/473