Impulse Radiation Research Articles

Ultra‐wideband Vivaldi antenna design for multisensor adaptive ground‐penetrating impulse radar

AbstractThis paper describes a partially dielectric‐loaded Vivaldi antenna (PDVA) structure that maintains ultra‐wideband antenna characteristics over a bandwidth ratio greater than 25:1 so as to improve the impulse radiation characteristics for multisensor adaptive ground‐penetrating Radar (GPR) operations. The PDVA is introduced for metal‐detector‐combined GPR head designs in order to avoid performance degradations based on the sensor interferences. It is shown that high gain, low input reflection, and signal‐ringing levels over the wide operational bands are attainable for a PDVA with proper dielectric and absorber loadings. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 834–839, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21491

Impact of near field dispersion on time domain susceptibility tests

Abstract. This paper considers the effect of changes of the waveform parameters over the distance. The objective is to show the near field effects on transient radiation and how near the equipment under test can be located to an antenna without significant changes of the width or rise time of the field pulse. It is shown that the well known frequency domain estimation models fail because the dimension of antenna systems and the wave propagation lead to a special kind of dispersion. The importance of this near field dispersion for practical applications is demonstrated by both theoretical considerations and measurements with a half impulse radiation antenna.

Radiance of Intense Impulse Soft-X-Ray Plasma Sources

Absolute radiance of impulse radiation from vacuum spark discharges and laser-produced plasmas have been analysed and compared.

Transient interactions between tiny interfacial antennas on half‐space lossless dielectric

The interfacial electric‐field interaction subdivides into four cases: the HH, VV, HV, and VH cases. For each case, we derive the impulse‐response solution of the interfacial electric field generated by an infinitesimal impulse current source at the same interface, using plane‐time Fourier transform and a variant scheme of the Cagniard‐de‐Hoop method. We show that it is possible to obtain exact explicit‐form solutions for the HH and VV cases, whereas we have to evaluate the electric fields only by numerical calculations for the HV and VH cases since the exact solutions are yet unavailable. Various aspects of the impulse‐response solutions, such as the impulse radiation characteristics and the transient responses to time‐Gaussian inputs, are investigated as well as the offset‐differentiated field characteristics for the HV and VH cases. We also discuss the effect of the lower‐medium loss on the transient waveforms and the effect of the interface that makes the interfacial interaction quite different from the interaction in free space.

Ultra-wideband impulse radar-an overview of the principles

Over the past decade, extensive research work has been carried out to develop the ultra-wideband (UWB) technology for radar applications, and to resolve the practical challenges in implementing an efficient UWB radar system. In this paper, we present an overview of the basic principles of UWB impulse radar. The focus is on the principles of UWB signal generation, impulse radiation, waveform design, pulse compression, range-velocity resolution (ambiguity function), array beamforming, and radar-target signature.

Investigation of the radiation characteristics of radiators based on combustion of aerosuspensions of aluminum powders

The results of measurements of radiation and gas-dynamic characteristics in combustion of an aluminum powder initiated by an electric explosion of a foil are given. Radiation energy in different spectral ranges is measured. The formation and movement of a cloud of combustion products is investigated. It is shown that effective sources of impulse radiation in the megajoule range can be developed on the basis of electric explosion in powders.

Noise source identification on an IBM typewriter using sound intensity technique

Noise source identification was carried out on an IBM ball element electric typewriter. The selective operation method was used to survey the vibration and sound pressure of different typewriter sources. The sound power radiation of different noise sources was measured using the two‐microphone sound intensity technique. The measurements showed that the impulse radiation of the ball element striking the platen is the highest noise source, and the difference between the results with and without paper is small. Several indexes that suppose to qualify the accuracy of sound power measurements using the sound intensity technique will be discussed. [Work supported by IBM, Austin, TX.]

A Quantum Theory of the Impulse Radiation

A quantum theory of the impulse radiation.---Evidence is presented which indicates that the quantum ejects the photo-electron by a sideways impulsive action in the direction of the electric force. It is therefore assumed that a similar sideways reaction perpendicular to the direction of emission of the quantum acts on the cathode electron during the creation of the quantum. From this it follows that the frequency of the radiation emitted at an angle $\ensuremath{\varphi}$ with the cathode beam cannot exceed the value ${v}_{0}=\frac{m{\ensuremath{\beta}}^{2}{c}^{2}{sin}^{2}\ensuremath{\varphi}}{[2h\sqrt{1\ensuremath{-}{\ensuremath{\beta}}^{2}}(1\ensuremath{-}\ensuremath{\beta}cos\ensuremath{\varphi})]}$ where $\ensuremath{\beta}c$ is the velocity of the cathode electron; hence the forward radiation exceeds the backward in hardness, in agreement with observation. Assuming the electric force of the quantum is determined by the sideways impulse acting in the creation of the quantum, results for polarization are obtained which agree with those of the wave theory and hence with observation. The problem of intensity distribution of the radiation from a target is a statistical one which will be treated later; but it is shown that the results of Stark and Loebe are in accord with this theory. The quantum is supposed to be a tiny corpuscle which undergoes a sideways cyclic vibration as it proceeds. This theory is seen to include a momentum relation as well as the Einstein photoelectric relation. It agrees in most formal results with Sommerfeld's wave theory.