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This work presents a bandwidth enhanced high gain rectangular patch antenna operating under two similar spectrally close modes created from a TM50‐like mode in the vicinity of another higher order mode of the patch. The patch is embedded with two wide slots and meandered linkages are used to maintain current continuity. The whole structure is studied using the theory of characteristic modes and the excitation of these higher order modes is controlled to enhance the bandwidth. One of the two similar modes is very weakly excited and does not affect the antenna's performance. The beam tilting at lower frequencies are compensated by properly choosing the capacitors as phase shifter elements on the meander linkages. The antenna size is miniaturized by properly choosing the dimensions of the meander linkages and the resonant length is reduced by λ/2 as compared to that of a conventional TM50 mode supporting patch. The patch size becomes 3.35 × 4.03λ/2 instead of 5 × 5λ/2 (λ is the substrate wavelength). The coaxial probe fed structure exhibits a good performance of impedance bandwidth of 10.5% around the center frequency of 5.7 GHz with a gain variation 10–12 dBi, which appear to be better than other antennas of similar size. [ABSTRACT FROM AUTHOR]

This paper presents a compact 5G multiple‐input multiple‐output (MIMO) microstrip antenna with isolation enhancement based on a slotted complementary split‐ring resonator (SCSRR) and the theory of characteristic modes (TCMs). The metamaterial unit consists of three CSRR connected by extra slots. These added slots improve significantly the rejection response in terms of bandwidth and suppression. The dispersion diagram analysis is introduced to show the filtering characteristics of the band‐gap structure before and after adding these additional slots. The TCM is employed to investigate the behavior of this 5G MIMO antenna before and after adding the slotted CSRR. The TCM is also applied to the MIMO antenna system to build up a precise methodology that can foresee whether the isolation can be upgraded further or not. The slotted CSRR is inserted meticulously in specific locations to block the coupling modes and almost does not affect the results of the noncoupling modes to improve the isolation remarkably. With this slotted CSRR, a 27‐dB reduction in the mutual coupling between the two patch antennas is achieved. The whole design has been simulated utilizing the Microwave Studio CST ver. 18 simulator. The antenna being proposed is highly efficient and suitable for 5G wireless communication. [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]

The theory of characteristic modes (TCM) for PEC bodies is showing great promise and application in the analysis, design, and placement of antennas. Its use for input impedance estimation, however, is still largely dependent on the idealized delta-gap model. Because TCM depends on all conductors, even feed structures, care must be taken for certain classes of antennas if estimating input impedance; probe-fed microstrip patch antennas (MSAs) are one example. In this paper, two different coaxial probe feed models are developed to estimate the input impedance of thin, arbitrarily shaped, air-dielectric MSAs using TCM. Their accuracy is compared with experimental results for a case study of an L-shaped MSA. Results show the importance of including all metal structures, including feeds, in TCM analyses. [ABSTRACT FROM AUTHOR]