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7 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

2. 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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3. 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

4. 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

5. 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

6. 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

7. 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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