TECHNOLOGY AREAS: Nuclear OBJECTIVE: The goal of this study is to develop a portable, low-cost, and compact antenna array system. This system will be capable of wide bandwidth operations to support various Electromagnetic Pulse (EMP) and High-Power Microwave (HPM) sources, both current and future. The antenna system can be deployed today with existing EMP sources and will also support future low jitter sources for array combining on larger test assets. A standardized coaxial interface will support multiple sources (EMP and HPM), enabling faster and more efficient testing of critical assets. DESCRIPTION: In the past, the DoD had over 20 EMP simulators across the country for missile and aircraft testing ("EMP Simulators for Missiles and Airplanes," M.K. Bumgardner, et al., February 9, 1974). These simulators had a wide range of capabilities, including both horizontal and vertical polarization, and many used arrays to combine multiple pulsers (10-500 kV) with reconfigurable setups. Depending on the operational scenario of the System Under Test (SUT), test setups varied: vertical missile in launch stage, horizontal flight, aircraft experiencing horizontal or vertical EMP, etc. Today, only a few EMP simulators remain at fixed sites, with limited adjustability and reconfigurability. The art of the EMP simulator array has been lost, and there is a need to recreate a portable and reconfigurable simulator. Efforts within the electromagnetic effects Test and Evaluation (T&E) community are underway to develop low jitter sources specifically for EMP testing. However, a variety of pulsers (EMP, RS-105, HPM) are available today that meet some test requirements. What is lacking is a rugged, portable Transverse Electromagnetic Mode (TEM) array structure capable of delivering the EM field to test assets in a reconfigurable manner. The prototype objective is to deliver a system that can be set up in a day at a test site and be reconfigurable for three antenna configurations: horizontal bounded wave, vertical bounded wave, and overhead radiating, all in TEM mode. The system should be large enough for a 20-meter missile but also scalable to different sizes. It should have sufficient holdoff for 1.5 MV sources and bandwidth for low jitter EMP sources (not more than 300 ps jitter), UltraWide Band (UWB) sources, and HPM sources up to X Band. This requires an electromagnetic model and simulation (M&S) effort to ensure the launch section has sufficient bandwidth for fast risetimes and higher frequency content. This approach is similar to existing Gigahertz TEM (GTEM) cells, which are driven by a wide range of sources. However, this system is designed for open test volumes and outdoor use. The focus of this effort is on the antenna arrays, launch area, interconnections, terminations, spatial combining, impedance matching, lifting structure, and ruggedness of a portable system, not on the pulser itself. An example of a pulser that would be used is the Applied Physical Electronics LC (APELC) 1 MV RS-105 pulser (IRAD), a 10 kV FID pulser. This and other wideband sources may be used for demonstration. AFNWC will coordinate with the vendor during concept development to determine which DoD assets (pulsers) will be used. Corresponding impedance matching circuits and adapters will be designed and built. RS-105 simulators exist up to the 1 MV range, high voltage coaxial cables exist in the >1 MV range for short pulses, and low jitter pulsers have been demonstrated in the 100s kV range. Placing the launch section on the bounded wave structure and connecting to ground sources via coaxial cable allows connection to existing sources not designed to be lifted. Some allowance for weight will be included for future pulsers to be mounted with the launch section. For example, a 1 MV pulser on the proposed array produces a 50 kV/m field across a 20m SUT. PHASE I: This topic is part of the D2P2 program, so no Phase I awards will be made. However, "Phase 1-type" feasibility documentation should be provided to demonstrate proof of concept for an individual planar antenna. APELC has built over 10 RS-105 simulators of various voltages and sizes, and the array approach has been in use as recently as the 1990s. PHASE II: The objective is to design and develop a planar array antenna capable of illuminating a 20-meter SUT, driven by either Government Furnished Equipment (GFE) or the vendor's pulser. This builds on existing RS-105 simulators but aims to advance the design with improved ruggedness for transportability and a wider bandwidth. An M&S deliverable will model a larger system's electromagnetic performance for larger SUTs, such as full-size aircraft, using various technical approaches with sources ranging from 100kV to 1.5 MV. PHASE III DUAL USE APPLICATIONS: For Phase III the initial application is anticipated to be an arrayed pulse power phaser, with a horizontal or vertical polarization that can be used for EMP E1 subsystem or system level testing which can be transported based on program needs for AFNWC. The contractor will have to work with DoD and civilian agencies to customize the test capability for various mission critical system and infrastructure applications. Other applications of the PCSS triggering systems are expected to include future large-scale pulsed power systems requiring many thousands of high reliability spark gap triggering systems. The contractor will have to work with both the Air Force Nuclear Weapons Center (AFNWC) and the Defense Threat Reduction Agency (DTRA) for detailed Test & Evaluation (T&E) requirements. REFERENCES: 1. Sierra, Gustavo, Transportable Electromagnetic Pulse System. 2. Nickolas, Seth, Photoconductive Semiconductor Switch Driven Antenna and Array Design. KEYWORDS: compact; emp; hpm; pulsar; antenna array; transverse electromagnetic mode
