• At about $200, ideal as a low cost option for radio frequency receivers for astronomical observations
  • Designed for economical production and rapid, on-site assembly by relatively untrained personnel for use in arrays of antennas
  • Can operate independently or as part of a long wavelength array for astronomical radio telescope applications

NRL's Invention

Economical Low Frequency (LF) Active Antenna
Economical Low Frequency (LF) Active Antenna
  • Patent-pending active antenna design with fixed ground screen
  • Satisfies emerging need for a receptor that’s low-cost, operates at 6 dB sky noise dominated performance , has dual-polarization HF/VHF, and operates at 20-80 MHz
  • Optimized for economical manufacture and designed for untrained personnel to simply "stake down the antenna"
    • Single vertical support mast
    • Integrated front-end electronics on support mast
    • Two crossed-dipole antennas attached at orientation of about 90 degrees to each other
  • Each antenna has two arms made of electrically conductive material. Each arm has:
    • Triangular frame with apex connected to the feed points of the front end electronics unit
    • Longitudinal member extending from apex to center of the base of the triangular shape
    • Cross members extending between sides of the triangular frame

Testing/Validation at NRL

The NRL low-band antenna is optimized for ease of assembly without the need for specialized knowledge.  It is shown here being assembled by students.
The NRL low-band antenna is optimized for ease of assembly without the need for specialized knowledge. It is shown here being assembled by students.

NRL is a major partner in the Long Wavelength Array (LWA) project, a low-frequency radio telescope designed to produce high-sensitivity, high-resolution images in the lowest frequencies (20-80 MHz). NRL's Economical LF Active Antenna has been thoroughly tested at the first LWA station.

Opportunities for Commercial/Government Application

The NRL RSD-developed Low Band Antennas deployed at the first Long Wavelength Array station (LWA-1)
The NRL RSD-developed Low Band Antennas deployed at the first Long Wavelength Array station (LWA-1)

At about $200, the Economical LF Active Antenna is ideal for:

  • Professional and amateur astronomers who want to observe a variety of celestial objects and phenomena
  • Passive, all-sky imaging for military applications and detection of nuclear tests through observations of the ionosphere
  • Low-cost surveillance receptor for airborne objectives
  • General purpose, upward-looking high-sensitivity LF receptor

Demonstrated Demand

The Milky Way shines over the NRL RSD-developed Low Band Antennas at the Owens Valley Radio Observatory in California.
The Milky Way shines over the NRL RSD-developed Low Band Antennas at the Owens Valley Radio Observatory in California. (Photo: Courtesy of Gregg Hallinan)

Many of the research institutions collaborating on the LWA project have already adopted NRL’s design, and have additionally used it for other LF receptor needs. NRL’s invention provides an economical solution for antenna arrays that cover many miles.

The LWA project, by using many antenna stations to build a very large aperture, will open a new astronomical window on one of the most poorly explored regions of the electromagnetic spectrum. It is a complement to New Mexico’s existing Very Large Array (VLA). The LWA will include many stations, each formed of an array of 256 Economical LF Active Antennas, to span a total aperture of 13,000 antennas. Ultimately, the LWA will be expanded to a larger collecting area (approaching 1 sq km at its lowest frequencies) and spread over an interferometric array with baselines up to at least 400 km.

The LF regions of the electromagnetic spectrum are of the least studied, due to interference from man-made signals (such as TV and FM radio) and a region of charged particles in the ionosphere; and that a telescope has to be many miles in size to be accurate at a high resolution. As a result, scientists have a poor understanding of the energetics and properties of many cosmic objects and events, the sun, and the ionosphere.

Front End Electronics (FEE) or Active Balun for the Low-Frequency Antenna
Front End Electronics (FEE) or Active Balun for the Low-Frequency Antenna

The core of the LWA will be located near the existing Very Large Array (VLA), but it will encompass interferometer stations spread throughout and possibly beyond the state of New Mexico. The Southwest Consortium (SWC) leads the LWA project. The University of New Mexico heads the SWC; the University of Texas Applied Research Laboratory, the Los Alamos National Laboratory, and NRL are also members.

Click here to see a PDF version of this technology.

Licensing
US Filed Patent Application is available for License to companies with commercial interest. Collaborative research and development is available under a Cooperative Research and Development Agreement (CRADA).

Lead Inventor
Brian Hicks, Electronics Engineer, U.S. Naval Research Laboratory Radio, Infrared, and Optical Sensors (7210)

Patent
US Patent Application No. 14/072715 entitled “Wide-Band Active Antenna System” filed on 11/05/2013 on behalf of Hicks, Brian C; Stewart, Kenneth P; Clarke, Tracy; Dalal, Nagini P; Schmitt, Henrique; Ray, Paul S; Burns, Stephen J, Kassim, Namir E; Polisensky, Emil J

Formal drawing of full polarization, crossed dipole antenna element
Formal drawing of full polarization, crossed dipole antenna element

Publications
"A wide-band, active antenna system for long wavelength radio astronomy",
Brian C. Hicks, Nagini Paravastu-Dalal, Kenneth P. Stewart, William C. Erickson, Paul S. Ray, Namir E. Kassim, Steve Burns, Tracy Clarke, Henrique Schmitt, Joe Craig, Jake Hartman, Kurt W. Weiler.; Astronomical Society of the Pacific, 920; 1090-1104, Published 2012.

Find Out More


Technology Tags: 

Photo Gallery

Click the image to see the slideshow.

The Milky Way shines over the NRL RSD-developed Low Band Antennas at the Owens Valley Radio Observatory in California.
Formal drawing of full polarization, crossed dipole antenna element
The NRL RSD-developed Low Band Antennas deployed at the first Long Wavelength Array station (LWA-1)
Front End Electronics (FEE) or Active Balun for the Low-Frequency Antenna
The First Station of the Long Wavelength Array Radio Telescope Located  adjacent to the Very Large Array on the Plains of San Agustin, New Mexico consists of 256 NRL developed low-band antennas.
The NRL low-band antenna is optimized for ease of assembly without the need for specialized knowledge.  It is shown here being assembled by students.
The NRL low-band antenna provides a consistent beam pattern across the entire range of operating frequencies.
Economical Low Frequency (LF) Active Antenna