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This work presents a printed monopole antenna with a miniature size and enhanced wideband using characteristic mode analysis (CMA). The printed monopole antenna structure comprises one vertical and one horizontal monopole, and a ground plane with a vertical extension. By connecting the horizontal monopole to the ground plane extension through a via hole, a significant enhancement in bandwidth is achieved in both lower and high bands. A 105% increment in bandwidth is achieved with the via hole compared to without it. The influence of the via hole is analyzed using CMA to provide a physical insight into the design. The proposed antenna is compact with an electrical size of 0.01 λ2, leading to a miniaturized design. [ABSTRACT FROM AUTHOR]

This article presents a method of using modal analysis to characterize the circular polarization (CP) performance of a printed monopole antenna. The radiator and feedline are positioned on the edge of the substrate and fed accordingly at the edge, and a modified ground plane is employed. The complete antenna without excitation is analyzed using characteristic mode theory to provide physical insight into its CP operation. The modal analysis proves that several nearly orthogonal modes can be generated at certain frequencies with orthogonal phase differences as well. The axial ratio (AR) corresponds to the modal analysis which proves the validity of the modal analysis. An axial ratio bandwidth from 3.1 to 6.2 GHz (66. 7%) is achieved within an S11 bandwidth of 2.6–11 GHz (123.5%). The proposed antenna is compact with stable radiation patterns, easy to design, and fabricate without inserting parasitic patches or inserting slots on the antenna. [ABSTRACT FROM AUTHOR]

In this paper, modal analysis is used as a guide to design a circularly polarized open‐slot antenna. The design proposes an open wide slot that is fed electromagnetically by a modified feedline. Both open slot and feedline are asymmetrically placed to the edge of the substrate. The complete antenna without excitation is analyzed using characteristic mode theory to provide a physical insight into its circular polarization operation. The modal analysis proves that several nearly orthogonal modes can be generated at certain frequencies with 90° phase differences. The axial ratio (AR) corresponds to the modal analysis, which proves the validity of the modal analysis. An AR bandwidth from 3.2 to 6 GHz (61%) is achieved within an S11 bandwidth of 3.2–14 GHz (125%). The proposed antenna achieves a peak realized gain 4.3 dBi of within the AR band. [ABSTRACT FROM AUTHOR]

The Theory of Characteristic Modes (TCM) is proposed as a systematic approach to antenna design to achieve the goal of finding the antenna structure with optimum broadband behavior. This theory provides a physical insight to the radiating nature of microstrip patch antennas and reduces the design optimization time. In this work, the resonant behavior of the highly radiating structure of the single U-slot rectangular patch on a single-layer εr = 4.4 substrate is analyzed using TCM. Modal analysis of this single-layer structure with different single feed excitations concludes that VSWR ≤ 2 impedance bandwidth in the order of 96% can be achieved with a single T-probe feed. Experimental results, included here, show VSWR ≤ 2 impedance bandwidth in the order of 71%. [ABSTRACT FROM AUTHOR]