Search

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]

In this article, a novel double-face logarithmic spiral metamaterial (LSMTM) superstrate-inspired multiple-input multiple-output (MIMO) for fully enhanced circularly polarized (CP) antenna system is examined for 5G wireless communications. This novel double-face LSMTM superstrate acts as a planar concave-concave lens. Initially, the antenna is designed with a circular spiral patch to generate CP radiation in the frequency band of interest. Then, at a height of 6.5 mm (0.606 λo) above the MIMO antenna, which has a 0.8 mm (0.075 λo) edge-to-edge separation, the LSMTM superstrate is employed for isolation, gain, and bandwidth improvement. The proposed superstrate enhances the isolation, gain, and bandwidth of the antenna by about 32 dB, 3.47 dB, and 900 MHz, respectively. In contrast to the conventional technique of verifying operation with a simulated surface current distribution, characteristic mode analysis (CMA) is used to provide a better explanation of the proposed antenna's different modes and the creation of circular polarization. Additionally, the CMA supports the development of an effective technique that can predict whether or not the isolation can be further improved. The simulated results align with the measured results and are well adapted for 5G wireless communication devices. [ABSTRACT FROM AUTHOR]

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]

This paper describes the application of the theory of characteristic modes to excite a conducting cylinder representing the chassis of a rocket. Mode excitation is achieved by cutting H-shaped slots on the cylinder at specific locations where the maximum of modal current distribution occurs. The L-matching network is designed to match the impedance of the slots to the input coaxial cable. Finally, the proposed concept is verified during manufacturing and measurement. It is shown that the measured results are in excellent agreement with the simulation. [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]

A compact four element multi‐band multi‐input multi‐output (MIMO) antenna system for 4G/5G and IoT applications is presented in this paper. The proposed antenna is developed using the theory of characteristic modes helping in systematic design of MIMO antenna system. It consists of four L‐shaped planar inverted‐F antenna (PIFA) elements each operating at 3.5, 12.5, and 17 GHz bands with the bandwidth of 359 MHz, 1 GHz, and more than 3.7 GHz, respectively. The proposed antenna system is suitable for both 4G/5G and internet of things devices as it shows the satisfactory MIMO system performance. Good isolation characteristics are observed by implementing complimentary Metamaterial structure on the ground plane resulting in isolation level lower than −21 dB between the antenna elements. The proposed antenna is fabricated and experimental results are also presented and discussed. [ABSTRACT FROM AUTHOR]