A smart fluorescent antenna for Wi-Fi applications

A charged argon gas in the fluorescent lamp emits Wi-Fi signals. Credit: Faculty of Electrical Engineering, Universiti Teknologi MARA

A new invention uses ionized gas in fluorescent light tubes to transmit Internet wireless frequency signals throughout a building with the aid of already existing electrical wiring.

Due to continuously evolving applications, the electronic communications industry requires high performance and speed efficient systems. However, the physical limitations of microwave devices limits further improvements in current technology. This predicament has led to growing interest in the use of plasma as a conductive element in microwave devices due to their unique and innovative properties, which corresponds with traditional metallic antennas.

Matter exists in four different states: solid, liquid, gas and plasma. Plasma is a type of gas in which the atoms are ionized -- they have both free negatively charged electrons and positively charged ions. These charged particles can be controlled by electromagnetic fields, allowing plasmas to be used as a controllable reactive gas.

This invention employs an ionized gas enclosed in a tube as the conducting element of an antenna. When the gas is electrically charged or ionized to plasma, it becomes conductive and allows radio frequency signals to be transmitted or received. When the gas is not ionized, the antenna element ceases to exit.

The invention features a smart fluorescent antenna with a 3G/3.75G/4G router for Wi-Fi applications. The antenna operates at the 2.4 GHz frequency band, which is suitable for Wi-Fi applications. A commercially available fluorescent tube, measuring 0.61 metres in length by 0.25 metres in diameter, is used as the plasma antenna. The gas inside the tube is a mixture of argon and mercury vapour, in the ratio 9:1. The tube is energized by a 240 V current, provided by a standard AC power supply. A glowing tube indicates that the gas inside the tube has been ionized to plasma and forms a plasma column. In this state, the plasma column becomes highly conductive and can be used as an antenna.

A coupling sleeve is positioned at the lower end of the tube, which is used to connect the plasma tube to the router. The function of the coupling sleeves is to store the electrical charge. When the gas inside the tube is sufficiently ionized into a plasma state, it becomes conductive and allows radio frequency signals to be transmitted or received.

Measurements indicate that the plasma antenna yields a return loss over 10 dB in the 2.23 GHz to 2.58 GHz frequency band. The antenna's ability to operate as either a transmitter or receiver in this particular frequency band was verified through a series of wireless transmission experiments.

The performance of this antenna was measured using the Wi-Fi Received Signal Strength 
Indicator (RSSI) technique. The product was tested for a month in the Universiti Teknologi MARA's High Frequency Antenna Laboratory. Our results show that the signal is stronger and more stable compared to others signals.

One advantage of this product is its low cost. The Wi-Fi signal can be transmitted into other rooms using only one router with a splitter cable. The fluorescent tube has dual functionality, thereby reducing the cost of buying additional antennas. Commercial antennas are made from metal elements while this invention uses plasma element as its source of material. Normal antennas can only transmit and receive radio frequencies, while this product not only can be used for transmitting and receiving radio frequency signals, but as a light emitting device as well.

Source: Universiti Teknologi MARA (UiTM)

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Li-fi protocol allows use of the Internet at the speed of light

Sisoft Company in Mexico has developed a technology that can illuminate a large work space, an auditorium or an office, while providing full mobile internet to every device that comes into the range of the light spectrum. Credit: SISOFT

Sisoft Company in Mexico has developed a technology that can illuminate a large work space, an auditorium or an office, while providing full mobile internet to every device that comes into the range of the light spectrum.

The Mexican group managed to transmit audio, video and Internet across the spectrum of light emitted by LED lamps. This new technology, called Li-Fi or light fidelity, is presented as an alternative to Wi-Fi because it will maximize the original provided speed of the internet to offer safer data transfer and a transfer rate of up to 10 gigabytes per second.

The Li-Fi device circulates data via LEDs that emit an intermittent flicker at a speed imperceptible to the human eye. "As Wi-Fi uses cables to spread our connections, wireless transmission Li-Fi uses LED lamps that emit high brightness light," said Arturo Campos Fentanes, CEO of Sisoft in Mexico.

Another advantage in comparison to Wi-Fi is that there is no way to hack the signal since the internet is transmitted by light, there is no way to "steal it." Furthermore, it can be installed in hospitals areas that use radiation apparatus and generally block or distort internet signal, Campos Fentanes said.

With this new technology expansion through the market is seeked, with lower costs and a service increased by five thousand percent internet speed. Currently in Mexico the highest transfer rate is 200 megabytes per second. Just to get an idea, with Li-Fi you could quickly download an entire HD movie in just 45 seconds.

Also known as visible light communications (VLC), this technology began with an internet speed of two Gigabits per second, but Sisoft along with researchers from the Autonomous Technological Institute of Mexico (ITAM) adapted the system to be multiplied five times.

