Abstract
Conference Title: 2014 USNC-URSI Radio Science Meeting (Joint with AP-S Symposium) Conference Start Date: 2014, July 6 Conference End Date: 2014, July 11 Conference Location: Memphis, TN, USA Space vehicles that re-enter the atmosphere often experience communication blackout. The blackout occurs when the vehicle becomes engulfed in plasma produced by interactions between the vehicle surface and the atmosphere. The plasma often is concentrated in a relatively thin shell around the vehicle, with higher densities near its nose than rear. A less structured, sometimes turbulent plasma wake often trails the vehicle. The plasma shell severely affects the performance of side-mounted antennas as it alters their characteristics (frequency response, gain patterns, axial ratio, and impedance) away from nominal, free-space values, sometimes entirely shielding the antenna from the outside world. The plasma plume/turbulent wake similarly affect the performance of antennas mounted at the back of the vehicle. The electromagnetic characteristics of the thin plasma shell and plume/turbulent wake heavily depend on the type of re-entry trajectory, the vehicle's speed, angles of attack, and chemical composition, as well as environmental conditions. To analyze the antennas' performance during blackout and to design robust communication antennas, efficient and accurate simulation tools for charactering the antennas' performance along the trajectory are called for.