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Displaying 776 - 800 of 1560

Calibration of Nonreciprocal Radar Systems

November 14, 2002
Author(s)
Lorant A. Muth
The calibration of nonreciprocal radars has been studied extensively. Here we present a robust calibration procedure using Fourier analysis of back-scatter data from a rotating dihedral. We derive a set of nonlinear equations in terms of the Fourier

Analysis of Phase-Dependent RCS Measurements

November 8, 2002
Author(s)
Lorant A. Muth, Timothy Conn
Free space coherent radar cross section measurements on a moving target will trace a circle centered on the origin of the complex (I,Q) plane. Noise will introduce only small random variations in the radius of the circle. In real measurement configurations

Methods to Estimate and Reduce Leakage Bias Errors in Planar Near-Field Measurements

November 8, 2002
Author(s)
Allen C. Newell, Jeffrey R. Guerrieri, Katherine MacReynolds
This paper describes two methods that can be used to measure the leakage signals, predict the effect on the far-field pattern and correct the measured data for leakage bias errors without additional near-field measurements. One method is an extension and

Spherical Near-Field Antenna Measurements Using Nonideal Measurement Locations

November 8, 2002
Author(s)
Ronald C. Wittmann, Bradley Alpert, Michael H. Francis
We introduce a near-field spherical scanning algorithm that relaxes the usual condition requiring data points to be on a regular spherical grid. Computational complexity is of the same order as for the standard (ideal-positioning) spherical-scanning

Spherical Scanning Measurements Using Truncated Data Sets

November 8, 2002
Author(s)
Ronald C. Wittmann, Carl F. Stubenrauch, Michael H. Francis
We discuss the mitigation of truncation errors in spherical scanning measurement. The main emphasis is the spherical harmonic representation of probe transmitting and receiving functions; however, our method is applicable to near-field measurement of

Ultra-Wideband Antenna Pattern Characterization in a Non-Ideal EM Facility

November 8, 2002
Author(s)
Jason Veneman, David R. Novotny, Chriss A. Grosvenor, Robert T. Johnk, Seturnino Canales
We present and analyze a procedure for performing relative, ultra-wideband antenna pattern measurements in a non-ideal EM facility. Ultra-wideband, short-impulse, TEM horn transmission measurements were performed and compared with computer-modeled

Ultra-Wideband TEM-Horn Antenna Design using Numerical Methods

November 8, 2002
Author(s)
Chriss A. Grosvenor, David R. Novotny, Jason Veneman, Seturnino Canales
TEM, time-domain antennas are designed to reproduce accurately the time characteristics of an impulsive, incoming field. The response to the fields must be constant in amplitude and linear in phase for minimal distortion. Numerical techniques are employed

Monte Carlo Simulation of Noise Parameter Uncertainties

November 1, 2002
Author(s)
James P. Randa, Wojciech Wiatr
We present results for uncertainties in noise-parameter measurements, obtained using a Monte Carlo simulation of the measurements. Sets of data were generated to simulate measurements on a low-noise amplifier, with given uncertainties in the underlying

Noise-Parameter Uncertainties: A Monte Carlo Simulation

October 1, 2002
Author(s)
James P. Randa
This paper reports the formulation and results of a Monte Carlo study of uncertainties in noise-parameter measurements. The simulator permits the computation of the dependence of the uncertainty in the noise parameters on uncertainties in the underlying

Pulsed inductive microwave magnetometer

October 1, 2002
Author(s)
Anthony B. Kos, Thomas J. Silva, Pavel Kabos
We describe the apparatus, software, and measurement procedures for a pulsed inductive microwave magnetometer (PIMM). PIMM can measure the dynamical properties of materials used in recording heads for magnetic storage applications and it can be used as a

Rabi Oscillations in a Large Josephson Junction Qubit

September 9, 2002
Author(s)
John M. Martinis, Sae Woo Nam, Joe Aumentado, C Urbina
We have designed and operated a circuit based on a large-area current-biased Josephson junction whose two lower energy quantum levels could be used to implement a solid-state qubit. The circuit allows measurement of the qubit states with a fidelity of 85%

NbN Film Development for PHEB Devices

September 1, 2002
Author(s)
Eyal Gerecht, V. A. Bhupathiraju, Erich N. Grossman, Jeffrey W. Nicholson, Fernando Rodriguez-Morales, Dazhen Gu, Sigfrid Yngvesson
We have developed a process for fabricating a thin NbN film at the National Institute of Standards and Technology in Boulder, CO. A two-fold approach can be taken. The first is to maximize the critical temperature of the superconducting device (growing

Noise Temperature for Nb DHEB Mixer Receiver for Far-Infrared Spectroscopy

September 1, 2002
Author(s)
Eyal Gerecht, Carl D. Reintsema, Erich N. Grossman, A. L. Betz, R. T. Boreiko
We are reporting a noise temperature measured on a diffusion-cooled hot electron bolometeric (DHEB) mixer designed for a heterodyne focal plane array to study lines with frequencies of 2 THz and above. Our fabrication process utilizes selective ion milling

Shielding Effectiveness Measurements Using the Direct Illumination Technique

August 20, 2002
Author(s)
Chriss A. Grosvenor, David R. Novotny, Robert T. Johnk, Seturnino Canales, Jason Veneman
In this paper we discuss the direct illumination and reverberation chamber techniques for measuring shielding effectiveness. using the reverberation chamber as our reference, we explain the differences between the measurements and corrections applied to

Pseudo-Isotropic Source for Anechoic Chamber Qualification

August 19, 2002
Author(s)
Perry F. Wilson, John M. Ladbury, Galen H. Koepke
A pseudo-isotropic source is presented. The source consists of an electrically-large cavity with internal excitation (horn antenna), a variable internal boundary condition (a rotating paddle as in a reverberation chamber), and randomly placed apertures for

New Techniques for Calibrating Across-the-Road Traffic Radars

August 17, 2002
Author(s)
Claude Weil, Dennis G. Camell, David R. Novotny, Robert T. Johnk, Arthur Ondrejka
We discuss simulator units for calibrating across-the-road Doppler traffic radars used in highway speed enforcement. Two units of essentially the same design were developed, one operating at K-Band (24 GHz) and the other at Ka-Band (35 GHz). The signal

Phantom Materials for Metal Detector Research

August 17, 2002
Author(s)
James R. Baker-Jarvis, Raian K. Kaiser, Michael D. Janezic
The purpose of this paper is to discuss the characterization of materials that mimic the electromagnetic characteristics of the human body from low frequencies to 10 MHz and over a temperature range of 15 C. to 40 C. The materials studied were: 1) a
Displaying 776 - 800 of 1560