Campos Fentanes explained that the first experiments were conducted with audio, in which a cable is connected via 3.5 mm audio Jack from a smartphone to a protoboard table to transform the auditory signal in optical waves. That way a special emitter transmits data across the spectrum of light generated by an LED lamp and is captured by a receptor located in a speaker that reproduces sound.

For wireless internet transmission, the mechanics is similar. The station developed by Sisoft of Mexico stands above the router device that distributes the internet signal and a lamp-LED is incorporated to maximize the speed of data transfer. Light will emulate an antenna, but only the electronic apparatus that has the receptor for the "optical audio" signal and is inside the range of the halo of light will have a connection. 

Source: Investigación y Desarrollo

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Physicists suggest new way to detect dark matter

This is associate professor Chris Kouvaris from the University of Southern Denmark. Credit: University of Southern Denmark

For years physicists have been looking for the universe's elusive dark matter, but so far no one has seen any trace of it. Maybe we are looking in the wrong place? Now physicists from University of Southern Denmark propose a new technique to detect dark matter.

The universe consists of atoms and particles -- and a whole lot more that still needs to be detected. We can only speculate about the existence of this unknown matter and energy.

"We know that app. 5 pct. of the universe consists of the known matter we are all made of. 

The rest is unknown. This unknown matter is called dark matter, and we believe that it is all around us, including here on Earth," explains Chris Kouvaris, associate professor at the Centre for Cosmology and Particle Physics Phenomenology (CP3-Origins), Department of Physics, Chemistry and Pharmacy, University of Southern Denmark.

He and his colleague from CP3-Origins, postdoc Ian Shoemaker, now suggest a new way to detect the existence of the elusive dark matter.

Cosmic noise is a problem

Over the last years, physicists have placed detectors in underground sites app. a kilometer or more deep in order to detect dark matter. The idea is that dark matter is easier to detect in deep sites because there is less noise from cosmic or Earth-produced radiation that can potentially cover the dark matter signal. This approach of detecting dark matter makes sense provided that dark matter interacts only a bit with atoms as it goes underground. The scientific term for this is that dark matter is weakly interacting with its surroundings.

"But we don't know if dark matter is that weakly interacting. In principle dark matter particles can lose energy as they travel underground before they hit the detector due to interactions with regular atoms. And in that case they might not have enough energy left to trigger the detector once they arrive there," says Chris Kouvaris.

Signals are good 12 hours a day

In a new research paper, he and Shoemaker study the possibility that dark matter can indeed interact substantially with atoms. They claim that depending on the properties of the dark matter particles, deep placed detectors can be blind because particles might have lost most of their energy before reaching the detector.

"In such a case, it would make more sense to look for dark matter signals on the surface of the Earth or in shallow sites," Kouvaris argues.

Placing a detector in shallow sites or on the surface ensures small energy loss for the dark matter particles but it also means a big increase in the background noise. This was after all the reason why detectors were placed in deep sites in the first place. To overcome this problem Kouvaris and Shoemaker propose -- instead of trying to detect a single collision of a dark matter particle with the detector -- to look for a signal that varies periodically during the day.

Because dark matter particles approach the detector from various directions, as the Earth rotates, the flux of the particles reaching the detector can vary. This causes a signal that will go from maximum to minimum in 12 hours and back to maximum again after another 12 hours.

Such a pattern will make the signals from dark matter stand out clear even though the detectors also pick up cosmic noise.

"The best locations for the observation of such a modulation signal are places in the south hemisphere with latitude around 40 degrees, such as Argentina, Chile and New Zealand" says Chris Kouvaris.

What is dark matter and dark energy?

27 pct. of the universe is believed to consist of dark matter. Dark matter is believed to be the "glue" that holds galaxies together. Nobody knows what dark matter really is.

5 pct. of the universe consists of known matter such as atoms and subatomic particles.
The rest of the universe is believed to consist of dark energy. Dark energy is believed to make the universe expand.

Source: University of Southern Denmark

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New revelations on dark matter and relic neutrinos

Temperature map of the relic radiation (bottom left), and close-ups showing, in relief, the polarisation of light in the 353 GHz channel (the colors correspond to the intensity of the thermal emission from galactic dust. Credit: © ESA - Planck collaboration

The Planck collaboration, which notably includes the CNRS, CEA, CNES and several French universities, has disclosed, at a conference in Ferrara, Italy, the results of four years of observations from the ESA's Planck satellite. The satellite aims to study relic radiation (the most ancient light in the Universe). This light has been measured precisely across the entire sky for the first time, in both intensity and polarisation1, thereby producing the oldest image of the Universe. This primordial light lets us "see" some of the most elusive particles in the Universe: dark matter and relic neutrinos.

Between 2009 and 2013, the Planck satellite observed relic radiation, sometimes called cosmic microwave background (CMB) radiation. Today, with a full analysis of the data, the quality of the map is now such that the imprints left by dark matter and relic neutrinos are clearly visible.

