Measurements Of Microwave Radiation Research Articles

Design of microwave applicator for processing biomass waste

Activated carbon is produced by microwave heating method. We designed microwave applicator for processing biomass waste into activated carbon. To obtain the optimal design, CST Microwave studio was selected to simulate microwave radiation inside the applicator. In this work, simulation process has been done to find out microwave radiation with the change a waveguide port position and microwave cavity shape. In the measurement of microwave radiation, we used electrical field (E-field) monitor at frequency 2.45GHz. The result shows that applicator with hexagonal shape has the best performance in power accepted and power outgoing, most uniform E-field radiation in the sample. Microwave applicator for heating process biomass waste into activated carbon can be optimized with adding some stirrer mode.

Cross-validation of two liquid water path retrieval algorithms applied to ground-based microwave radiation measurements by the RPG-HATPRO instrument

ABSTRACTA built-in operational regression algorithm (REA) of liquid water path (LWP) retrieval supplied by the manufacturer of the RPG-HATPRO microwave (MW) radiometer has been compared to a so-called physical algorithm (PHA) based on the inversion of the radiative transfer equation. The comparison has been performed for different scenarios of MW observations by the RPG-HATPRO instrument that has been operating at St. Petersburg University since June 2012. The data for the scenarios have been collected within the time period December 2012–December 2014. The estimations of bias and random error for both REA and PHA have been obtained. Special attention has been paid to the analysis of the quality of the LWP retrievals before and after rain events that have been detected by the built-in rain sensor. The estimation has been done of the time period after a rain event when the retrieval quality should be considered as insufficient.

Measurement of microwave radiation from electron beam in the atmosphere

We report the use of an electron light source (ELS) located at the Telescope Array Observatory in Utah, USA, to measure the isotropic microwave radiation from air showers. To simulate extensive air showers, the ELS emits an electron beam into the atmosphere and a parabola antenna system for the satellite communication is used to measure the microwave radiation from the electron beam. Based on this measurement, an upper limit on the intensity of a 12.5GHz microwave radiation at 0.5m from a 1018 eV air shower was estimated to be 3.96×10−16 W m−2 Hz−1 with a 95% confidence level.

Retrieving cloudy atmosphere parameters from RPG-HATPRO radiometer data

An algorithm for simultaneously determining both tropospheric temperature and humidity profiles and cloud liquid water content from ground-based measurements of microwave radiation is presented. A special feature of this algorithm is that it combines different types of measurements and different a priori information on the sought parameters. The features of its use in processing RPG-HATPRO radiometer data obtained in the course of atmospheric remote sensing experiments carried out by specialists from the Faculty of Physics of St. Petersburg State University are discussed. The results of a comparison of both temperature and humidity profiles obtained using a ground-based microwave remote sensing method with those obtained from radiosonde data are analyzed. It is shown that this combined algorithm is comparable (in accuracy) to the classical method of statistical regularization in determining temperature profiles; however, this algorithm demonstrates better accuracy (when compared to the method of statistical regularization) in determining humidity profiles.

Online power transformer diagnostics using multiple modes of microwave radiation to reconstruct winding conductor locations

A novel approach to diagnostics of transformer winding deformations, caused by mechanical forces from short-circuit currents, is presented. We employ a simple model of a transformer as a two-dimensional parallel plate waveguide. The upper plate represents the transformer tank wall and the lower plate represents the iron core which carries the magnetic flux. Between the two plates, we model the transformer winding by a set of parallel conductors. We utilize commercial simulation software to simulate the generation and measurement of microwave radiation at both ends of the winding structure. The radiation interacts with the metallic structures in the model waveguide. The measured responses from the model waveguide are expected to be sensitive to mechanical deformations of the transformer winding. We use conventional waveguide theory to solve the direct propagation problem, and an optimization method to solve the inverse problem. In particular, we determine the locations of winding segments, and obtain a good agreement between reconstructed and true conductor positions.

Multiparameter technique for interpreting ground-based microwave spectral measurements in the problem of ozone vertical profile retrieval

The algorithm for interpreting ground-based measurements of the brightness temperature of downwelling microwave radiation in absorption lines traditionally used for to retrieve ozone vertical profiles is described. The inverse problem is formulated as a multiparameter with respect to ozone vertical profile (target parameter), as well as vertical profiles of the temperature, pressure, water vapor content, and cloud liquid water (controlled parameters). This approach allows one to use independent measurements of atmospheric parameters in different altitude ranges (if available) in any combinations and accounting for physical relationships between the parameters (e.g., the hydrostatic equation for temperature and pressure). Error estimates for retrieving the mean ozone concentration in the 22–30-, 30–40-, 40–50-, and 50–60-km layers are presented for summer and winter conditions (for different tropospheric total water content) and different scenarios of interpreting the downwelling microwave radiation measurements in the 110-GHz ozone absorption line.

