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The Microwave Humidity and Temperature Sounder, MWHTS, is being developed to fly on the new generation of FengYun polar orbiters, which is named FY-3D and due to be launched in the latter half of 2016. MWHTS with 15 channels in the range of 89 ∼ 190 GHz is designed for atmospheric humidity and temperature sounding, and also for monitoring severe weather systems such as typhoons and rainstorms. Before...
Cancer is one of the leading cause of death worldwide, and an early detected cancer is likely to get better treatment. Widely used modalities for scanning the presence of cancer such as Computed Tomography and Magnetic Resonance Imaging still have problems related to the cost, size and equipment complexity. Microwave imaging is considered as an alternative modality due to its low health risk, low...
In this work, we demonstrated the effects on reflection loss (RL) for a microwave absorbing coating. The mixture of an absorbing coating before curing process including flake carbonyl iron particles (FCIPs), polymer matrix, and moderate diluting agent butanone were distributed uniformly. Microwave absorption properties RL of the coating were measured during curing process at the frequency range of...
This paper describes a method to heat a food uniformly by using a microwave oven which has two input ports. Different standing wave distribution appears when an in-phase or anti-phase electric power is excited in the two input ports. This means that the heated parts of a food are different. Therefore, it is possible to heat a food more uniformly when in-phase or anti-phase electric power is given...
Recent years has witnessed a growing interest in the research for featured-enhanced high-resolution microwave imaging field. The existing methods for radar image process are classified into image processing and target classification. Though these methods can effectively improve the imaging quality, the fact we have to meet is that lots of useful image information would be discarded in the procedure...
Active and passive microwave remote sensing data holds great potential for soil moisture estimation. Herein, the application of the Least Squares Support Vector Machines (LS-SVM) to soil moisture inversion is explored. Simulation is carried out using different sets of training and test data. The methods have been applied to two sets of data to retrieve bare-surface soil moisture, and the rms error...
In this paper the implementation of the Sparse or Compressed Sensing (CS) technique to subsurface holography allowing data acquisition on a sparse grid is considered, which raises the scanning speed, reduces the amount of stored and transmitted data. To test various aspects of applying CS technique, a custom-built experimental setup acquiring data at several programmable sampling intervals was used...
This work presents an analysis and optimization of a microstrip wideband switching system for a 16×16 three-dimensional microwave imaging sensor array. Microwave switching system, or RF multiplexer, is necessary for microwave imaging system because of the limited transmitting/receiving port and multiple antenna elements. Using compact RF switches, a switching system selects and connects each of the...
The discontinuous Galerkin time-domain (DGTD) method is gaining popularity among computational electromagnetics (CEM) practitioners. This can be attributed to the fact that it has several advantages over the classical finite element method. The DGTD method realizes “information exchange” between neighboring spatial discretization elements using numerical flux. Therefore all spatial operations are...
Surface plasmon polaritons (SPPs) are two-dimensional electromagnetic (EM) fields, which are highly localized, propagate along metal-dielectric interfaces, and decay exponentially into adjacent media. Owing to the advantages of confined EM fields in subwavelength scales, SPPs have a lot of potential applications in super-resolution imaging, miniaturized sensors, and biosensing. Recently, in the microwave...
We experimentally demonstrate optical theorem can be employed to obtain the scattering cross-section (SCS) for transformation media. Different from the total scattering-field integration approach, the optical theorem method is a transmission-like measurement for SCS characterization, and furthermore facilitates accessing the broadband spectrum for bandwidth evaluation. In order to examine this measurement...
Frequency selective surfaces (FSSs) are planar structures composed of a periodic array of unit cells that filter electromagnetic (EM) waves impinging on the surfaces. They have been widely used in stealth technology, electromagnetic countermeasure, and communication systems [1, 2]. Typical FSSs are composed of metallic grids or dipole arrays, which exploit the strong interactions between EM waves...
Selective wave-transmitting absorbers (STAs), which have one or more narrow transmission bands among a wide absorption band are often demanded in wireless communication and stealth technology. They can be used in many applications such as reducing antennas' radar cross section, reducing the coupling between different systems and improving anti-jamming capability. However it is difficult to realize...
In this paper, a novel analogue tunable bandpass filter with constant absolute bandwidth is presented. The filter is designed based on full wavelength microstrip open ring resonators loaded with varactors. Magnetic dominated mixed coupling is designed to make the coupling coefficient meet the requirement of constant absolute bandwidth response. The filter is designed, fabricated and measured. The...
The effect of environmental pressure of reflection and transmission coefficients of the solid rocket plume at 2000K region is studied by using the propagation matrix method. The complex relative permittivity of dusty plasma, the concept of charging response factor and the propagation matrix method are introduced in this paper. The change of environment pressure will induce variation in the electron...
A method to enhance microwave tomography through the use of an inhomogeneous background is proposed. Here, the measurement region is located in a circular perfect electrical conductor (PEC) chamber where known objects are placed inside the imaging domain as an inhomogeneous background. The Green function of a circular PEC chamber with inhomogeneous background is obtained using the method of moments...
In this paper, we present a laboratory prototype of POP atomic clock with dispersive detection developed at Shanghai Institute of Optics and Fine Mechanics (SIOM). A new physics package is designed in order to improve the homogeneity of the H-field orientation. The Ramsey fringe is presented with an ultrahigh contrast of 91% and line-width of 130 Hz. A clock frequency stability of 6.14 × 10−13 @1...
Usual method to investigate high frequency parameters of the microwave diodes is to mount the single diode into microwave transmission line with following measurements of the detected voltage, for example. However, this is a time consumable process. Time savings can be achieved using RF probes for the detection measurements. We present investigation of detection of microwaves signals using heterojunction...
Active microwave remote sensing is a promising tool for global snow water equivalent mapping. However, many studies have shown that extra information is needed to estimate the snow water equivalent accurately. The most important problem is to characterize the snow grain size and to quantitatively separate the effect of grain size and snow mass on backscattering magnitude. In this study, QuikScat backscattering...
Due to the low spatial resolution of passive microwave sensors, the spatiotemporal heterogeneity of snow parameters may be the primary factor influencing the inversion accuracy. However, at present, continuous observations of snow parameters are rare due to the limited automation of snow monitoring equipment. In this study, a passive microwave pixel is selected as the experimental region, and detailed...
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