Low-Noise Plasma Antennas - Practical Noise Power Measurements

Plasma antennas [1] have been of enduring interest to plasma scientists and RF engineers since the first US patent was issued in 1919 and early investigations in the 1960s. Plasma antenna advantages include the ability to turn it on and off, frequency and radiation pattern tunability, and reduced cross-coupling among array elements. Potential disadvantages include lower gain and efficiency due to the high ohmic resistance and high Johnson-Nyquist thermal noise [2] due to the high electron temperature in steady-state plasmas.

Recently the gain of a tunable plasma antenna was measured, and a regime where the gain is only slightly below that of a reference metallic antenna was demonstrated [3]. In this work, a concept of reducing the thermal noise of plasma antennas by sustaining the plasma with repetitive RF pulses is discussed. We also present the application of measurements borrowed from RF practice to characterize the noise at the terminals of a plasma antenna. The methods, challenges, and initial results are discussed.

[1] T. Anderson, Plasma Antennas. Artech House, 2011.

[2] T. R. Anderson, IEEE Int. Symp. Electromagn. Compat., vol. 1, pp. 498–501, 2002.

[3] V. Podolsky, A. Semnani, and S.O. Macheret, IEEE Transactions on Plasma Science, Vol. 48, No. 10, 2020, pp. 3524 – 3534