Abstract
We theoretically study mode selection characteristics in a left-handed metamaterial (LHM) loaded into a circular waveguide. The existent modes in the circular waveguide are closely related to the radius of the coaxially loaded LHM, and a general rule that determines whether one mode can exist in the structure is given in this paper. Therefore, the modes in the circular waveguide can be controlled by adjusting the radius of the loaded LHM. For a specific, normalized boundary radius, only one mode is capable of existing in the structure. Moreover, we discuss the variation in the cutoff frequency for different modes as a function of the LHM radius. We find that the eigenfrequencies of almost all waveguide modes increase sharply when the LHM radius approaches half the waveguide radius. These properties may lead to a wide range of applications such as controllable mode microwave generators and perfect waveguide reflectors.
Highlights
A metamaterial (MTM) is an artificial medium whose physical properties are engineered by assembling microscopic structures in unusual combinations.1–3 Among MTMs, left-handed metamaterials (LHMs) with both negative permeability and negative permittivity have attracted attention in the scientific community since they were first proposed by Veselago in 1968.4–8 Researchers have studied their unique electromagnetic properties, such as the inverse-Doppler effect, reversed-Cerenkov radiation, and the negative index of refraction.5,9–12 Hollow waveguides have been widely used as a basic guiding structure in microwave, radar, and antenna technology for several decades
We theoretically study mode selection characteristics in a left-handed metamaterial (LHM) loaded into a circular waveguide
For LHM loading, the allowed modes in the circular waveguide are closely related to the radius of the coaxially loaded LHM
Summary
A metamaterial (MTM) is an artificial medium whose physical properties are engineered by assembling microscopic structures in unusual combinations. Among MTMs, left-handed metamaterials (LHMs) with both negative permeability and negative permittivity have attracted attention in the scientific community since they were first proposed by Veselago in 1968.4–8 Researchers have studied their unique electromagnetic properties, such as the inverse-Doppler effect, reversed-Cerenkov radiation, and the negative index of refraction. Hollow waveguides have been widely used as a basic guiding structure in microwave, radar, and antenna technology for several decades. Because we focus on mode variation due to LHM size inside the waveguide, we use a non-dispersive and effective-medium model to describe the electromagnetic properties of the LHM. These properties can be quickly simulated to determine whether any of them provide interesting results. Scitation.org/journal/adv eigenfrequency of almost all modes in the waveguide increases extremely when the radius of the LHM approaches half the radius of the waveguide These features may lead to a wide range of applications in controllable mode microwave generators and perfect waveguide reflectors. This paper is structured as follows: Section II presents a theoretical analysis of the dispersion relation of the LHM-loaded waveguide.
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