Analysis and Characterization of the SSMIS Upper Atmosphere Sounding Channel Measurements

Analyses and results of the radiometric calibration accuracy and measurement characteristics of the first Defense Meteorological Satellite Program (DMSP)'s Special Sensor Microwave Imager/Sounder (SSMIS) upper atmosphere sounding (UAS) channels are presented herein. Launched on October 18, 2003, aboard the DMSP F-16 spacecraft in a sun-synchronous orbit, the SSMIS UAS channels provide the first operational measurements of microwave radiation emitted by the Earth's atmosphere at mesospheric altitudes. The analysis of the SSMIS radiometer absolute calibration and stability is based upon extensive comparisons with a fully polarimetric radiative transfer model (RTM) that solves for all four Stokes parameters using coincident atmospheric temperature profiles derived from collocated Rayleigh lidar observations merged with the European Centre for Medium-Range Weather Forecasting temperature analyses and climatological data sets. The resulting merged profiles provide a physically consistent temperature profile from the surface to 100 km, as needed by the RTMs. The results presented herein of the SSMIS instrument show that significant hardware and scientific technical challenges arise from microwave temperature sounding of the mesosphere. These include the following: 1) addressing the impact of large noise-equivalent temperature difference associated with narrow channel bandwidths; 2) achieving high channel center-frequency stability; 3) compensation of large spacecraft-induced Doppler shift; 4) better characterization of the Zeeman splitting of the oxygen absorption lines; 5) development of a fast polarimetric RTM; and 6) designing stable and accurate on-orbit radiometric calibration targets. Results to date show that the uncertainties of the calibration accuracy of the SSMIS UAS channels are consistent and in agreement with the limits derived for the SSMIS UAS channels and with the simulated radiances derived from the merged lidar profiles.

Long range transport and fate of a stratospheric volcanic cloud from Soufrière Hills volcano, Montserrat

Abstract. Volcanic eruptions emit gases, ash particles and hydrometeors into the atmosphere, occasionally reaching heights of 20 km or more, to reside in the stratospheric overworld where they affect the radiative balance of the atmosphere and the Earth's climate. Here we use satellite measurements and a Lagrangian particle dispersion model to determine the mass loadings, vertical penetration, horizontal extent, dispersion and transport of volcanic gases and particles in the stratosphere from the volcanic cloud emitted during the 20 May 2006 eruption of Soufrière Hills volcano, Montserrat, West Indies. Infrared, ultraviolet and microwave radiation measurements from two polar orbiters are used to quantify the gases and particles, and track the movement of the cloud for 23 days, over a distance of ~18 000 km. Approximately, 0.1±0.01 Tg(S) was injected into the stratosphere in the form of SO2: the largest single sulphur input to the stratosphere in 2006. Microwave Limb Sounder measurements indicate an enhanced mass of HCl of ~0.003–0.01 Tg. Geosynchronous satellite data reveal the rapid nature of the stratospheric injection and indicate that the eruption cloud contained ~2 Tg of ice, with very little ash reaching the stratosphere. These new satellite measurements of volcanic gases and particles can be used to test the sensitivity of climate to volcanic forcing and assess the impact of stratospheric sulphates on climate cooling.

Derivation of a root zone soil moisture algorithm and its application to validate model data

A retrieval algorithm for soil moisture within the uppermost metre of soil is presented. As calibration data, longtime soil moisture measurements from the former Soviet Union are used. The retrieval works in two steps. First, the distribution of longtime mean soil moisture is derived by using precipitation, soil texture, vegetation density and terrain slope. In a second step, the temporal variability at each location is deduced by using microwave radiation measurements available from satellite together with precipitation and air temperature data. This soil moisture algorithm is applied in Northern and Central Europe to validate a climate simulation from the regional model REMO.

