A new type of pocket-sized antenna, developed at the Department of Energy’s SLAC National Accelerator Laboratory, could enable mobile communication in situations where conventional radios don’t work, such as under water, through the ground and over very long distances through air.
The device emits very low frequency (VLF) radiation with wavelengths of tens to hundreds of miles. These waves travel long distances beyond the horizon and can penetrate environments that would block radio waves with shorter wavelengths. While today’s most powerful VLF technology requires gigantic emitters, this antenna is only four inches tall, so it could potentially be used for tasks that demand high mobility, including rescue and defense missions.
“Our device is also hundreds of times more efficient and can transmit data faster than previous devices of comparable size,” said SLAC’s Mark Kemp, the project’s principal investigator. “Its performance pushes the limits of what’s technologically possible and puts portable VLF applications, like sending short text messages in challenging situations, within reach.”
The SLAC-led team reported their results today in Nature Communications.
A sizable challenge
In modern telecommunications, radio waves transport information through air for radio broadcasts, radar and navigation systems and other applications. But shorter-wavelength radio waves have their limits: The signal they transmit becomes weak over very long distances, can’t travel through water and is easily blocked by layers of rock.
In contrast, the longer wavelength of VLF radiation allows it to travel hundreds of feet through ground and water and thousands of miles beyond the horizon through air.
However, VLF technology also comes with major challenges. An antenna is most efficient when its size is comparable to the wavelength it emits; VLF’s long wavelength requires enormous antenna arrays that stretch for miles. Smaller VLF transmitters are much less efficient and can weigh hundreds of pounds, limiting their intended use as mobile devices. Another challenge is the low bandwidth of VLF communication, which limits the amount of data it can transmit.
The new antenna was designed with these issues in mind. Its compact size could make it possible to build transmitters that weigh only a few pounds. In tests that sent signals from the transmitter to a receiver 100 feet away, the researchers demonstrated that their device produced VLF radiation 300 times more efficiently than previous compact antennas and transmitted data with almost 100 times greater bandwidth.
“There are many exciting potential applications for the technology,” Kemp said. “Our device is optimized for long-range communication through air, and our research is looking at the fundamental science behind the method to find ways to further enhance its capabilities.”
A mechanical antenna
To generate VLF radiation, the device exploits what is known as the piezoelectric effect, which converts mechanical stress to a buildup of electrical charge.
The researchers used a rod-shaped crystal of a piezoelectric material, lithium niobate, as their antenna. When they applied an oscillating electric voltage to the rod it vibrated, alternately shrinking and expanding, and this mechanical stress triggered an oscillating electric current whose electromagnetic energy then got emitted as VLF radiation.
The electric current stems from electric charges moving up and down the rod. In conventional antennas, these motions are close to the same size as the wavelength of the radiation they produce, and more compact designs typically require tuning units that are larger than the antenna itself. The new approach, on the other hand, “allows us to efficiently excite electromagnetic waves with wavelengths that are much larger than the motions along the crystal and without large tuners, which is why this antenna is so compact,” Kemp said.
The researchers also found a clever way of tweaking the wavelength of the emitted radiation, he said: “We repeatedly switch the wavelength during operation, which allows us to transmit with a large bandwidth. This is key to achieving data transfer rates of more than 100 bits per second – enough to send a simple text.”
Learn and see more: SLAC develops novel compact antenna for communicating where radios fail
The Latest on: VLF radiation
via Google News
The Latest on: VLF radiation
- On 5G And The Fear Of Radiationon May 23, 2022 at 5:00 pm
Some are less obvious, for example the dangers of UV radiation to one’s skin and eyes commonly known, but also heavily underestimated by many until it’s too late. In the US alone, skin cancer ...
- Still Working After All These Years: The Voyager Plasma Wave Subsystemon May 23, 2022 at 5:00 pm
They also devised a series of space radio and plasma wave experiments, in part to explore natural very-low-frequency (VLF ... to learn more about the intense radiation belts known to surround ...
- Hazmat Lessons that Can Be Overlookedon May 16, 2022 at 2:06 am
They might be worried about “ethyl methyl death” or “growing a third arm from radiation.” Of course, these are fallacies, but the concern that they can prompt indicates the fears that ...
- Radiation Detecting Devices and Moreon May 14, 2022 at 8:00 am
What is an example of non-ionizing radiation? UV, visible light, microwave, infrared, radio frequency, and very low frequency are all examples of non-ionizing radiation. In addition, lasers are in ...
- Alternative Energy Sources for the Ablation of Arrhythmiason May 3, 2022 at 5:00 pm
They also were able to demonstrate that the depth of lesions from microwave radiation increases exponentially over time as compared to standard nonirrigated RF energy, which had minimal lesion ...
- Artificial modification of Earth’s radiation belts by ground-based very-low-frequency (VLF) transmitterson April 28, 2022 at 1:04 pm
our understanding of the electron dynamics in Earth’s inner radiation belt and slot region has been significantly advanced, in which the contribution of VLF transmitter emissions is found critical.
- Radio tower group petitions to rezone propertyon April 5, 2022 at 1:05 pm
Roman's letter outlines his experience with radio towers and that the proposed towers would operate at a 'very low frequency' compared to others ... or statement on whether or not radio frequency ...
- Schematic illustration of bifurcating energetic electron belt (tens of keV) caused by VLF transmitters (IMAGE)on March 31, 2022 at 12:50 pm
Caption (a) Electron fluxes before (left side) and after (right side) resonant wave-particle interactions with VLF transmitter waves. (b) Variations of radial energetic electron flux profile from ...
- Emission and absorption of electromagnetic radiationon July 25, 2020 at 9:11 pm
All bodies (objects) emit electromagnetic radiation, no matter what their temperature is. The type of radiation emitted depends on the temperature of the body. Hot bodies emit a continuous range ...
- Electromagnetic waves and radar - CCEAon November 16, 2019 at 2:12 pm
Over-exposure to certain types of electromagnetic radiation can be harmful. The higher the frequency of the radiation, the more energy it carries and the more damage it is likely to cause to the ...
via Bing News