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Wideband and ultrawideband (UWB) technologies have achieved notable progress in recent years, aided immeasurably by improvements in solid-state manufacturing, computers, and digitizers. As a result, wideband systems that were difficult or impossible to implement ten years ago are now being built for an increasingly wide variety of applications including transient radar, concealed object detection, mine clearing, pipeline inspections, archeology, geology, electronic effects testing, and communications. In this paper, we discuss current wideband source technology around the world as well as laboratory and test facilities. We also will briefly touch on frequency limitations of anechoic chambers, design of transmission line simulators, frequency regulation requirements for outdoor ranges, and personnel exposure limits. Index Terms--High-power microwaves, sources, test ranges, transient, ultrawideband.

Personnel at the Air Force Weapons Laboratory introduced many innovative concepts in electromagnetics (EM) and created new antenna and sensor designs that made possible much of the wideband electromagnetics technology we have today. Many practitioners in high power EM are familiar with wideband sensors and simulators, but may not be aware of their origin. The purpose of this paper is to describe some of the concepts from which many of the designs evolved and provide some interesting insight into the mind of Dr. Carl Baum, who created them. [ABSTRACT FROM AUTHOR]

This paper describes developments in high-altitude electromagnetic pulse (HEMP) test methods. More specifically, we describe the most commonly used HEMP test methods and associated measurement systems used to assess systems and equipment to the early-time (E1) effects of HEMP. Short case studies of the application of these test methods are included. Finally, computational electromagnetics (CEM) is a subject that has advanced significantly in recent years. This paper summarizes developments in this area and the supporting role that CEM has when undertaking assessments of the impact of HEMP on systems. [ABSTRACT FROM AUTHOR]

The five decades since the discovery that the electromagnetic pulse created by a nuclear detonation at high altitude (HEMP) threatens the survivability of strategic military and civilian electronic systems saw development and construction worldwide of many large test facilities for simulating that threat. This paper describes simulators in three categories: guided wave, dipole, and hybrid. In 2002, the International Electrotechnical Commission (IEC) published a compendium of technical information about 42 simulators in 14 countries using this classification system. This paper provides a summary of information in the compendium and describes some developments in the field since 2002. [ABSTRACT FROM AUTHOR]

When designing and qualifying hardened systems to an electromagnetic pulse (EMP) or electromagnetic interference standard, one needs a practical way to measure the effectiveness of the shield. It is not possible to test every system in a threat-level EMP test facility, so alternative methods have been developed. This paper reviews the advances made in low-level continuous wave measurement technology since the last EMC Special Issue published in 1978. These include system-level illumination as well as localized test methods for individual hardening elements. Available illuminating antennas for use on aircraft, ships, and ground-based communications systems are reviewed. [ABSTRACT FROM AUTHOR]

There are many different definitions of the risetime of a transient waveform. In the context of high-altitude electromagnetic pulse (HEMP) standards, the 10–90% risetime of an idealized double exponential waveform has been defined and used for many decades. However, such a risetime definition is not strictly applicable to the transient voltage out of a pulse generator, since no practical switch can close in zero time. In this paper, we discuss various definitions and their applicability. More importantly, pulse power technology has evolved over five decades and the achievable risetimes have come down from 10s of nanoseconds to 10s of picoseconds. As a corollary, the highest achievable voltage gradient has been going upwards of 10^15 V/s. In this paper, we review the definitions of risetime, and trace the evolution of technology and HEMP Standards, exclusively for the E1 environments. [ABSTRACT FROM AUTHOR]

We present system considerations for the design of a tunable mesoband source based on a parallel-plate Blumlein architecture. Here, we discuss the switching characteristics, electrode shaping, and tunability of a system designed to operate from 100 MHz to 1.5 GHz with charge voltages up to 100 kV. The first prototypes that have been tested and are reported on here have been tested at charge voltages up to 50 kV for operating frequencies of 500 MHz and 1.4 GHz. The requirements of the high-voltage system necessitated a high-pressure switch that is fully integrated into the Blumlein, requiring detailed mechanical design. A full system design is presented, which will be constructed and tested in future work. [ABSTRACT FROM AUTHOR]

Quarter-wave switched oscillators (SWOs) are an important technology for the generation of high-power mesoband waveforms. The operation of these SWOs has been discussed for the past several years, but a detailed discussion of the design of these sources for particular waveforms has been lacking. In this paper, we relate several important parameters such as gap spacing, oscillator shape, and antenna to the properties of the radiated waveform. [ABSTRACT FROM AUTHOR]

This paper investigates the possibility of using the impulse-radiating antenna (IRA) as both a transmitter and receiver of electromagnetic energy for the purpose of target identification. Of specific interest is estimating the induced open-circuit voltage at the IRA's source terminals, when it is illuminated by the scattered EM field from simple conducting bodies excited by an incident field from the same IRA acting as a transmitter. In this study, several different canonical scatters are considered, including thin wires, spheres, conducting boxes, and an infinite conducting plate. For a 7 kV pulse excitation of the IRA, received peak transient voltages at the antenna ranged from a few volts to about 400 volts, depending on the scatterer. [ABSTRACT FROM AUTHOR]

Ultrawideband (UWB) systems that radiate very high-level transient waveforms and exhibit operating bandwidths of over two decades are now in demand for a number of applications. Such systems are known to radiate impulse-like waveforms with rise times around 100 ps and peak electric field values of tens of kilovolts per meter. Such waveforms, if properly radiated, will exhibit an operating spectrum of over two decades, making them ideal for applications such as concealed object detection, countermine, transient radar, and communications. In this paper, we describe a large, high-voltage transient system built at the Air Force Research Laboratory, Kirtland AFB, NM, from 1997 to 1999. The pulsed power system centers around a very compact resonant transformer capable of generating over 1 MV at a pulse-repetition frequency of ∼ 600 Hz. This is switched, via an integrated transfer capacitor and an oil peaking switch onto an 85-Ω half-impulse radiating antenna. This unique system will deliver a far radiated field with a full-width at half-maximum on the order of 100ps, and a feld-range product (r Efar) of ∼ 5.3 MV, exceeding all previously reported results by a factor of several. [ABSTRACT FROM AUTHOR]

Presents a study which reviewed the progress and areas of research into the development of ultra-wideband (UWB) technology. Background information on UWB research programs; Application of UWB microwave sources and antennas; Conclusion.

Reviews the progress in fast, high voltage switching and ultra-wideband (UWB) transmitter development. Importance of switching elements; Discussion on solid-state UWB sources and UWB antennas; Conclusions.