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Liquid Crystal Antenna





rjraaz
Vehicles like cars, ships and aircraft needs to be in proper and stable contact of earth orbiting satellite to properly works with functions like Global Positioning System, for proper Internet access and for satellite television.

Direction and Orientation of such vehicles changes to those satellites, as they move from one place to another place continuously. So for smooth GPS service "electronically redirect-able phased arrayed antennas" are required.

Such type of antennas are more expensive and have limited speed, by which those can track the vehicle. In this context, researchers in Germany have had great success. According to scientists of Technische Universität Darmstadt doctoral student Onur Hamza Karabey doing a research on the alternatives for low-cost, high-performance antenna.

As alternative material he has chosen liquid crystal antenna.

Onur's current format is composed of four LCD cells. By applying the varying voltage
(power) to each of those cells. Then he amplifies the selected radio signals that are coming from the different directions, since the antenna is not having a moving parts, so it takes milliseconds to align themselves with the same satellite.

Such a five-millimeter antenna on the roof of the car can be created, which can align themselves to satellites automatically. Onur hopes that such antennas can be made at low cost with the help of commercial LCD monitors.
Onur is willing to provide the device at a price of $790 at the end of his research.

Source: http://www.tu-darmstadt.de/vorbeischauen/aktuell/ni_44608.en.jsp
Josso
This is interesting it's a good idea. GPS also relies on astronomically accurate UTC which is being debated at the moment as well.
ocalhoun
rjraaz wrote:
"electronically redirect-able phased arrayed antennas"

These have been around for a while, without the use of liquid crystals.

I once worked on a precision approach radar (PAR) that used one such system. (With 1980's technology).
It had several hundred small transmitter/receivers, all pointed (slightly offset) at a curved reflector. The transmit/receive beam could be precisely aimed by varying the signal strength allowed to each transmitter/receiver... And those changes in allocation were done electronically, with no physical moving parts, allowing the beam to scan back and forth across a section of sky very quickly without any physical movement.
(Really, it was quite annoying. The system governing this behavior would often break, and nobody (and I mean nobody!) could really understand it and fix it, because it was so complex.)

Another version was used in the TPS-75 radar system. It used electronic phased arrays to determine the altitude of an aircraft. Several long horizontal receivers were aligned at set distances back from each other, each one corresponding to a different signal phase. The outgoing beam would be phase aligned, but the returning pulse would hit each receiver at a different phase position. By electronically comparing the strengths of the different phased signals received, it could determine the (approximate) angle of elevation the return came from, since the receivers at that angle would get the strongest return signal. (That angle, combined with the time for the round trip, and a little math, would give the altitude of the detected aircraft.)

Another example of an electronically steerable beam is in any CRT display: The electron gun (a fancy name for an antenna) in the back fires a beam, which is steered by electromagnetic forces (or, in some cases electrostatic forces) at the desired location on the screen. Since the steering forces are electronic, they can be electronically varied, which is why the beam could be scanned across the screen thousands of times per second.
I see no reason why a signal transmitter couldn't be steered in the same way, though it wouldn't work particularly well for receivers.


Now, both of those systems were very large and very power-hungry though, so perhaps by using liquid crystals, they can make ones that are small and energy efficient.
menino
Wow, thanks for the information rjraaz and ocalhoun.
I think tracking and GPS technology are becoming quite mainstream nowadays in the technology industry for information gathering and statistics for traffic information.
Still $790 for that kind of tracking device is a lot, but maybe with certain investments, the device can become cheaper.
At $790 for that kind of device, its probably cheaper to use an iphone with its own gps tracking technology, which has the cpability of tracking your speed as well.
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