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This Defense Intelligence Reference Document (DIA-08-0912-005) is dated 28 January 2010. The Defense Intelligence Agency's Defense Warning Office prepared it under the Advanced Aerospace Weapon System Applications Program. It gives an overview of pulsed high-power microwave sources and the technologies needed to build them, including insulation, cathode materials, high-voltage switching, pulse generators and antennas. The paper concludes that progress requires better cathodes, switching and insulation, and that compact ultrawideband antennas will remain difficult to build.
From the source:Release of 2026-09-18 Incident: 1/28/10, Las Vegas, Nevada. Released with redactions. This document is a Defense Intelligence Reference Document (DIRD), a technical reference format used by the Defense Intelligence Agency (DIA) to capture baseline knowledge on a specific topic for later analytic use. DIRDs are best understood as reference and synthesis products rather than as original research. It is one of 38 DIRDs produced under the Advanced Aerospace Weapon System Applications Program (AAWSAP) between 2009 and 2011. Because AAWSAP’s scope permitted a broad range of supporting topics, not every DIRD in the series directly concerns aerospace systems or future threat assessment. The following summary reflects the DIRD’s scope and framing at the time of writing and should not be read as implying current validation of the concepts discussed. This DIRD surveys pulsed high-power microwave (HPM) source technology and argues that such systems remain of military interest because they can disrupt or damage electronic systems with short, intense electromagnetic pulses. The report reviews the main source types and the supporting technologies they depend on, including high-voltage insulation, switching, cathode materials, antennas, and pulse-power generation. It emphasizes the difficulty of building systems that are compact, efficient, and practical to field, since short pulse durations, antenna size, heating, detectability, and beam or signal quality all impose hard engineering limits. Its overall conclusion is that the technology has significant potential military value, but that further progress depends on advances in cathodes, predictive modeling, high-speed high-voltage switching, and low-loss insulation, while compact ultrawideband systems will remain difficult because of basic physical constraints on antenna design.
__ _ UNCLASSIFIED//re1t Offl@IAL lel§li 8PUs:lf THE GEM II HPM SOURCE The GEM II source was based on PCSS switch technology using GaAs bulk avalanche semiconductor switches (BASS). GEM II was built by Power Spectra, Inc., in the mid- 1990s and was evaluated by the AFRL. The source was built from individual modules, each containing a rectangular horn output with a BASS switch at the feed point. The modules were assembled in a 12 x 12 array to form a planar radiator measuring 1.6 x 1.6 x 0.85 meters. By timing the switch ing sequence of each BASS module, the beam was steerable up to 30° off center. The HPM output reached 22 kV/mat a distance of 75 meters and was capable of repetition-rate operation at 3 kHz. The rise time of each module was about 200 ps, and the pulse width was about 2 ns. The major problem with GEM II was switch lifetime; typically, a few switches failed during each burst. THE JOLT HPM SOURCE The Jolt, shown in Figure 10, was designed especially to feed the half-IRA antenna. The AFRL refers to this source as hyperband, meaning the frequency band ratio is greater than 10. On the pulsed-power end, Jolt uses a dual-resonant transformer operating at 1.1 MV. The transformer charges an intermediate capacitance discharged by an oil insulated peaking switch at the focal point of the half IRA to two flat-plate transmission lines terminated at the edge of the dish. The voltage rate of rise is 5 x 10 15 V/sec, and the repetition rate is a maximum of 200 Hz. The radiated electric field waveform recorded at 85 meters is shown in Figure 11. The half-power point frequencies are an upper frequency of 2 GHz and a lower frequency of 30 MHz. 8104 6104 2" 4104 ~ -0 iii 2 101u:: ·~u "' 0r;:1 - 2104 I I I I ---L---L- 1 I I I I I ---,-I --,-I 1 I I I I I ---1----1-- 1 I I I I I I I I I I I I I I I I --~ --~ ~' -~ _t_ ---r--- r - 1 I I I I I I I I I I I -L-- -L---L---L--- 1 I I I I I I I I I I I I I I I ---,---, ---,---,1 I I I I I I I I I I I 1----1----1----1---- 1 I I I I I I I I I I I I I - r - - - r ---r - -- r - - - 1 I I I I I I I I I I I -41Q4 +-,-,~...,...,....-.-1i-.-.-..-,-1,~,..,.+~-,-1-,~.,...,l1-,-,-......-1 -1 10- 9 0 1 10- 9 2 10- 9 3 10- 9 4 10- 9 5 10-9 6 10-9 Ti me (sec) Figure 11. Jolt Radiated Electric Field Waveform at Figure 10. Jolt Hyperband HPM Source 85 Meters MESOBAND SOURCES The AFRL has defined mesoband or moderate band sources as those with a bandwidth ratio between one and three. These sources usually generate HPM energy between 50 and 900 MHz. They are designed using two techniques. The first is to feed a damped sine wave onto a wideband antenna. The second is to switch a transient pulse onto a resonant transmission line connected to a wideband antenna. One such system at the UNCLASSIFIED/ / FO lil QFFI EI>~ 11 &:li OIIL¥ 24
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