Active left-handed transmission line formed by lumped element and diode

Abstract

The invention relates to an active left-handed transmission line formed by a lumped element and a diode and belongs to the technical field of microwaves. The transmission line comprises an SMA (Shape Memory Alloy) joint and micro-strip lines and is formed in a mode that N stages of units are cascaded. Each active left-handed transmission line unit consists of a series chip capacitor, a radio frequency choke inductor, a bias voltage, a negative differential resistance diode, a parallel chip inductor, a metal through hole, a dielectric substrate and a metal earth plate. The active left-handed transmission line units are connected through the micro-strip lines. An anode of each bias voltage is connected with a metal wire on the top layer of the joint of the corresponding micro-strip line and a cathode of the bias voltage is connected with the corresponding metal earth plate on the bottom layer of the micro-strip line. Each bias voltage is connected with a radio frequency signal transmission part of the active left-handed transmission line through the corresponding radio frequency choke inductor. The active left-handed transmission line not only has the characteristics that the active left-handed transmission line has the advantages of wide band, small size and simple structure, is easy to match and is easy for circuit integration, but also has the characteristic of net gain, i.e. transmission amplification, and can be applied to design of an antenna, a filter, a power divider, a phase shifter, a directional coupler, an amplifier, a sub-wavelength resonator, a perfect lens and the like.

Description

technical field [0001] The invention belongs to the field of microwave technology, and in particular relates to an active left-handed transmission line with wide frequency band, small size, simple structure, easy matching and easy circuit integration formed by lumped elements and negative differential resistance diodes. Background technique [0002] Currently, based on resonant structures and dual transmission lines are two basic approaches to design metamaterials. From the similarity in the form of Maxwell's equations of electromagnetic field theory and telegraph equations of transmission line theory, it can be known that material properties can be determined by electromagnetic characteristic parameters (permittivity, permeability, refractive index and wave impedance) or transmission line parameters (impedance, admittance, propagation constant, characteristic impedance) are completely equivalently described, and can be transformed into each other. In 2000, Smith et al. pro...

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Problems solved by technology

However, since metamaterials are composed of periodic or non-periodic arrangements of artificially constructed sub-wavelength units, the impact of their losses has been a widely concerned problem.

Stockman in literature M I Stockman, Criterion for negative refraction with low optical losses from a fundamental principle of causality.Physical Review Letters, 2007, vol.98, pp.177404. and literature M I Stockman, Spaser action, loss compensation, and stability in plasmonic systems with gain .Physical Review Letters, 2011, vol.106, pp.156802. used the law of causality to prove that left-handed materials with net gain cannot be realized, which caused great controversy in the academic circle

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