Gain Measured Research Articles

On the One-Antenna Gain Measurement Method in Probe Station Environment at mm-Wave Frequencies

In this paper, an antenna gain measurement method for millimeter-wave antennas in an on-wafer probe station environment is studied. The one-antenna gain measurement has been known since the 1940s. However, the authors believe that this extension of their previous work is the first time when the method is systematically studied in the on-wafer probe station environment. The main difference between the original one-antenna gain measurement and our method is that in the probe station environment, the space is limited and, therefore, the reflecting plate dimensions are limited. We have studied the effect of the reflector size limitation through computations using physical optics and through measurements with a standard gain horn (SGH) and with a printed microstrip patch antenna. The necessary size of the reflecting plate naturally depends on the beamwidth of the antenna under test and on the distance. Time gating has been applied in the retrieving calculation to filter out multiple reflections. According to this paper, the one-antenna gain measurement in the $W$ -band results in the correct antenna gain with very high accuracy for the highly directional SGH. For the patch antenna, the gain measured in the on-wafer probe station environment agrees well with the simulated one.

Accuracy in measurement of elevation gain in road cycling

Purpose. Accurate measures of elevation gain are important for monitoring energy expenditure and physical load. The aim of this study was to determine the accuracy of barometric devices used for measuring elevation gain. Methods. Observational validation study. Twenty-eight barometric altimeter devices (SRM and Garmin) were used to measure total elevation gain during cycling over three different climbs (length range: 3.2-18.4 km), giving a total of 216 climbs. Â An online mapping tool (http://www.freemaptools.com/elevation-finder.htm) was used to calculate the criterion measure of total elevation gain. Data were categorised into two weather conditions: dry and wet. Results. The standard errors of the estimate for total elevation gain measured by SRM and Garmin devices were 1.5% and 1.9%, respectively. In dry conditions, SRM devices underestimated the total elevation gain by an on average by of ~5% while the Garmin devices underestimated it by ~2%. In wet weather conditions the bias worsened to -25%. Conclusions. Measurements of total elevation gain recorded with devices of differed brands were similarly accurate in dry weather conditions. Wet weather conditions significantly decreased the accuracy of total elevation gain measurements. Â

Intrinsic gain and gain degradation modulated by excitation pulse width in a semiconducting conjugated polymer

We have previously reported that substantially higher optical gain values can be achieved in the conjugated polymer poly[2-methoxy-5-(2′-ethylhexyloxy)-p-phenylene vinylene] (MEH-PPV) through use of transient excitation conditions. In the present paper, we report on a systematic investigation of this behavior to elucidate the physical mechanisms involved, which enables us to distinguish between the fundamental intrinsic gain and an excitation induced degraded gain. Using pump laser pulses having temporal widths longer and shorter than the photoluminescence (PL) decay time of MEH-PPV, both quasi-steady-state (QSS) and transient excitation regimes are explored in our encapsulated waveguide heterostructures [Si(100)/SiO2/MEH-PPV/poly(methyl methacrylate)]. Under transient excitation (25ps pump pulses), extremely large optical gain is observed, reaching a value of 700cm−1 at a maximum pump energy density of 85µJ/cm2. However, under QSS conditions (8ns pulses), considerably lower gain coefficients are achieved with a maximum of ∼130cm−1 at an energy density of 2,000µJ/cm2; this factor of 5 decrease in optical gain performance is observed at the same excitation density as that for transient excitation using ps pulses. We have also employed unencapsulated waveguide structures [Si(100)/SiO2/MEH-PPV/air], which allows us to achieve additional insight on gain degradation under QSS conditions. It is clear that the gain measured under transient conditions is more representative of the intrinsic gain whereas that determined in the QSS regime is degraded by defect-mediated dissociation of emissive states due to localized thermal and oxidative damage to the films. It is in the QSS regime in which most optical gain measurements to date have been performed. These results suggest that further optimization of MEH-PPV – and most likely other conjugated polymers – as a robust optical gain medium can be achieved by consideration of the excitation pulse width.