Up‐scaling effects in passive microwave remote sensing: ESTAR 1.4 GHz measurements during SGP '97

Passive microwave radiation measurements over sparsely vegetated surfaces during the Southern Great Plain Experiment are used to determine spatial up‐scaling effects. For various distributions of geophysical parameters, the differences between mean soil moisture derived from high resolution (800 by 800m²) 1.4 GHz brightness temperatures and soil moisture calculated from mean brightness temperatures at larger scales are compared. For spatial resolutions of 31.4²km², the effects of these non‐linearities in radiative transfer at 1.4 GHz do not yield differences in estimated volumetric surface soil moisture (0–5 cm) exceeding 0.02 [cm³cm−3].

Satellite estimation of precipitation over land

The availability of satellite-derived rainfall products to hydrologists and other natural scientists has increased enormously in the last five years. The purpose of this paper is to review concisely the current state-of-the-art of satellite precipitation estimation over land and the availability of standard products, and to highlight some of the strengths and limitations of satellite-derived rainfall data for hydrological applications. Methods based on infrared, visible and passive microwave radiation measurements are discussed. Results of several international activities aimed at evaluating the performance of the estimation algorithms are briefly summarized.

Determination of ocean surface temperature taking account of atmospheric effects by measurements of the angular IR‐radiation distribution of the “ocean‐atmosphere” system made from the satellite “cosmos‐1151”

A comparative analysis of the multispectral and angular methods of surface temperature determination, is presented. The measurements of the thermal radiation in 11.1 μm window region which are fulfilled under three angles along satellite tracks are used for zero air mass extrapolation. In the comparison of simultaneous IR and microwave radiation measurements, with the ship temperature valves, shows that in most cases the 1k accuracy is achieved.

Microwave radiation from water surface as related to its temperature variations in the presence of ripples (a laboratory study)

In this paper the results are presented of measurements of microwave radiation at centimeter wavelengths from water surface under controllable laboratory conditions which included changes in the surface temperature and generation of ripples caused by wind and by ventilator with velocity of air stream up to 3 m/s.

Experimental study of microwave spectra emitted from a turbulent heated toroidal discharge

Spectrally resolved measurements of microwave radiation in the frequency range 8-170 GHz from the toroidal machine with turbulent heating, TORTUR, are reported. Spectral resolution was obtained using a ten-channel microwave multiplexer (8-40 GHz), and a far-infrared grating spectrometer (50-170 GHz). Plasma conditions were varied such that 10 GHz< omega ce<50 GHz, and 60 GHz< omega pe<140 GHz, for various choices of the plasma current (up to 200 kA) and electric field strength (1 kV/m<E<5 kV/m). At low frequencies ( omega <or approximately= omega ce), the spectra obtained show evidence for Cerenkov beam-plasma type instabilities, corresponding to the unstable propagation of whistler modes along resonance cones. At higher frequencies, bursts of radiation near omega = omega pe are observed, as well as cyclotron radiation of thermal origin near 2 omega ce and 3 omega ce. The latter was used to give information on the electron temperature distribution, showing a high temperature in the turbulent skin region, followed by an extremely fast energy transport to the plasma core.

Measurement of microwave radiation absorbed by biological systems: 2. Analysis by Dewar‐flask calorimetry

Free‐field power density has long been used as an index of energy dosing in studies of biological effects of microwave radiation. However, this method of quantifying dose can lead to considerable error if it is used as an index of the rate of energy actually being absorbed by a specimen, because the relative absorption cross sections of different specimens may vary greatly. The integral of absorbed energy is a more meaningful measure of exposure; it can be accomplished by using such sophisticated equipment as twin‐well calorimeters, or by using the cruder system of saline‐filled phantoms This paper describes a calorimetric system for the measurement of absorbed energy in laboratory animals and in in vitro samples that can be assembled from such common laboratory equipment as Dewar flasks, magnetic stirrers, foamed polystyrene, and an accurate temperature measuring device. Measurements of absorbed energy by this system for a standard tissue‐culture flask are compared to values obtained by electrical measurements, by direct temperature measurements, and by heating and cooling curves. Also, application of the system to measurements of dose in experimental animals is demonstrated.

Measurement of microwave radiation absorbed by biological systems: 1. Analysis of heating and cooling data

In order for meaningful comparisons to be made between experiments from different laboratories, reliable dosimetry is needed for biological systems exposed to microwave radiation. We present an improved analytical method for determining energy absorption which uses heating and cooling curves. The method is demonstrated for in vitro samples that were exposed to microwave radiation in two different exposure systems. Advantages and disadvantages of the method, as well as practical considerations, are discussed.

