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Journal of Directed Energy
Volume 6, Number 1 Fall 2016

The papers listed below constitute Volume 6, Number 1 of the Journal of Directed Energy, a special issue on Non-Lethal Directed Energy Weapons edited by David B. Law.
Print copies of this, and other issues of the Journal of Directed Energy are available through the DEPS online store.

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The Introduction to Conference Proceedings of the 2015/2016 DEPS Directed Energy Systems Symposium's Non-Lethal Directed Energy Weapons and Enabling Technologies
David B. Law; Joint Non-Lethal Weapons Directorate Technology Division

Non-lethal directed energy weapons (NL DEWs) can play a critical role in missions across the range of military operations. A number of non-lethal weapons are currently fielded to give our men and women in uniform alternatives between "shouting and shooting," while reducing the risk of significant injury to non-combatants and damage to property and equipment. These devices have been and continue to be extremely valuable to troops involved in current operations. Non-lethal capabilities are available for use in a variety of situations, from humanitarian and peace operations to combat operations. The objective of this introductory article to the Directed Energy Professional Society journal article is to highlight the Department of Defense (DoD) Non-Lethal Weapons Program; Identify NL DEW technologies that were presented in the 2015 and 2016 DEPS Weapons Systems Symposium's Non-Lethal Directed Energy Weapon Systems and Enabling Technologies conference proceedings; and introduce seven technical papers in the current issue. Each of these three objectives identifies key NL DEW technologies that potentially mitigate known capability challenges that are documented in the DoD's two Joint Requirements Oversight Council (JROC)-approved non-lethal effects Initial Capabilities Documents (ICDs). Both the 2015 and 2016 DEPS weapons systems conferences provided information related to a great number of next-generation Non-Lethal Directed Energy Weapons Systems and Enabling Technologies that are now in development by the JNLWD. Both conferences provided an overview of the currently funded JNLWP technology development efforts as they relate to the development of future non-lethal directed energy weapon prototypes as well as development of peripheral technologies that comprise the many subsystems and components of these NL DEW prototype systems. Additionally, many of these efforts work to reduce the current size, weight, power consumption, thermal management, and cost (SWAP/C2) issues that are currently associated with many of the JNLWD's NL DEW prototype designs.
PAGES 1-10

Solid-State Active Denial Using Gallium Nitride Technology
Ken Brown and Nick Kolias, Raytheon

Active denial technology (ADT) is a non-lethal weapon that induces intense thermal discomfort by heating the outer-skin layer using high-power 95-GHz millimeter-wave energy. Active denial has consistently been shown to be one of the most effective and safest non-lethal weapon systems in existence. The majority of active denial systems developed to date have been developed using vacuum electronic devices (VEDs), typically gyrotrons. Although these relatively high-power systems have effective ranges out to 1 km, they require a large dedicated military vehicle to house the source, antenna, power, cooling, and required ancillary equipment. Solid-state active denial technology (SSADT) is a smaller, self-contained, shorter-range system that can be mounted on top of a military vehicle; the original vehicle purpose and mission are preserved. SSADT is enabled with Raytheon's high-power gallium nitride (GaN) semiconductor technology. This paper explores the application of this game-changing GaN technology to active denial.
KEYWORDS: Active denial, RF directed energy, Millimeter wave, Non-lethal, Solid state, Gallium nitride
PAGES 11-24

High-Efficiency, Millimeter-Wave Combining for Solid-State Active Denial Systems
Jean-Marc Rollin and Steven E. Huettner, Nuvotronics, Inc.

High-power-density, radio-frequency energy must be delivered in a small package as a building block for deployable directed-energy active denial systems. Allowable element spacing at 94 GHz imposes difficult packaging and efficiency requirements on all components used with trades in size, power, and weight. Future directed energy systems need portable capability in order to be effective in mobile applications and therefore efficient operation is at a premium. Meeting efficiency requirements requires the lowest possible radio frequency loss, as well as efficient and stable thermal control of individual power amplifiers. Operation at 94 GHz demands tight constraints on fabrication tolerances required for optimum performance. This paper discusses an approach to improve solid-state active denial technology systems through use of a low-loss millimeter wave platform that uses PolyStrata microfabricated transitions, combiners, and antennas. The signal path and components from preamplification to transmission are modeled with performance predictions, and candidate designs and thermal management are discussed.
KEYWORDS: Power combiners, Power amplifiers, W band, Antennas, Additive manufacturing, Microfabrication, High efficiency, Solid-state active denial systems, Solid-state active denial technologies, Directed energy
PAGES 25-36

Determining Risk of Significant Injury for Active Denial Technology Systems
Shannon Foley and Wesley Burgei, Joint Non-Lethal Weapons Directorate Human Effects Office

Reversibility is a key tenet of non-lethal weapons (NLW), and risk of significant injury (RSI) (as the metric used to quantify the reversibility of human collateral effects) is a critically important system attribute. RSI for a specific system is comprised of at least two probabilities: the probability of a given dose and the probability that the dose will cause a significant injury. The probability of delivering a given dose may depend on hardware, software, and environmental factors. NLW developers must identify the necessary dose to achieve the desired effect while remaining within the bounds of acceptable injury risk. The area in between an effective dose and injury is referred to as the "operating envelope," and for active denial technology (ADT) this space is considerably large. Dose-response curves and models currently exist that can estimate, to acceptable levels of certainty, the probability of significant injury given a specified dose. The human effects characterization of ADT (including effectiveness and RSI) is sufficient enough for confidence that if the intended dose on the target is reliably delivered, then the RSI should be close to 0%. Because of the large ADT operating envelope, for current and future ADT systems RSI is most dependent on engineering features of the system design. Therefore, the RSI for any particular ADT system will depend mostly on the system's ability to control the dose delivered, that is, the system's reliability.
KEYWORDS: Active denial, Directed energy, RSI, NLW, Human effects
PAGES 37-43

Compact and Multifunctional Metamaterial-Enabled Antennas
D. H. Werner, M. D. Gregory, Z. H. Jiang, S. D. Campbell, J. A. Bossard, and C. P. Scarborough; The Pennsylvania State University

Since their inception, metamaterials have seen growing use in numerous electro - magnetics applications such as antenna miniaturization, bandwidth improvement, scattering reduction, and integrated tunable filtering. Additionally, they can be used to achieve enhanced or tailored radiation patterns in the form of side-lobe reduction, directivity improvement, multibeam emission, and minimized cross-polarization. In some metamaterial-enabled designs, the antennas themselves can be reduced in size or the functionality of an effectively larger antenna can be obtained. In other designs, the antenna remains fairly basic and alternative size-reduction measures such as lower profiles are realized through metamaterial technologies. Standard antennas such as patches and monopoles can often be used with an accompanying metamaterial to create a total system with performance beyond the antenna alone, lending to simple design and construction. In other cases, fairly complex antenna-metamaterial systems can be engineered to realize both miniaturization and multifunctionality such as the ability to tune operating frequencies or change polarization. In this paper, a design process is illustrated that uses specialized, efficient electromagnetic simulation tools and powerful global optimization strategies to create antennas, metamaterials, and metamaterialenabled antenna systems for use in a wide variety of applications. Several examples are given with simulations, fabricated designs, and measured results.
KEYWORDS: Metamaterials, Antennas, Miniaturization, Wideband, Tunable, Multifunctional, Transformation optics, Optimization
PAGES 44-67

A Dual-Frequency, Folded-Topology, Dielectric Waveguide Lens Antenna
Randy D. Curry, Barrett Lamb, David Bryan, Justin Legarsky, Kevin A. O'Connor, Kenneth F. McDonald, and Sarah A. Mounter: University of Missouri

A compact, high power microwave array antenna has been developed for use in high power RF systems. The array uses a nanocomposite with high dielectric constant and low loss at microwave frequencies to reduce the array size. The array is composed of 128 dielectric lens antennas with a total cross-sectional area of 3.5 m2 and is fed by a single 20-MW source. Splitters divide the power into 128 legs to provide equal power to each antenna element. Dielectric-loaded antennas and waveguides are used to reduce the size of the array. Independently controlled phase shifters are used for beam steering. The use of nanocomposites in the antenna elements and the feed structure reduces the antenna volume by 80%. The array gain has been simulated to be up to 26.6 dBi and the main beam can be electrically steered at angles up to plus or minus 34 degrees while maintaining gain of approximately 23 dBi. This paper provides an overview of the design, simulation, and measurement of each dielectric lens antenna element, as well as details of the design and simulation of the antenna array.
KEYWORDS: High power microwaves, Lens antenna, Phased array, Dielectric loaded antenna
PAGES 68-89

High-Power-Density Solutions for Directed Energy Weapon System Applications
Hernando Munevar and Emanuel Papandreas, Candent Technologies, Inc.

This paper discusses the trade studies and system performance analysis conducted to settle on a high-efficiency gas turbine generator (GTG) as the solution to provide a 250-kW high-power-density energy source for directed energy weapon (DEW) systems. The paper describes the power source options assessed, and the trade study describes how each of the options compares relative to the others based on pertinent figures of merit. In addition, the paper addresses the general characteristics of the GTG system selected, which is comprised of a high-speed generator, gas turbine engine, recuperator (heat exchanger), and required subsystems. Lastly, the paper discusses the size and portability of the power source system.
PAGES 90-104

Joint Non-Lethal Weapons Program's Non-Lethal Directed Energy Weapons-Past, Present, and Future
David B. Law; Joint Non-Lethal Weapons Directorate Technology Division

The Joint Non-Lethal Weapons Directorate's Science and Technology Strategic Plan for future non-lethal directed energy weapon activity is outlined. The results of the past 20 years of research in non-lethal directed energy weapons as funded by the Directorate are summarized. Some of these efforts have resulted in initial prototypes and in system demonstrators.
PAGES 105-117

Volume 6, Number 1, Journal of Directed Energy

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