Radon measurements with charcoal canisters temperature and humidity considerations

Radon testing by using open-faced charcoal canisters is a cheap and fast screening method. Many laboratories perform the sampling and measurements according to the United States Environmental Protection Agency method - EPA 520. According to this method, no corrections for temperature are applied and corrections for humidity are based on canister mass gain. The EPA method is practiced in the Vinca Institute of Nuclear Sciences with recycled canisters. In the course of measurements, it was established that the mass gain of the recycled canisters differs from mass gain measured by Environmental Protection Agency in an active atmosphere. In order to quantify and correct these discrepancies, in the laboratory, canisters were exposed for periods of 3 and 4 days between February 2015 and December 2015. Temperature and humidity were monitored continuously and mass gain measured. No significant correlation between mass gain and temperature was found. Based on Environmental Protection Agency calibration data, functional dependence of mass gain on humidity was determined, yielding Environmental Protection Agency mass gain curves. The results of mass gain measurements of recycled canisters were plotted against these curves and a discrepancy confirmed. After correcting the independent variable in the curve equation and calculating the corrected mass gain for recycled canisters, the agreement between measured mass gain and Environmental Protection Agency mass gain curves was attained.

A study of the relationship between the video head impulse test and air calorics.

The video head impulse test (vHIT) has been proposed as an objective approach to detect peripheral vestibular disorder in a clinical setting. Data from several studies indicate that the vHIT is a useful addition to the vestibular test battery and can give complementary information to caloric testing. This study explores the relationship between lateral canal vestibular occular reflex gain measured using the vHIT system and canal paresis indicated using air calorics in a sample of patients attending a clinic for balance disorder. Sensitivity and specificity of the vHIT test relative to calorics was studied for a clinical sample of 51 patients (20 male, 31 female) who attended a private clinic for balance disorders. vHIT gains were compared to the manufacturer's normative range and to data from a normative study using 30 young volunteers. Of 14 patients in the clinical sample that had significant canal paresis indicated by air calorics, only 4 showed a significant abnormality in either canal using a measurement of vHIT gain. vHIT gain does not correlate with canal paresis as indicated by air caloric testing. vHIT gain appears relatively insensitive to peripheral vestibular disorder as indicated by air caloric testing, although patients that had no caloric response on one side showed abnormal vHIT gain. vHIT testing may be a useful addition to the existing vestibular test battery, but it does not appear to be an alternative to it.

Gain and output power measurements in an electrically excited oxygen–iodine laser with a scaled discharge

Singlet delta oxygen (SDO) yield, small signal gain, and output power have been measured in a scaled electric discharge excited oxygen–iodine laser. Two different types of discharges have been used for SDO generation in O2–He–NO flows at pressures up to 90 Torr, crossed nanosecond pulser/dc sustainer discharge and capacitively coupled transverse RF discharge. The total flow rate through the laser cavity with a 10 cm gain path is approximately 0.5 mole s−1, with steady-state run time at a near-design Mach number of M = 2.9 of up to 5 s. The results demonstrate that SDO yields and flow temperatures obtained using the pulser-sustainer and the RF discharges are close. Gain and static temperature in the supersonic cavity remain nearly constant, γ = 0.10–0.12% cm−1 and T = 125–140 K, over the axial distance of approximately 10 cm. The highest gain measured is 0.122% cm−1 at T = 140 K. Positive gain measured in the supersonic inviscid core extends over approximately one half to one third of the cavity height, with absorption measured in the boundary layers near top and bottom walls of the cavity. Laser power has been measured using (i) two 99.9% mirrors on both sides of the resonator, 2.5 W, and (ii) 99.9% mirror on one side and 99% mirror on the other side, 3.1 W. Gain downstream of the resonator is moderately reduced during lasing (by up to 20–30%) and remains nearly independent of the axial distance, by up to 10 cm. This suggests that only a small fraction of power available for lasing is coupled out, and that additional power may be coupled in a second resonator. Preliminary laser power measurements using two transverse resonators operating at the same time (both using 99.9–99% mirror combinations) demonstrated lasing at both axial locations, with the total power of 3.8 W.

