The Research And Application Of The Basic Characteristics Of Left-handed Medium

The purpose of this paper is to study the propagation characteristic and the timecausality of the electromagnetic in the Left_handed medium(LHM);at the same time, wetake advantage of the LHM into the design of the microwave device. the work that havedone in this paper will be listed in the following:First, the linear Left_handed medium be abstracted as a linear system. Then theauthor worked out the system function and the impulse response by the frequencycharacteristics of the LHM .then a method by which the author judge the propagation ofthe electromagnetic wave in the LHM whether obey the law of time causality will begiven . Taking advantage of this method the author have proved that the causality of theLHM that are homogeneous and frequency nondispersive in the whole frequency rangeor in a certain frequency band, the causality of the artificial LHM and the causality of theLHM which it’s permittivity and permeability are negative ,but one of them is frequencynondispersive ,and the other is frequency dispersive in the whole frequence range .Secondly, through the saddle point method , the author figured the wholeconversion process during which the step sinusoidal wave reaching a steady state fromanother state which the wave present when it just arrive in a given place .And thisprocess can be describe as: the electromagnetic wave perform a right_handedcharacteristics when it just arriving in a given spot; as time goes on,the electromagneticwave present the Left_handed characteristics ; the author can observe the steady sinewave which have the Left_handed characteristics only after the time which the saddlepoint arrived in the pole. the author made the result compare with the Finite differencetime domain method’s. At the sane time, the author will give out a method by which wecan calculate the ground velocity of the electromagnetic in the LHM.Finally, respectively introducing the design principle of the LHM that based on theSRR structure or that based on the ferrite .filling the rectangular waveguide with theferrite,and placing the metal line periodically in the waveguide,thus the author designeda kind of the LHM that work in the waveguide base model.in this paper, the author also place a slice of the LHM that based on the ferrite in a position of the rectangularwaveguide,and designed a isolator that have a high performance .