Mitigation of Communication Blackout Arising from Plasma Sheath Formation at Plasmasonic Speeds
AdvisorZiolkowski, Richard W.
Dvorak, Steven L.
MetadataShow full item record
PublisherThe University of Arizona.
RightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction, presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
AbstractWhen a vehicle moves at plasmasonic speeds, i.e., at 10 timesthe speed of sound or more, within an atmosphere, the com- pression of the air in front of this plasmasonic vehicle creates a signicant rise in the temperature of the air region surrounding it. When the heat level becomes high enough, the gases in that region ionize and create a plasma, i.e., a medium consisting of mainly charged particles. It exhibits a permittivity that has a negative real part and permeability with a positive real part. It is consequently termed as an epsilon negative (ENG) medium. The EM waves in an ENG medium are evanescent, i.e., they are decaying elds rather than being propagating ones. When such an ENG layer consists of a large enough density of charged particles, the radio frequency (RF) electromagnetic (EM) waves radiated from an antenna within the vehicle are re ected from the plasma surrounding it; they cannot propagate through the plasma to reach a receiver on the other side of it. Similarly, EM waves from a source trying to reach the vehicle from out- side of the plasma region are also re ected and, hence, cannot reach it. Since these EM waves are unable to penetrate through the plasma region, a RF blackout situation occurs, i.e., commu- nications and telemetry signal exchanges with the vehicle are lost. This RF blackout problem puts the success of the vehicle's mission in jeopardy. Recent metamaterial research has shown that a medium ex- hibiting both a negative permittivity and a negative permeabil- ity, i.e., a double negative (DNG) medium, supports propagat- ing EM waves. The research reported in this dissertation has explored the possibility of designing and realizing a metamate- rial that has a negative permeability and a positive permittivity, i.e., a mu-negative (MNG) articial medium, that is conjugate matched to the ENG plasma. It demonstrates that when it is combined with the ENG medium, it creates an eective DNG composite medium that allows EM waves to penetrate through it. A composite MNG-ENG meta-structure is rst developed and integrated with both dipole and Huygens dipole antenna systems to demonstrate an electromagnetic solution to the RF blackout problem. The characteristics of this solution are pre- sented. However, when very thick plasma regions are encoun- tered, it is shown that this simple solution becomes inadequate. It is further demonstrated that a RF blackout solution still exists by engineering the physical and material properties of a multilayered MNG-ENG meta-structure to match it to the thicker plasma regions. Practical MNG metamaterials are de- signed based on split ring resonators (SRRs); practical ENG metamaterials are designed based on capacitively loaded strips (CLSs). Moreover, they are developed as elements whose fre- quency responses are tunable for applications when the plasma properties vary along the plasmasonic vehicle's trajectory. The propagation characteristics of EM signals through plasma re- gions with dierent thicknesses were explored when ideal and the associated practical MNG-ENG multilayer meta-structures are matched to them. It is demonstrated that a practical metamaterials- inspired EM solution to the RF blackout problem faced by plas- masonic vehicles surrounded by plasmas of various thicknesses is possible.
Degree ProgramGraduate College
Electrical & Computer Engineering