caa a22 4500 445305258 CHVBK 20180317142610.0 cr unu---uuuuu 170323e20110701xx s 000 0 eng 10.1007/s10762-011-9804-7 doi (NATIONALLICENCE)springer-10.1007/s10762-011-9804-7 Frequency Transformer: Appropriate and Different Models for a Building-up and Collapsing Magnetoplasma Medium [Elektronische Daten] [Robert Lade, Joo Lee, Dikshitulu Kalluri] The interaction of an electromagnetic wave with a time varying medium is governed by the property of conservation of the wavenumber. This property can be utilized to construct a frequency transformer. The time variation in the relative permittivity of the medium is easily produced in a magnetoplasma medium by altering the ionization level. The change of the ionization level can be produced by the dynamic control of the source of ionization. The switching-on action of the source produces a build-up plasma, whereas a switching-off action produces a decaying plasma. Simple mathematical models, however, for the two cases are different. In the case of building-up plasma, the model has to ensure the continuity of the current density and in the case of decaying plasma, the average drift velocity of the surviving electrons has to be continuous. Using these two appropriate models, the effect of the time variation of the plasma frequency as well as the background magnetic field of the magnetoplasma medium are studied. Switching off the external magnetic field for the wave in the magnetoplasma medium converts a whistler wave to a wiggler magnetic field. Similar results are obtained with an intensification of the source wave as well as frequency upshift of the whistler wave for the collapsing plasma medium. By controlling the static magnetic field parameters and the level of ionization, the frequency shift ratio can be changed and the frequency transformer becomes tunable. The principle of frequency up-shifting using plasma permits the generation of signals from easily obtainable frequency bands and upshifts them into frequency bands not easily obtainable by other methods. Springer Science+Business Media, LLC, 2011 Magnetoplasma nationallicence Time varying medium nationallicence Frequency change nationallicence Finite difference time domain nationallicence FDTD nationallicence Lade Robert Electromagnetics and Complex Media Research Laboratory, Department of Electrical and Computer Engineering, University of Massachusetts Lowell, 1 University Avenue, 01854, Lowell, MA, USA aut Lee Joo Electromagnetics and Complex Media Research Laboratory, Department of Electrical and Computer Engineering, University of Massachusetts Lowell, 1 University Avenue, 01854, Lowell, MA, USA aut Kalluri Dikshitulu Electromagnetics and Complex Media Research Laboratory, Department of Electrical and Computer Engineering, University of Massachusetts Lowell, 1 University Avenue, 01854, Lowell, MA, USA aut Journal of Infrared, Millimeter, and Terahertz Waves Springer US; http://www.springer-ny.com 32/7(2011-07-01), 960-972 1866-6892 32:7<960 2011 32 10762 https://doi.org/10.1007/s10762-011-9804-7 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s10762-011-9804-7 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Lade Robert Electromagnetics and Complex Media Research Laboratory, Department of Electrical and Computer Engineering, University of Massachusetts Lowell, 1 University Avenue, 01854, Lowell, MA, USA aut NATIONALLICENCE 700 1- Lee Joo Electromagnetics and Complex Media Research Laboratory, Department of Electrical and Computer Engineering, University of Massachusetts Lowell, 1 University Avenue, 01854, Lowell, MA, USA aut NATIONALLICENCE 700 1- Kalluri Dikshitulu Electromagnetics and Complex Media Research Laboratory, Department of Electrical and Computer Engineering, University of Massachusetts Lowell, 1 University Avenue, 01854, Lowell, MA, USA aut NATIONALLICENCE 773 0- Journal of Infrared, Millimeter, and Terahertz Waves Springer US; http://www.springer-ny.com 32/7(2011-07-01), 960-972 1866-6892 32:7<960 2011 32 10762 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer