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41 results on '"Rodriguez-Morales, F."'

1. An UWB UHF Ice-Penetreating Radar for the Thwaites Melt Project

Author

Rodriguez-Morales, F., Paden, J., Escalera Mendoza, A. S., Hale, R., Karidi, K. T., Schroeder, B., Shang, J., Talasila, H., Robinson, C., Jordan, T., Nicholls, K., Rodriguez-Morales, F., Paden, J., Escalera Mendoza, A. S., Hale, R., Karidi, K. T., Schroeder, B., Shang, J., Talasila, H., Robinson, C., Jordan, T., and Nicholls, K.

Abstract

As a part of the project "Melting at Thwaites grounding zone and its control on sea level" (MELT), we developed a compact 750-MHz ice-penetrating radar for phase-sensitive measurements to infer basal melt and ice layer displacement using multiple passes. The radar operates with 300-MHz bandwidth and a peak output power of 400 W. It is equipped with a small antenna array designed to fit within the limited space underneath the floor of a Twin Otter aircraft (without out-of-mold-line protuberances). The radar was installed and deployed onboard a Twin Otter airplane from the British Antarctic Survey (BAS) as a part of the ongoing International Thwaites Glacier Collaboration (ITGC). We conducted multiple radar survey flights during two consecutive austral summer seasons, collecting ~5 TB of raw data. In this paper, we present an overview of the radar system and antenna implementations. We provide a summary of our field operations and present sample data products to illustrate the instrument capabilities to sound ice as thick as ~1,400 m and map internal reflecting horizons near the grounding line of TG with sub-m vertical resolution. We also discuss the utility of our repeat pass data for inferring ice shelf basal melt rates.

Published
2024

3. Direct and Heterodyne Detection of Microwaves in a Metallic Single Wall Carbon Nanotube

Author

Rodriguez-Morales, F., Zannoni, R., Nicholson, J., Fischetti, M., Yngvesson, K. S., and Appenzeller, J.

Subjects
Condensed Matter - Mesoscale and Nanoscale Physics, Condensed Matter - Materials Science
Abstract

This letter reports measurements of microwave (up to 4.5 GHz) detection in metallic single-walled carbon nanotubes. The measured voltage responsivity was found to be 114 V/W at 77K. We also demonstrated heterodyne detection at 1 GHz. The detection mechanism can be explained based on standard microwave detector theory and the nonlinearity of the DC IV-curve. We discuss the possible causes of this nonlinearity. While the frequency response is limited by circuit parasitics in this measurement, we discuss evidence that indicates that the effect is much faster and that applications of carbon nanotubes as terahertz detectors are feasible.

Published
2006
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4. Wideband IF-integrated terahertz HEB mixers: modeling and characterization

Author

Rodriguez-Morales, F., Yngvesson, K.S., and Dazhen Gu

Subjects
Amplifiers, Audio -- Design and construction, Bandwidth -- Measurement, High-electron-mobility transistors -- Analysis, Niobium -- Electric properties, Bandwidth allocation, Bandwidth technology, Business, Computers, Electronics, Electronics and electrical industries
Published
2010

7. A Compact Multi-Channel Radar for >1Ma Old Ice Core Site Identification in East Antarctica

Author

Rodriguez-Morales, F., primary, Carswell, J., additional, Gogineni, P., additional, Taylor, R., additional, Yan, J., additional, Abe-Ouchi, A., additional, Fujita, S., additional, Kawamura, K., additional, Tsutaki, S., additional, Liefferinge, B. Van, additional, Matsuoka, K., additional, Ailon, H., additional, Alvarez, S., additional, Braaten, D., additional, Karidi, K.T., additional, Paden, A., additional, Paden, J., additional, Shang, J., additional, and Akins, T., additional

Published
2019
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10. Ultra-Wideband Radars for Measurements over Land and Sea Ice

Author

Hale, Richard, Miller, Heinrich, Gogineni, S., Yan, J.-B., Rodriguez-Morales, F., Leuschen, C., Wang, Z., Paden, John, Gomez-Garcia, D, Binder, Tobias, Steinhage, Daniel, Gehrmann, Martin, and Braaten, David