Measurements of microwave radiation from turbulently heated plasmas

Intense microwave radiation from a turbulently heated plasma in a frequency range near the electron plasma frequency omega pe was observed and its relations with plasma resistance R were studied for two cases. When the plasma was highly resistive, (i) the power of microwave radiation at a frequency larger than omega pe was proportional to R2 in lower density region ( approximately 2.5*1013 cm-3), however (ii) the radiation power at a frequency smaller than Omega pe was proportional not to R2 but rather to R in higher density region ( approximately 6*1013 cm-3). The microwave radiation in the former case was emitted dominantly by non-linear coupling between waves in the plasma and the radiation in the latter case by linear conversion due to the density gradient.

Measurements of microwave radiation from turbulently heated plasmas

Intense microwave radiation from a turbulently heated plasma in a frequency range near the electron plasma frequency omega pe was observed and its relations with plasma resistance R were studied for two cases. When the plasma was highly resistive, (i) the power of microwave radiation at a frequency larger than omega pe was proportional to R2 in lower density region ( approximately 2.5*1013 cm-3), however (ii) the radiation power at a frequency smaller than Omega pe was proportional not to R2 but rather to R in higher density region ( approximately 6*1013 cm-3). The microwave radiation in the former case was emitted dominantly by non-linear coupling between waves in the plasma and the radiation in the latter case by linear conversion due to the density gradient.

An analysis of re-entry flight measurements of shock layer microwaveradiation

Free-flight radiometer measurements of shock layer microwave radiation at a frequency of 2235 Mcycles/sec are analyzed from a gas-dynamic viewpoint. From these measurements, which were carried out during the re-entry of a spherical nose, 9° cone at a nominal velocity of 18,000 fps, an effective plasma temperature is defined. Although a cursory examination of the data indicates general agreement with flowfield calculations, effective temperatures as much as 1500°K higher than the equilibrium stagnation temperature were obtained in the vicinity of the sphere-cone junction. Possible mechanisms which would account for these high-temperature values are considered; and it is proposed that it is the electron temperature overshoot in the stagnation region, coupled with a nearly frozen expansion from these conditions and around the body, that produces the observed excessive plasma temperatures. Theoretical calculations of the effective plasma noise temperature for the stagnation point antenna are also presented, and reasonable agreement is obtained. LTHOUGH the general nature of the flowfield around a blunt hypersonic vehicle is now well known, there still are many details which are not understood. This is particularly true of the physico-chemical phenomena that are present in the flow and the coupling of the associated processes with the fluid mechanic phenomena; and there is thus considerable research still in progress. This work is both of a theoretical and experimental character, and in the latter category includes free-flight as well as laboratory measurements. The present investigation is an outgrowth of a free-flight experimental program being conducted by the Electro-Science Laboratory of The Ohio State University. This program is designed for ballistic re-entry communication studies, and the details of the particular experiment to be discussed here will be summarized in the next section. Much of the data obtained have been from measurements of signal attenuation and reflection. However, the second vehicle in the test series was instrumented specifically for measurements of shock layer microwave radiation at a frequency of 2235 Mcycles/sec. This radiation is the result of Bremsstrahlung emission and is associated with the electron temperature of the gas. The data obtained from this flight experiment thus provides an opportunity to look at the thermal characteristics of the electrons in the flow; and it is the analysis of this data that is the subject of this paper. As noted, the details of the free-flight experiment itself and the data will be discussed in the next section. This will be followed in Sec. Ill by a discussion of the nature of the shock layer surrounding the vehicle in terms of the electron characteristics. Finally, in Sec. IV comparisons will be made between the free-flight microwave radiation measurements and

Upper Limits on Universal Microwave Radiation below λ = 1.7 mm

THE microwave radiation discovered by Penzias and Wilson1 fitted into the theory of the big-bang universe proposed by Gamow2 and Dicke et al.3, which predicts a residual radiation with a temperature of ∼ 3° K from the cooling of the primordial radiation. Measurement of the strength of the microwave radiation at different wavelengths4 and the inferred strength at 2.3 mm fitted the blackbody curve with a temperature of 2.7° K (Fig. 1). Supporters of the steady state universe5,6, however, are contesting this interpretation and suggest that the radiation may be the result of the superposition of “sources” or the scattering of source radiation by “dust grains”. At present, there are no direct experimental measurements of microwave radiation below a wavelength of 7 mm to show that the radiation is either a blackbody radiation of temperature 2.7° K or the type predicted by Narlikar and Wickramasinghe6. In this report I shall derive upper limits on the intensity of the microwave radiation below a wavelength of 1.7 mm using cosmic ray data to indicate the nature of the radiation.