Influence of plasma on antenna and design of tunable matching network

To solve the “black-out” problem of hypersonic vehicle, the impact of plasma on monopole antenna is analyzed in this paper with a tunable matching network proposed subsequently. The plasma sheath around the vehicle with a speed of 20Ma and a height of 60km is simulated through fluid theory to obtain the plasma distribution around the vehicle. Then, the monopole antennas with different electron concentration are discussed, which are compared with the case of free space. The results demonstrate that the center frequency and the surface current of antenna vary in different degrees for different electron concentration. Finally, to effectively improve the performance of antenna, a tunable matching network is designed by matching the impedance of the plasma and changing the capacitance of the varactors.