Comparison between difference-frequency generation and parametric fluorescence in quasi-phase-matched lithium niobate stripe waveguides

Tuning curves and gain are two relevant parameters for integrated optical parametric oscillators. We show in this paper that they can be determined with a good precision without building a high-finesse cavity by measurement of the optical parametric fluorescence and difference-frequency generation. In the first part of this paper, we compare theoretically the guided optical parametric fluorescence and the guided difference-frequency generation in the quasi-phase matching configuration. In the second part, we compare experimental results on optical parametric fluorescence in the 1.2-2.2-/spl mu/m region and optical difference-frequency generation from a 1.55-/spl mu/m laser diode using a pump wavelength between 775-795 nm in quasi-phase-matched lithium niobate stripe waveguides. This comparison shows that the gain measured by both methods is identical, but, while parametric fluorescence allows us to obtain the quasi-phase-matching curve, the difference-frequency generation gives a simpler and more accurate measurement of the gain. The combination of these two techniques provides therefore a powerful tool for evaluating the different fabrication processes of the nonlinear waveguides, without actually fabricating a parametric oscillator.

Corroborating cutoff frequency measurements with DC gain measurements

A test for the correct measurement of the cutoff frequency of bipolar transistors is described. The method tests the equality of the low frequency, small signal, current gain measured by a network analyzer, and by DC current measurements. The method is described, and sample data are shown to demonstrate its practical application.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Gain measurements at 1822 nm in C vi generated by a Nd:glass laser

We present recent gain measurements in C VI at 18.22 nm for a soft-x-ray amplifier produced by a line-focused glass laser (1.053 microm) on a solid carbon target. The maximum gain measured was 8 +/- 2 cm(-1) in the recombining plasma column, with additional radiation cooling, with additional radiation cooling by iron impurities.

Free electron laser small signal gain measurement at 10.6 µm

Small signal gain has been observed for 10.6 μm radiation using a constant (untapered) wiggler. The permanent magnet wiggler was 2.65 m long, had a period of 3.56 cm (75 periods) and a magnetic field on axis of 2.67 kG. The gain measured was 1.5 ± 0.4 percent agreeing well with the predicted gain corresponding to the experimental electron beam conditions ( <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">E = 25</tex> MeV, <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">\DeltaE/E = 0.75</tex> percent, <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">\epsilon = 8\pi</tex> mm . mrad, and <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">I = 10</tex> A).

Effect of diffraction on the measurement of gain in optically pumped materials

Maxwell's equations are solved for the propagation of light in an inhomogeneously excited material. For a particular form of the inhomogeneity, a closed form solution is found which shows that the optical gain measured by optical pumping experiments will be less than the “intrinsic” gain which would be observed in a homogeneously excited material.

Experimental and theoretical electron-beam-sustained CO2 laser output at ∼200 and ∼300 °K

A six-temperature kinetic model of the He : He2Co2 : N2 : CO laser system is developed, in which five temperatures describe the vibrational excitation of the three CO2 modes, N2, and CO, while the sixth refers to the kinetic temperature. Theoretical predictions of gain and laser output are compared with experiments performed on an electron-beam sustainer laser used at atmospheric pressure. Gain and laser measurements have been made with initial gas temperature near 200 and 300 °K. A stable discharge can be produced in this type of laser in gas mixtures containing no He, and successful electric laser operation has been demonstrated using H2 as CO2ν2 deactivant. Various gas mixtures have been investigated experimentally and theoretically; specific output J≳100 J/liter atm was obtained both in He : N2 : CO2 : H2 3 : 2 : 1 : 0 and 0 : 3 : 1 : 0.08, with efficiencies near 30%. While the gain measured appears to peak later and decay later than predicted, in all laser output measurements there is good agreement between theoretical prediction and experiment.