Abstract

We developed two ultra-wideband (UWB) radars for measurements over ice sheets in Greenland and Antarctica, and sea ice. One of the UWB radars operates over the frequency range of 150-600 MHz with a large cross-track 24-element array. It is designed to sound ice, image ice-bed interface and map internal layers with fine resolution. The 24-element-array consists of three 8-element sub-arrays. One of these sub-arrays is mounted under the fuselage and the other two are mounted under the wings of BT-67 aircraft. The measured inflight VSWR is less than 2 over the entire operating range. The fuselage sub- array is used both for transmission and reception, and wing-mounted sub-arrays are used for reception. The transmitter consists of 8-channel digital waveform generator to synthesize chirped pulses of selectable pulse width and duration. It also consists of driver and power amplifiers to increase the power level to about 1 kW and a fast transmit/receive switch that can handle more than 1 kW of peak power. Each receiver consists of a limiter, switches, low-noise and driver amplifiers, and filters to shape and amplify received signals to the level required for digitization. The digital sub-section consists of timing and control sub-system, and 24-A/D converters to digitize received signals at a rate of 1.6 GHz. The radar performance is evaluated using a delay line to simulate returns from about 2 km thick ice and the loop sensitivity is more than 215 dB. The other UWB microwave radar operates over the frequency range of 2-18 GHz in the Frequency-modulated Continuous Wave (FM-CW) mode. It is designed to sound more than 100 cm snow over sea ice and map internal layers to a depth about 25-40 m in polar firn and ice. We operated the microwave radar over snow-covered sea ice and mapped snow as thin as 5 cm and as thick as 60 cm. With an early version of the radar we mapped internal layers to a depth of 45 m with fine resolution in West Antarctica. We will discuss design considerations and present laboratory results to document radars performance including their impulse response functions. We will show the results from a field campaign over the Greenland ice sheet.

Published
2015

12. Multi-channel ultra-wideband radar sounder and imager

Author

Hale, R., primary, Miller, H., additional, Gogineni, S., additional, Yan, J. B., additional, Rodriguez-Morales, F., additional, Leuschen, C., additional, Paden, J., additional, Li, J., additional, Binder, T., additional, Steinhage, D., additional, Gehrmann, M., additional, and Braaten, D., additional

Published
2016
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13. Ultra-wideband radars for measurements over ICE and SNOW

Author

Gogineni, S., primary, Yan, J.-B., additional, Gomez-Garcia, D., additional, Rodriguez-Morales, F., additional, Leuschen, C., additional, Wang, Z., additional, Paden, J., additional, Hale, R., additional, Arnold, E., additional, and Braaten, D., additional

Published
2015
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14. Advanced Multifrequency Radar Instrumentation for Polar Research

Author

Rodriguez-Morales, F., Gogineni, S., Leuschen, C.J., Paden, J.D., Li, J., Lewis, C.C., Panzer, B., Gomez-Garcia Alvestegui, D., Patel, A., Byers, K., Crowe, R., Hale, R.D., Panton, Christian, Rodriguez-Morales, F., Gogineni, S., Leuschen, C.J., Paden, J.D., Li, J., Lewis, C.C., Panzer, B., Gomez-Garcia Alvestegui, D., Patel, A., Byers, K., Crowe, R., Hale, R.D., and Panton, Christian

Published
2014

29. Bed topography of Jakobshavn Isbræ, Greenland, and Byrd Glacier, Antarctica.

Author

YAN, J.-B., PADEN, J., LI, J., RODRIGUEZ-MORALES, F., WANG, Z., GOGINENI, S., LEUSCHEN, C., PURDON, K., BRAATEN, D., LIU, W., and GAUCH, J.

Subjects
GLACIERS, BYRD Glacier (Antarctica), GROUND penetrating radar, REMOTE sensing, GLACIOLOGY, EQUIPMENT & supplies
Abstract

This paper presents the bed topography of Jakobshavn Isbræ, Greenland, and Byrd Glacier, Antarctica, derived from sounding these glaciers with high-sensitivity radars. To understand the processes causing the speed-up and retreat of outlet glaciers, and to enable the development of next-generation ice-sheet models, we need information on bed topography and basal conditions. To this end, we performed measurements with the progressively improved Multichannel Coherent Radar Depth Sounder/Imager (MCoRDS/I). We processed the data from each antenna-array element using synthetic aperture radar algorithms to improve radar sensitivity and reduce along-track surface clutter. We then applied array and image-processing algorithms to extract the weak bed echoes buried in off-vertical scatter (cross-track surface clutter). At Jakobshavn Isbræ, we observed 2.7 km thick ice ~30km upstream of the calving front and ~850m thick ice at the calving front. We also observed echoes from multiple interfaces near the bed. We applied the MUSIC algorithm to the data to derive the direction of arrival of the signals. This analysis revealed that clutter is dominated by the ice surface at Jakobshavn Isbræ. At Byrd Glacier, we found ~3.62km thick ice, as well as a subglacial trench ~3.05km below sea level. We used ice thickness information derived from radar data in conjunction with surface elevation data to generate bed maps for these two critical glaciers. The performance of current radars must be improved further by ~15 dB to fully sound the deepest part of Byrd Glacier. Unmanned aerial systems equipped with radars that can be flown over lines spaced as close as 5m apart in the cross-track direction to synthesize a two-dimensional aperture would be ideal for collecting fine-resolution data over glaciers like Jakobshavn near their grounding lines. [ABSTRACT FROM AUTHOR]

