AAWSAP DIRD, Pulsed High-Power Microwave Source Technology, January 2010

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.

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uses a pulse transformer to charge a short section of coaxial transmission line to high
voltage. The transm ission line is charged qu ickly enough to overvolt a high - pressure
(2,000-psi) hydrogen switch, providing 120-ps rise-time pulses at about 350 kV and
2.5-ns pulse width to another 40Q coaxial transmission line, wh ich uses a point
geometry converter (PGC) to feed an antenna .
Figure 5 shows H2 with a PGC output
driving a large TEM horn. The peak
power is 2 GW, and these sources were
capable of a power supply- limited PRR
of 1.8 kHz. Using a flat-plate TEM horn
antenna, the radiated field at 10 meters
was 25 kV/m. At the AFRL, they
compare HPM sources using what is
termed a figure of merit (FOM), defined
as the field value at some distance
multiplied by the distance . Thus, for H3
the FOM is 250 kV. While developing the
H series of HPM sources, scientists Figure 5. H2 With Large TEM Horn and PGC Output
devised a means of efficiently
converting from a coaxial geometry to a parallel-plate geometry. Radiation from a coax
forms a doughnut pattern with no field on bore site, and thus the PGC was developed to
feed a more interesting antenna.
Figure 6 shows a cross-section drawing of HS with a PGC feeding a Brewster angle
window and an extended-ground-plane antenna. HS was developed using a much
smaller volume high-pressure hydrogen switch than its predecessors used; however,
with the pressures involved, personnel were isolated from the source whenever any
pressure was in the switch.
Figure 6. Cross-Section Drawing of HS With Point Geometry Converter, Brewster Angle Window, and
Extended-Ground-Plane Antenna
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