Already in 2013, the map for variations in light intensity was released, showing where matter was in the sky 380,000 years after the Big Bang. Thanks to the measurement of the polarisation of this light (in four of seven frequencies2, for the moment), Planck can now see how this material used to move. Our vision of the primordial Universe has thus become dynamic. This new dimension, and the quality of the data, allows us to test numerous aspects of the standard model of cosmology. In particular, they illuminate the most elusive of particles: dark matter and neutrinos.

New constraints on dark matter The Planck collaboration results now make it possible to rule out an entire class of models of dark matter, in which dark matter-antimatter annihilation3 is important. Annihilation is the process whereby a particle and its antiparticle jointly disappear, followed by a release in energy.

The basic existence of dark matter is becoming firmly established, but the nature of dark matter particles remains unknown. There are numerous hypotheses concerning the physical nature of this matter, and one of today's goals is to whittle down the possibilities, for instance by searching for the effects of this mysterious matter on ordinary matter and light. Observations made by Planck show that it is not necessary to appeal to the existence of strong dark matter-antimatter annihilation to explain the dynamics of the early universe. 

Such events would have produced enough energy to exert an influence on the evolution of the light-matter fluid in the early universe, especially around the time relic radiation was emitted. However, the most recent observations show no hints that this actually took place.

These new results are even more interesting when compared with measurements made by other instruments. The satellites Fermi and Pamela, as well as the AMS-02 experiment aboard the International Space Station, have all observed an excess of cosmic rays, which might be interpreted as a consequence of dark matter annihilation. Given the Planck observations, however, an alternative explanation for these AMS-02 or Fermi measurements-such as radiation from undetected pulsars-has to be considered, if one is to make the reasonable hypothesis that the properties of dark matter particles are stable over time.

Additionally, the Planck collaboration has confirmed that dark matter comprises a bit more than 26% of the Universe today (figure deriving from its 2013 analysis), and has made more accurate maps of the density of matter a few billion years after the Big Bang, thanks to measurements of temperature and B-mode polarisation.

Neutrinos from the earliest instants detected

The new results from the Planck collaboration also inform us about another type of very elusive particle, the neutrino. These "ghost" particles, abundantly produced in our Sun for example, can pass through our planet with almost no interaction, which makes them very difficult to detect. It is therefore not realistic to directly detect the first neutrinos, which were created within the first second after the Big Bang, and which have very little energy. However, for the first time, Planck has unambiguously detected the effect these relic neutrinos have on relic radiation maps.

The relic neutrinos detected by Planck were released about one second after the Big Bang, when the Universe was still opaque to light but already transparent to these particles, which can freely escape from environments that are opaque to photons, such as the Sun's core. 380,000 years later, when relic radiation was released, it bore the imprint of neutrinos because photons had gravitational4 interaction with these particles. Observing the oldest photons thus made it possible to confirm the properties of neutrinos.

Planck observations are consistent with the standard model of particle physics. They essentially exclude the existence of a fourth species of neutrinos5, previously considered a possibility based on the final data from the WMAP satellite, the US predecessor of Planck. Finally, Planck makes it possible to set an upper limit to the sum of the mass of neutrinos, currently established at 0.23 eV (electron-volt)6.

The full data set for the mission, along with associated articles that will be submitted to the journal Astronomy & Astrophysics (A&A), will be available December 22 on the ESA web site. These results are notably derived from measurements made with the High Frequency Instrument (HFI), which was conceived and assembled under the direction of the Institut d'astrophysique spatiale (CNRS/Université Paris-Sud), and utilized, under the direction of the Institut d'astrophysique de Paris (CNRS/UPMC), by different laboratories including those from the CEA, the CNRS and French universities, with funding from CNES and the CNRS.

Notes

1. Polarisation is a property of light on the same level as color or direction of travel. This property is invisible to the human eye, but remains familiar (sunglasses with polarised lenses and cinema 3D glasses, for instance).. A travelling photon is associated with an electrical field (E) and a magnetic field (B), at right angles to each other and to their direction of travel. If the electrical field remains in the same plane, the photon is said to be linearly polarised, as is the case for relic radiation.

2. In all three frequencies of the Low Frequency Instrument (LFI) and in the 353 GHz channel of the High Frequency Instrument (HFI).

3. In some models, dark matter particles are their own anti-particles.

4. According to general relativity, even if photons have no mass, they are sensitive to the gravitational force that bends space-time.

5. According to the standard model of particle physics, there are three species of neutrinos.

6. The electron volt (symbol: eV) is a unit of energy used in particle physics to express mass, since mass-energy equivalence links energy and mass (E=mc2, where c represents the speed of light). The lightest known particle after photons and neutrinos weighs 511 keV, more than 2 million times the sum of the mass of all three neutrinos.

Source: CNRS

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