A Novel Method for Sensing Local Electron Density via Measuring the VSWR of Spaceborne Antenna

The performance of an antenna is impacted by the electromagnetic characteristics of the media surrounding the antenna. Most antennas work in neutral air. However, the surrounding media for the spaceborne antenna is space plasma, which is dispersive dielectric media. It could significantly change the performance of a spaceborne broadband antenna. In the present study, a broadband dipole antenna was taken for example to investigate the impacts led by space plasma. The working parameters in neutral air and space plasma were compared. The space plasma taken into account in the present study was supposed to be time-varying dispersive media. The study revealed that the space plasma could significantly influence the antenna voltage standing wave ratio (VSWR) and the antenna impedance. For those spaceborne radars working in active mode, there was a minimum detection range which makes it hard to detect the plasma area within the range. Since antenna working parameters vary with the variation of the surrounding plasma, a method to sensing the local plasma electron density based on VSWR of spaceborne broadband antennas was proposed. The method makes the antenna system work as a plasma sensor and could complement the radar minimum detection range. The results show the good performance of the method.