High Power Microwave Frequency Selective Surfaces

High Power Microwave (HPM) systems penetrate electronic equipment front ends and cause substantial damage to critical components by generating extremely high energy via a very short electromagnetic pulse. Enclosing an HPM radiating aperture with a frequency selective surface (FSS) radome presents a unique problem. The power density seen by HPM radomes is on the order of 10,000 times more than is typically seen in ordinary radome applications. Using an FSS radome for HPM applications complicates the design for two fundamental reasons. First, the FSS radome is susceptible to electromagnetic breakdown and/or arcing. Second, the FSS may distort the short-pulse HPM waveform. The main objective of Phase I is to identify novel designs for high power L-band FSS’s by carrying out detailed analysis of design concepts to assess their advantages and disadvantages in terms of bandwidth, resonance, scan volume/angle performance, power handling, thickness, weight, fabrication processes, and production cost. A prototype FSS coupon suitable for proof-of-principle experimentation shall then be fabricated and limited proof-of-principle experiments shall be performed on the coupon. A Phase II Development Plan shall then be devised based on the Phase I results. BENEFIT: The main benefit of this Phase I effort is an L-band HPM FSS radome design that achieves a desired balance between pulse shape preservation and frequency response while also maximizing the radome breakdown voltage. The design will be used to build an FSS test coupon and perform limited proof-of-principle tests that demonstrate the electromagnetic characteristics of the design at low power. It is anticipated that the HPM FSS radome developed under this effort can be scaled to frequencies above or below the L-band frequency spectrum, and can therefore be modified to accommodate HPM systems having different operating frequencies, polarizations, bandwidths, and scan volume/angle dependence requirements. Finally, although the intended use of the HPM FSS radome being designed here is as a band-pass radome, the methods used for this program could likewise be leveraged to design band-stop radomes. The purpose of an HPM band-stop radome would be one of protection against HPM weapons. BRC anticipates that the HPM FSS technology derived from this effort will have immediate potential and application for high-power pulsed radar, counter-mine and counter improvised explosive device systems, counter-electronic systems, electromagnetic interference testing, and wireless power transmission technologies.