  The advancement of millimeter wave and terahertz technologies have
revolutionized high speed wireless networks and precise tracking systems. These
technologies offer unique penetration capabilities in specific scenarios,
significantly enhancing the capability to investigation plasma. Recent
breakthroughs include the precise diagnosis of plasma electron density using
terahertz time domain spectroscopy and the modeling of plasma sheaths in
re-entry spacecraft through scattering matrices. Concurrently, extensive
research efforts have been dedicated to comprehending plasma's influence on
electromagnetic wave behaviors, encompassing reflection, transmission,
absorption and also phase shift. In this paper, we employ COMSOL Multiphysics
software to create an inductively coupled plasma (ICP) device, enabling the
simulation of various plasma density arrangements. Our investigation focuses on
unraveling the intricate interplay between plasma configurations and
millimeter-wave transmission characteristics. The findings underscore the
substantial impact of diverse plasma concentration arrangements on the behavior
of electromagnetic waves traversing through them. Additionally, these
arrangements endow the plasma with a discernible degree of frequency
selectivity, thus expanding our understanding of plasma behavior in novel ways.
