RF & Microwave Electronics

Tiny Graphene Radios May Lead to Internet of Nano-Things

This image shows graphene-based nanoantennas (blue and red dots) on a chip. (Credit: University at Buffalo) For wireless communication, we’re all stuck on the same traffic-clogged highway — it’s a section of the electromagnetic spectrum known as radio waves. Advancements have made the highway more efficient, but bandwidth issues persist as wireless devices proliferate and the demand for data grows. The solution may be a nearby, mostly untapped area of the electromagnetic spectrum known as the terahertz band.

Posted in: News, RF & Microwave Electronics

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Chalcogenide Nanoionic-Based Radio Frequency Switch

The electrochemical switch is non-volatile, lacks moving parts that can fail, and is easy to fabricate.NASA’s Glenn Research Center has developed nanoionic-based radio frequency (RF) switches for use in devices that rely on low-power RF transmissions, such as automotive systems, RFID technology, and smartphones. These groundbreaking nanoionic switches operate at speeds of semiconductor switches, and are more reliable than microelectromechanical systems (MEMS) switches while retaining the superior RF performance and low power consumption found in MEMS, all without the need for higher electrical voltages. In this new process, metals are photo-dissolved into a chalcogenide glass and packaged with electrodes and a substrate to form a switch. Since the nanoionic-based switch is electrochemical in nature, it has certain advantages over switches that are mechanically based, including nonvolatility, lack of moving parts that can fail, ease and efficiency of activation, and ease of fabrication. This innovative device has the potential to replace MEMS and semiconductors in a wide range of switching systems, including rectifying antennas (rectennas) and other RF antenna arrays.

Posted in: Briefs, Electronic Components, Electronics & Computers, RF & Microwave Electronics

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New Algorithm Reveals Underground Water Levels

Researchers from Stanford University have used satellite data and a new computer algorithm to gauge groundwater levels in Colorado’s San Luis Valley agricultural basin. The technique "fills in" underground water levels in areas where quality data had been previously unavailable.

Posted in: News, Imaging, Visualization Software, Antennas, RF & Microwave Electronics

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High-Data-Rate Platform to Capture and Analyze Raw Baseband Clock/Data

NASA’s Jet Propulsion Laboratory, Pasadena, California The Space Communications and Navigation (SCaN) Testbed has a need to capture and analyze high-datarate (<2 Mbps required) baseband information sent over RF by the JPL Software-Defined Radio (SDR). An RF4425 front end, coupled with a MicroGate Synclink USB and custom C++ software back end, is being used to answer this need.

Posted in: Briefs, RF & Microwave Electronics

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V-FASTR Radio Transient Classifier

NASA’s Jet Propulsion Laboratory, Pasadena, California The V-FASTR (VLBA Fast Transient Experiment) system was motivated by the desire to monitor the radio sky for interesting transient events. To be confident that no interesting extragalactic event is missed, every VFASTR candidate requires human review and evaluation. Candidates consist of pulsar pulses, spurious correlated radio frequency interference (RFI), and other potentially unknown phenomena. However, the number of candidates generated by V-FASTR each day ranges from zero, to tens, to hundreds, to thousands, depending on the observational target and environmental conditions. On busy days, the volume of candidates exceeds the amount of time available for human review.

Posted in: Briefs, RF & Microwave Electronics

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Wideband, Dual-Polarized, Ultra-Low-Noise Focal Plane Array Feed for Active/Passive Microwave Remote Sensing

Goddard Space Flight Center, Greenbelt, Maryland NASA missions utilize active, passive, or both, microwave sounders with a large reflector antenna as an important component. In most of these applications, design engineers have realized that desirable science requirements (spatial and temporal resolutions) can be met only by compromising between conflicting engineering design parameters. A microwave remote sensor designed to achieve high spatial resolution would result in longer revisit time, yielding low temporal resolution and vice-versa. To overcome these conflicting requirements, the present technology advocates use of a cluster of feed horns arranged in the focal plane of the primary reflector antenna. Each feed horn produces a different footprint with appropriate overlaps covering a wide swath, allowing a high temporal resolution. Each feed horn, since they act independently, is designed to produce high spatial resolution. However, this approach has many disadvantages compared to an antenna system in which the cluster of horn feeds is made to act as a Focal Plane Array (FPA). Furthermore, the current approach does not enable maximization of the antenna gain, or immunity for radio frequency interference (RFI).

Posted in: Briefs, RF & Microwave Electronics

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RF Source Modifications to Improve Performance of an Electronegative Plasma Thruster

Marshall Space Flight Center, Alabama In traditional gridded electrostatic ion thrusters, positively charged ions are generated from a plasma discharge of noble gas propellant and accelerated to provide thrust. A separate electron source, typically a neutralizer cathode that consumes propellant, is required in the propulsion system to neutralize the ion beam after it exits the thruster, thereby maintaining overall charge balance. However, if high-electronegativity propellant gases are used, a plasma discharge can result that consists of both positive and negative ions. Such an electronegative plasma thruster has the ability to generate thrust with a quasi-neutral ion-ion plume, thus allowing for the elimination of the neutralizer cathode subsystem, reduction of propulsion system complexity, and improvement of system lifetime and operational flexibility.

Posted in: Briefs, RF & Microwave Electronics

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