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Jun 1999

Volume 70, Issue 6, pp. 2567-2883

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back to top ELECTRONICS; ELECTROMAGNETIC TECHNOLOGY; MICROWAVES

Application of band-stop filters for the 30–200 GHz range in oversized microwave systems

H. J. van der Meiden

Rev. Sci. Instrum. 70, 2861 (1999); http://dx.doi.org/10.1063/1.1149808 (3 pages) | Cited 2 times

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A simple and cheap method has been developed to prepare band-stop filters for the frequency region 30–200 GHz with a typical attenuation in the stop band of more than 27 dB. This filter consists of periodic metallic structures deposited on a thin substrate. The preparation is achieved by applying a commonly used chemical etching technique on a commercially available thin print board. These so called “capacitive meshes” are applied successfully at the Rijnhuizen Tokamak Project for protection of a microwave diagnostic against high power microwave input. © 1999 American Institute of Physics.
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52.70.Gw Radio-frequency and microwave measurements
84.40.Az Waveguides, transmission lines, striplines
07.57.Kp Bolometers; infrared, submillimeter wave, microwave, and radiowave receivers and detectors
52.55.Fa Tokamaks, spherical tokamaks

Electrically controlled broadband microwave attenuator with p-i-n diode switches

Hiroshi Nakano and Yoshihiko Kato

Rev. Sci. Instrum. 70, 2864 (1999); http://dx.doi.org/10.1063/1.1149809 (2 pages)

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An electrically controlled broadband attenuator composed of two p-i-n diode switches and two quadrature hybrid couplers has been newly developed. Its attenuation can be precisely controlled by electrical pulses and also easily measured by counting its pulse repetitions. It can thus be used for broadband microwave measurements, especially noise measurement. When controlled with pulses whose width was 10 μs and repetition frequencies were between 10 and 90 kHz, this attenuator’s attenuation to repetition frequencies was linear for signal frequencies in the range of 2–12 GHz. © 1999 American Institute of Physics.
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84.37.+q Measurements in electric variables (including voltage, current, resistance, capacitance, inductance, impedance, and admittance, etc.)
07.57.-c Infrared, submillimeter wave, microwave and radiowave instruments and equipment
85.30.Kk Junction diodes
84.40.-x Radiowave and microwave (including millimeter wave) technology
84.32.Dd Connectors, relays, and switches

Design and evaluation of a low thermal electromotive force guarded scanner for resistance measurements

Dean G. Jarrett, James A. Marshall, Thomas A. Marshall, and Ronald F. Dziuba

Rev. Sci. Instrum. 70, 2866 (1999); http://dx.doi.org/10.1063/1.1149810 (6 pages)

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The design and testing of a low thermal electromotive force guarded scanner, developed to provide completely guarded switching when used with actively guarded resistance bridge networks, is described. The design provides a continuous guard circuit trace on the scanner circuit boards that surrounds the relay contacts and protects the measurement circuit from leakages to ground. Modification to the circuit boards and relays of the guarded scanner are explained. Several tests were developed to evaluate the guarding effectiveness, including isolating sections of the guard circuit to create a potential drop between the main and guard circuits. Calibration of standard resistors using the guarded scanner has shown relative differences less than 1×10−6, 30×10−6, and 150×10−6 for measurements made with and without the guarded scanner at nominal resistances of 1, 10, and 100 GΩ, respectively. The substitution method was used to significantly reduce the relative differences between channels to less than 0.5×10−6, 3×10−6, and 30×10−6 for nominal resistances of 1, 10, and 100 GΩ, respectively. Applications for the guarded scanner in automated direct current measurement systems are presented. © 1999 American Institute of Physics.    
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84.37.+q Measurements in electric variables (including voltage, current, resistance, capacitance, inductance, impedance, and admittance, etc.)
06.20.F- Units and standards
84.32.Ff Conductors, resistors (including thermistors, varistors, and photoresistors)
07.50.Hp Electrical noise and shielding equipment

Improved calibrator for the evaluation of batch produced strain gauges in cryogenic environments

W. H. Huber, L. M. Hernandez, and A. M. Goldman

Rev. Sci. Instrum. 70, 2872 (1999); http://dx.doi.org/10.1063/1.1149811 (3 pages) | Cited 3 times

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We have constructed a simple, improved apparatus for calibrating strain gauges down to liquid helium temperatures to permit an estimate of the repeatability and linearity of commercially available, batch produced, metal foil strain gauges. The apparatus is based upon an original design first proposed by McClintock [R. M. McClintock, Rev. Sci. Instrum. 30, 715 (1959)]. Calibrations performed on a particular batch produced metal foil strain gauge indicate that it behaved ideally at low temperatures. Although the gauge resistance was strongly temperature dependent, the gauge factor was virtually independent of temperature and did not display any detectable nonlinearity or hysteresis. © 1999 American Institute of Physics.
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07.10.Pz Instruments for strain, force, and torque
07.07.Mp Transducers
07.20.Mc Cryogenics; refrigerators, low-temperature detectors, and other low-temperature equipment
06.20.F- Units and standards
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