This paper explains the design and production of two autonomous ultrawideband (UWB) radiation sources. These sources consist of a high-gain broadband antenna that is driven by one of two subnanosecond pulsed power sources. Each source is made up of a Marx generator and a pulse-forming device based on the use of a gaseous spark gap. The first source combines a four-stage 200-kV/34-J Marx generator with a coaxial pulse-forming line. Its main characteristics are an output voltage of 100 kV, a 250-ps rise time, a subnanosecond pulse duration, and a repetition rate of about 40 Hz. The second pulsed source is a ten-stage subnanosecond Marx generator that delivers pulses in the 250-kV/1.5-J range, with a 300-ps rise time and a subnanosecond pulse duration at a pulse repetition rate of 350 Hz. Probes were produced based on capacitive line dividers to measure both the temporal characteristics and the high-voltage (HV) amplitude of the pulses delivered by the pulsed power sources. The antenna, combined with these two pulsed sources, is a traveling-wave antenna called the Valentine antenna. Some mechanical modifications were made to the antenna to improve its dielectric strength. First, a 3-D model of the antenna was created on time-domain electromagnetic software to study the influence of these modifications on its main radiating characteristics. Its high gain and its capability to radiate short pulses without dispersion allow us to achieve a high measured figure of merit (the maximum value of far-field peak-to-peak electric field strength multiplied by the distance). A new method called the Instantaneous Electromagnetic Field Measurement by Signature of a Neutral Object (MICHELSON) method is used to measure the very intense electromagnetic fields that are radiated. The incident field is diffracted by a special small-dimension target. The diffracted field is measured by a conventional low-power UWB antenna. The target that is used has small dimensions, and no cables are used in the field region; thus, the electromagnetic interference that is generated and undergone by the measurement device is considerably limited. The figure of merit that is measured is 436 kV.

High Pulsed Power Sources for Broadband Radiation

This paper presents the guidelines for the development and optimization of wireless sensors based on the modulated scattering technique (MST). In particular, this paper is focused on the design and optimization of different MST tag prototypes with different modulation techniques. In addition, it is shown how to obtain the best performance of such sensors in terms of communication range and load efficiency. The preliminary measurements obtained with different experimental tag prototypes demonstrate that these MST sensors are able to measure and to correctly send data without an expensive radio frequency (RF) transmitter or a bulky wired connection. The results obtained show that such sensors could be an interesting alternative to standard RF identifier and wireless sensors.

Guidelines for the Design and Optimization of Wireless Sensors Based on the Modulated Scattering Technique

11 UWB antennas in the field of high pulsed power For the last few years, the generation of high-power electromagnetic waves has been one of the major applications of high pulsed power (HPP) It has aroused great interest in the scientific community since it is at the origin of several technological advances Several kinds of high power radiation sources have been created There currently appears to be a strong inclination towards compact and autonomous sources of high power microwaves (HPM) (Cadilhon et al, 2010; Pecastaing et al, 2009) The systems discussed here always consist of an electrical high pulsed power generator combined with an antenna The HPP generator consists of a primary energy source, a power-amplification system and a pulse forming stage It sends the energy to a suitable antenna When this radiating element has good electromagnetic characteristics over a wide band of frequency and high dielectric strength, it is possible to generate high power electromagnetic waves in the form of pulses The frequency band of the wave that is radiated can cover a very broad spectrum of over one decade in frequency In this case, the technique is of undoubted interest for a wide variety of civil and military applications Such applications can include, for example, ultra-wideband (UWB) pulse radars to detect buried mines or to rescue buried people, the production of nuclear electromagnetic pulse (NEMP) simulators for electromagnetic compatibility and vulnerability tests on electronic and IT equipment, and UWB communications systems and electromagnetic jamming, the principle of which consists of focusing high-power electromagnetic waves on an identified target to compromise the target’s mission by disrupting or destroying its electronic components Over the years, the evolution of the R&D program for the development of HPM sources has evidenced the technological difficulties intrinsic to each elementary unit and to each of the physical parameters considered Depending on the wave form chosen, there is in fact a very wide range of possibilities for the generation of microwave power The only real question is

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Ultra Wideband Antennas for High Pulsed Power Applications

D-dot sensors were designed and tested for the measurement of nanosecond high-voltage pulses. Computer simulation results showed that the I-type sensor has an acceptable response in a wide range of frequency among three types of sensors such as I, ∇, and T. The I-type sensor has coaxial cylinder shape, which consists of a brass inner conductor, a Teflon middle dielectric, and an aluminum outer conductor. Since I-type showed good linearity up to 1.2 GHz, we calibrated the sensor using relatively low frequencies. The attenuation ratio of the integrated signal of the D-dot sensor was calibrated against a standard high-voltage probe (Tektronix P6015, 75-MHz bandwidth). The measured attenuation ratio and standard deviation were 7.70×1012 and 0.0608×1012, respectively. The measured attenuation ratio was in good agreement with the calculated ratio within 7.5%. The operational characteristics of the sensor were tested by measuring nanosecond voltage pulses generated from a Blumlein pulse forming line. We measured high-voltage pulses having 300 kV, 5-ns pulsewidth, and 300-ps rise time using the designed D-dot sensor. The accuracy of the sensor enabled detection of several tens of picosecond differences in the rise time of the high-voltage pulses resulting from different gap distances in the peaking switch.

Design and Test of an Electric Field Sensor for the Measurement of High-Voltage Nanosecond Pulses

Nowadays, a broad range of modern defense applications requires compact pulsed power generators to produce high-power electromagnetic waves. In a conventional design, such generators consist of a primary energy source and an antenna, separated by a power-amplification system, such as a Marx generator or a Tesla transformer, which forwards the energy from the source to the antenna. The present system, however, uses a novel and very compact high-voltage resonant pulsed transformer to drive a dipole antenna. The complete pulsed power source, termed MOUNA (French acronym for “Module Oscillant Utilisant une Nouvelle Architecture”), is composed of a set of batteries, a dc/dc converter for charging four capacitors, four synchronized spark gap switches, a resonant pulsed transformer that can generate 555 kV/265 ns pulses, an oil peaking switch and, during preliminary testing, a dipole antenna. The paper not only provides design details for each system component, but also presents the mechanical arrangement of the complete pulsed power system and the electrical diagnostics, particularly those related to measurement of the resonant transformer output waveform, the line oscillations, and the radiated electric field.

MOUNA: An Autonomous, Compact, High-Power, and Wideband Electromagnetic Source Based on a Novel Resonant Pulsed Transformer

This paper aims at presenting the design and realisation of an autonomous, ultra wideband (UWB) radiation source consisting of a high gain broadband antenna driven by a subnanosecond pulsed power source.

A 250KV-300PS-350HZ Marx generator as source for an UWB radiation system

The intention of this paper is to present the instantaneous electromagnetic field measurement by signature of a neutral object (MICHELSON) method. The MICHELSON method is relatively new and enables the measurement of high-level electromagnetic fields from the utilization of a target. The incident field scattering on the target allows us to move the field measurement to a new location where the scattered field can then be measured using simple equipment and without breakdown risk. This method does away with the necessity for cables in the test zone. When using small targets, the induced disturbances in the incident field are limited. The MICHELSON method is implemented to characterize high-level electromagnetic sources whereby the signals radiated can be harmonic signals as well as transient pulses.

B. Cadilhon

Papers

A 250KV-300PS-350HZ Marx generator as source for an UWB radiation system

Utilization of Target Scattering to Measure High-Level Electromagnetic Fields: The MICHELSON Method