Performance Improvement and Antenna Design of Left-Handed Material Units Based on Topological Deformations

Abstract

In this paper, by applying topological theory, we evaluate some left-handed unit structures. Based on the classification of topological deformation, the laws and characteristics of potential electromagnetic parameters are captured. The original left-handed material unit is realized by using a circular C-shaped coupling ring, whose whole size is 10×10×0.5 mm 3. Through three kinds of topological deformations, to explore the influence of topology on antenna performance, the electromagnetic parameters and left-handed characteristics of the original and modified units are compared and analyzed. For the designed handshake-shaped unit structure, simulation analysis predicts that dual-frequency, or even multi-band left-handed characteristics, can be achieved. To expand the structural performance of the handshake-shaped unit, an annular line for coupling enhancement is added inside the U-shaped structure to form an integrally coupled annular unit structure. Simulation results show that, with amplitudes of reflection coefficients of −27.1 dB and −14.5 dB, the resonance points of the improved unit structure are 3.57 GHz and 5.64 GHz, respectively. Loading the unit structure with a dual-band lefthanded characteristic, a UWB antenna is designed and analyzed in detail. Through simulation, antenna performance is most affected by interference within the range of 2.5 ∼ 5.0 GHz, which coincides with the double negative frequency band of the loaded left-handed structural unit. The notch frequency band of the designed UWB antenna, which is much wider than traditional notch antennas, is 3.62 ∼ 4.54 GHz, with a notch bandwidth of 920 MHz.

A Double-Veined Leaf-Shaped Bionic Meta-Element and Array Loading Antennas for Radiation Beam Control

“…The LHM can be obtained by overlapping the negative permittivity and negative permeability frequency band. Additionally, in [8], analysis based on TL theory and experiments show that LH characteristics can arise from the combination of series capacitance (SEC) and shunt inductance (SHI). In fact, a structure similar to Fig.…”

“…It may tear, combine, or glue the figure. That is, the structure may fracture or converge at different points, or multiple figures can be combined or glued together [8]. According to TL theory, this type of transformation will significantly change the electromagnetic properties of the structure.…”

“…Homomorphic deformation is a certain type of topological transformation whose deformation strength is weaker than that of non-homeomorphic deformation [8]. When such transformation is applied to an LH structure, the resulting meta-element inherits the prototype structure's characteristics and may obtain new features.…”

“…These inherent properties of a graphic are not affected by its shape or size. In [8] topological transformation is divided into three categories according strength: differential homeomorphic deformation, homeomorphic deformation and non-homeomorphic deformation. Among them, differential homeomorphic deformation refers to some smooth elastic deformation that maintains the current and electric field distributions, with the electromagnetic characteristics showing a continuous change.…”

Pseudospin-dependent Acoustic Topological Insulator by Sonic Crystals With Same Hexagonal Rods

“…Moreover, to realize acoustic valley Hall (AVH) states, the nonzero Berry curvature located near the valley K/Kʹ was obtained by breaking mirror or inversion symmetry, and valley-projected topological edge states were observed at the interface between two sonic crystals (SCs) with distinct AVH phases [14][15][16][17][18][19][20][21][22][23][24][25][26][27][28]. Furthermore, to mimic quantum spin Hall states in acoustics, the SCs with C 6 crystal symmetry were introduced to realize artificial pseudospins-1/2 states by hybridizing degenerate modes [29][30][31][32][33][34][35][36][37][38][39]. Generally, the observed double Dirac cones are accidental degeneracy in these pseudospin-dependent ATIs, and the sizes or shapes of rods in the SCs are different, which is still a challenge for practical applications.…”