Reduced Height Waveguide Limiter Using Nanotube Technology

The solid state semiconductor technology in radar systems supporting the U. S. Army's ballistic missile defense program increases its vulnerability to the effects of high power, fast rise-time EMP, HPM, and UWB pulses. Recent research has shown that using carbon nanotubes (CNTs) can greatly improve the performance of a limiter. Improvements upon a previous X-band waveguide plasma limiter can be made by utilizing arrays of CNTs in a reduced height waveguide. This configuration offers several advantages over the current device. First, the CNTs offer greater field enhancement and survivability compared to metallic point electrodes, resulting in a faster reaction time, lower spike leakage, and greater reliability. Second, the reduced height waveguide will increase the electric field across the spark gap, which will also decrease the reaction time and reduce the spike leakage. Third, the use of CNT arrays allows the field enhancing electrodes to be present over the entire width of the waveguide on both of the H-plane surfaces without introducing significant insertion loss, leading to a reduction in flat leakage. Using a CNT array as a field enhancing electrode in a plasma limiter promises to offer faster reaction time, higher power handling capability, and greater reliability than existing systems.