energy transfer is a big deal these days. This video from Intel labs shows an Intel engineer demonstrating his
setup for transferring energy from a primary coil to a secondary coil located a couple feet away. The fundamentals
aren't rocket science; this is basically a loosely coupled transformer that relies on mutual coupling of magnetic
fields to move power from one place to the other. The trick is making the system highly efficient with small coil
sizes. Consider the challenge of merely transferring low power data via near field communications (NFC)
with coils the size of a cell phone cover.
Texas Instruments and other companies are rushing to provide development platforms for contactless charging
systems that are expected to eventually replace the wall wart world of chargers.
Increasing use of wireless communications require more and more antennas to
support their data transmission. Many situations have limited available real estate for antenna placement. For
example, Navy ships normally use metallic antenna elements to transmit and receive VHF (Very High Frequency)
signals. However, these protruding structures lead to sighting problems and take up valuable space onboard.
Additionally, the height of the antennae cause the ships to be detected on radar scans. The typical Navy vessel
currently houses 80 different antennae. With increasing antenna demand in many situations, smaller antennas are
becoming more valuable to save precious surface real estate.
SSC Pacific has developed a technology that uses the magnetic induction properties of sodium chloride (salt)
in sea water to create a VHF antenna. Sea water is pumped from the ocean into a stream and the width and length of
the stream determine the frequency capabilities. An 80-foot-high stream could transmit and receive from 2 to 400
MHz with a relatively small footprint. The Sea Water Antenna is capable of transmitting and receiving VHF signals
and has been tested at a receiving range of over 30 miles. The antennae needs of a typical Navy vessel with 80
metallic antennas could theoretically be replaced with only 10 Sea Water Antennas of varying heights and streams
to cover the same frequencies. The technology could potentially be used on land with salt-supplemented water,
replacing large unsightly antenna towers with fountains. Another use could be as a solar- or battery-powered
emergency antenna system for watercraft.
- System could decrease antenna footprint in situations where shipboard real estate is scarce by eliminating
the need for metallic antenna structures
- The height and width of the water stream could be adjusted to allow the Sea Water Antenna to transmit and
receive many different frequencies
- The Sea Water Antenna could be turned off when not in use, with no unsightly structure obscuring views, or
even allowing ships to avoid radar detection
- System could be used portably as an emergency antenna for watercraft, potentially powered by battery, solar
panel or foot pump
Patent Pending: Navy Case Number 84943: Electrolytic Fluid Antenna
This collection of video and a few audio files represents files that have been featured on the RF Cafe homepage. Every week or so a new file
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Please send me an e-mail if you have a good subject.
Note: "Videos for Engineers" formerly went by the name "Cool Videos."