Radiation and modal characteristics of surface-wave array plasma antenna under terrestrial and space-plasma conditions

Understanding of modal characteristics is essential for controlling electromagnetic energy transport, field confinement, and radiation behavior in plasma antennas. However, the influence of transverse electric (TE) modes on the radiation characteristics of cylindrical radio-frequency (RF) plasma antennas remains largely unexplored. In this work, a surface-wave-sustained cylindrical RF plasma antenna operating in the 2–4 GHz frequency range is investigated using full-wave COMSOL Multiphysics simulations. The plasma column is experimentally sustained at 3–10 MHz, and the measured plasma parameters are used to validate the numerical model and determine the Drude parameters for the 2–4 GHz electromagnetic analysis. S-parameter analysis identifies multiple resonances within the operating band, with optimum impedance matching occurring at 2.67 GHz. The first four TE excitation modes are examined at this resonant frequency to investigate their influence on electromagnetic energy transport and antenna radiation performance. Results show that higher-order TE modes produce more localized electric-field and power-flow distributions, leading to enhanced gain and directivity. Far-field radiation patterns exhibit mode-dependent variations in beamwidth and angular power distribution associated with differences in modal field distributions. The validated plasma model is further extended to a magnetized space-plasma environment. Compared with terrestrial conditions, the magnetized space-plasma environment produces distinct mode-dependent changes in gain, beamwidth, and sidelobe structure, including a reversal of the modal peak-gain dependence. These findings provide a comprehensive framework for understanding TE-mode propagation in cylindrical plasma antennas and for optimizing array plasma antennas for terrestrial and space communication applications.