ADVANCMENTS IN PLASMA ANTENNAS FOR SATCOM NAVIGATION SYSTEMS

Gaseous Plasma Antennas (GPAs) are devices that exploit weakly or fully ionised gas to transmit and receive electromagnetic (EM) waves. GPAs can offer several advantages over metal antennas: when the plasma is turned ON they are (i) electronically reconfigurable with respect to frequency, and gain on time scales the order of microseconds to milliseconds, and (ii) transparent to incoming EM waves whose frequency is greater than the plasma frequency. When the plasma is turned OFF, the GPA reverts to a dielectric tube with a very low radar cross-section. Thus, a GPA can potentially achieve frequency hopping electronically, rather than mechanically, and reduce co-site interferences when several antennas are placed in proximity. Moreover, the reduced interferences make GPAs suitable to be stacked into arrays that can steer the beam electronically by switching on and off the plasma array elements. These features make GPAs very promising for Satellite Communication (SatCom), especially in navigation systems (i.e., systems that provide geolocation and time information). Navigation systems, as for example the European Galileo, require improvements on the navigation antennas. This is confirmed by the growing demand to identify and implement antennas that can enhance the capability of the constellation by ensuring more robust GPS service especially in GPS-denied environments or in regions where service is inconsistent. This work presents the numerical design of a plasma dipole that works in the L-band, specifically designed for SatCom navigation systems in the framework of the Italian Space Agency (ASI) project “EPT.com – Enabling Plasma Technology towards Satellite Communications”. The study here presented combines numerical and experimental approaches. A plasma experimental characterization provided the plasma parameters to estimate the antenna performances by means of full-wave numerical simulations. The numerical model includes all the parts that are needed for the plasma ignition, and a realistic electrical design. The performances of the plasma dipole have been numerically evaluated and carefully discussed. Moreover, some considerations about the spatialization and the application of the plasma dipole to a real-life space scenario have been drawn.