Modal Filter for Spacecraft Busbar Protection Against Ultrashort Pulses

Abstract

Protection of onboard equipment of a spacecraft against electromagnetic interference is an actual problem. One of the most dangerous effects is an interfering ultrashort pulse. The use of known devices for protection against conducted interference is hampered by a number of conflicting requirements, for example, protection of as many circuits as possible, small mass of a protective device, and the ability to function effectively for 15 years in space conditions. The protection of equipment against the ultrashort pulse, based on modal filtering is proposed. The paper presents the results of the development of a modal filter prototype with a broad-side coupling. When choosing a structure, such parameters as the maximum bus current, insulation breakdown voltage, wave impedance of the line and the duration of the interfering ultrashort pulse were taken into account. To substantiate the choice of structure, quasi-static and electrodynamic simulations were performed. The simulation results showed that the modal filter effectively attenuate the 0.45-ns ultrashort pulse by 7 times. A modal filter prototype without resistors has been implemented, which showed a greater level of attenuation of the ultrashort pulse than the resistive construction.