Published
2014
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30. Prototyping an UWB Airborne Radar for Snow Probing Using Modular Building Blocks.

Author

Rodriguez-Morales, F., Carabajal, C., Paden, A., Leuschen, C., McDaniel, J., Wolf, A., and Garrison, S.

Subjects
*ULTRA-wideband radar, *RADAR in aeronautics, *ULTRA-wideband communication, *SNOW, *SYNTHETIC aperture radar, *LOW noise amplifiers, *ELECTRONIC probes, *ULTRA-wideband devices
Abstract

The article offers information related to ultra-wideband (UWB) airborne radar for snow probing using modular building blocks. Topics discussed include that the modules are based on tailored microwave filters, off-the-shelf building blocks from a commercial supplier and custom direct current biasing circuits; and integration of microwave components using this technique to enable evaluation of different configurations to improve radar performance.

Published
2019

31. Highly Packaged Terahertz Down-Converter Modules Using 3-D Integration.

Author

Rodriguez-Morales, F., Yngvesson, K.S., Dazhen Gu, Nicholson, J., Kan Fu, and Chak Chan

Abstract

This letter describes the design of highly packaged heterodyne receivers for terahertz applications. The 3-D integration of a terahertz mixer with a low-noise intermediate frequency amplifier is implemented for the first time using off-the-shelf components. Thereby, an-order-of-magnitude volume and weight reduction are accomplished. We validate our packaging approach experimentally, demonstrating performance comparable to that of a similar receiver assembled with planar interconnects. These 3-D receivers can in principle constitute the basis of close-fitting, densely populated focal plane arrays. [ABSTRACT FROM PUBLISHER]

Published
2007
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32. A terahertz focal plane array using HEB superconducting mixers and MMIC IF amplifiers.

Author

Rodriguez-Morales, F., Yngvesson, K.S., Gerecht, E., Wadefalk, N., Nicholson, J., Dazhen Gu, Xin Zhao, Goyette, T., and Waldman, J.

Abstract

We present a focal plane array (FPA) designed for operation at terahertz frequencies. The FPA is based on NbN phonon-cooled hot electron bolometer mixers directly coupled to wide-band microwave monolithic integrated circuit IF amplifiers. The array incorporates all the required dc-bias and IF circuitry in a compact split-block design. We present new experimental results describing the optical coupling efficiency to the array, as well as receiver noise temperature measurements. The measurements were performed at 1.6 THz, showing good agreement with theoretical predictions. This is the first low-noise heterodyne focal plane array to be reported for any frequency above 1 THz. [ABSTRACT FROM PUBLISHER]

Published
2005
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33. T/R Switches and Modules for Ice Sounding/lmaging Radar.

Author

Rodriguez-Morales, F., Gogineni, S., Alimed, F., Carabajal, C., Paden, A., Leuschen, C., Paden, J., Li, J., Fields, W., and Vaughan, J.

Subjects
*SWITCHING systems (Telecommunication), *RADIO frequency imaging, *RADIO frequency, *RADAR, *DIODES
Abstract

High-power transmit/receive (T/R) switches for use in multi-channel ice-penetrating imaging radars are capable of sustaining peak power levels exceeding 1000 W. They are based on a balanced topology and built using quadrature hybrids and actively biased PIN diodes. Insertion loss is lower than 1.3 dB from 100 to 350 MHz and lower than 1.6 dB from 150 to 600 MHz. Isolation in transmit mode is higher than 85 dB across both bands with turn-on and turn-off times shorter than 1300 ns and 200 ns, respectively. Both designs were successfully used in multichannel radars for measurements in the Arctic and Antarctic. [ABSTRACT FROM AUTHOR]

Published
2016

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