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A microwave frequency interferometer sensor has been demonstrated to have the sensitivity and accuracy needed to characterize fluid stream clouds comprising both water and ice crystals for applications in wind tunnel testing. Considerations for in-flight sensing and measurement are suggested.
Simulation results for several novel shapes of dielectric inserts that can serve as effective process seals for a standard WR-90 waveguide-to-coax adapter are presented. The objective of the design is to modify a standard adapter as a convenient wave launching structure for the measurement of fields in the interior regions of a complex machine. Modifying the geometry of the process seal insert has...
The surface wave propagation along a closely-spaced folded cylindrical helix (FCH) array is investigated for the purpose of minimizing the size of the array element. It is found that the height of this surface wave guiding structure can be decreased from 0.24 λo to 0.06 λo by replacing the monopole with the folded cylindrical helix. The frequency band of the surface wave supported by the helix array...
Ultra-wideband signals are used to examine multiple-constituent fluid mixtures in a semi-open system. A feedforward neural network operates on an array of easily computed signal properties, plus the weight and temperature of the fluid samples, to provide an estimate of the constituent proportions. The average performance of the neural network is tested by artificially increasing the test data sample...
The surface wave propagation in a 1-D randomized metal wire array is studied using a simulation approach. First we establish the baseline of this research by simulating wideband transmission data and near electric fields for a uniform height, uniform spacing array. The surface wave propagation inside the array is identified and characterized. Then we perturb the wire element heights to investigate...
Previously a novel microwave measurement device known as the Guided Microwave Spectrometry (GMS) system was developed which proved capable of non-destructively measuring the composition of various mixtures of known constituents [Jean, IEEE Transactions on Instrumentation and Measurement, Vol. 55, No. 1, 180–186, 2006]. It operates by measuring the cut-off and passband responses of a section of rectangular...
An ultra-wide band pulse transceiver has been developed using integrated circuits which demonstrates a tunable 10dB bandwidth from 1.4 GHz to 3.3 GHz. The transceiver has a synchronous receiver which demodulates and extends the pulse in time using Equivalent Time Sampling (ETS) techniques. Equivalent time sampling has been shown to accurately reconstruct the RF pulse with an ETS factor up to 1.5 million...
With the widespread use of high-voltage GaN devices and other high-power transistors, understanding the heating of a device during large-signal excitation and measurement is critical, both to ensure efficient operation and to prevent destruction of devices during measurement. Device self-heating during RF excitation is directly dependent upon the power-added efficiency of operation. All DC and RF...
A low cost pulse transceiver has been developed for measuring the electrical properties of materials. The transceiver generates an ultra wide band (UWB) pulse as well as samples the received pulse. The pulse generator has been designed using a silicon-germanium (SiGe) analog comparator which is a possible alternative to step recovery diodes. The pulse is received by an extended time sampling circuit...
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