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antenna
Antenna for detecting other civilization
It is a fact that for many years billions of dollars have been spent to try to locate other civilizations, but without a success. The method used was using high frequency radio waves using large antenna dish antennas. These antennas can communicate with very far spaceships, even at a distance of 100 AU. But they are not suitable to make contact with other civilizations because of 2 main reasons: 1. The antenna is very much directional and receives or transmits signal only to a very narrow angle in the sky. A 70 db antenna ha an angle of only 1 part of 10 million of the sky. To detect signal from other civilization using such antenna would not only require that the antenna will be aimed exactly at the transmitting antenna of that civilization, but also that the antenna of that civilization will be aimed exactly at Earth. The chance that this will occur is 100 e12. 2. A large dish antenna used today transmits in a narrow bandwidth of 64 KHz using a carrier frequency of 8 GHz. The ratio between the two frequencies is about 1:100,000. If an antenna from another civilization will transmit at another frequency out of 100,000 options, than we will not receive it. To overcome this I prepared a plan for a different antenna. The antenna I thought of is a simple dipole antenna in space. This antenna transmits and receives to all directions and is not limited to a very narrow frequency. In order to make it very sensitive to signals I thought to make it as long as possible. I found out that the solar storms make noise, and as we distance the sun the frequency of the noise and the power is decreased. At frequency of 50 KHz and 1 AU from the sun the noise is not significant. At 2 AU the frequency is 25 KHz and at 10 AU the frequency we can use is 5 KHz. The first possible antenna I thought of is a dipole, having a length of 3 Kilometers, placed as a satellite to Earth. To make this antenna and to put it in space would not cost much and there are no risks. It will be optimized for a frequency of 50 KHZ, but will also receive frequencies of 20-200 KHz. The effective area of the antenna will be 9 square kilometers. This is 100 times more than the largest antenna array on earth. In order to detect a signal from outer intelligence, there is a need to detect not more than 100 bits of information. The time for this can be for example 1 day or 100,000 second. The bit-rate will be about 0.001 bits per second. The noise level of an amplifier for that antenna is e-21 watt per Hz. The noise level for that need is e-24 watt. The ratio between the communication distance and the transmitted signal in this case is: Distance^2 Wavelength^2 36 ----------------- = ----------------------- = ------ =~ e26 P transmitter P receiver e-24 In the case that the transmitter power is one million watts, the distance is e16 kilometers, or about e8 AU. This is 1000 times more than the closest star to us. If we put the antenna more far from the sun, the temperature drops and than the antenna wire will have lower electrical resistance. We will be able to make it longer without increasing the weight. A 6 Kilometer antenna can be at about 3 AU from the sun and will have the same weight as a 3 Kilometer antenna. If we further increase the distance from the sun, were the temperature is below 77 degrees Kelvin, than we can use superconductors instead of a metal wire. This will dramatically decrease the weight and enable us to use a 100 Kilometer antenna and frequency of 1.5 KHz that will increase the sensitivity by 1000. The effective area of that antenna will be 100,000 times the area of the antenna arrays on earth. At that frequency and distance from the Sun there is almost no noise from plasma oscillation. By Gil Teva (1) http://www.femto.de/datasheet/DLPVA100BUNS.pdf (2) http://www.ka9q.net/mpf_budget.html (3) http://farside.ph.utexas.edu/teachin...es/node83.html (formula 1001) (4) http://www-pw.physics.uiowa.edu/plas...y/summary.html (5) http://www.amsuper.com/html/newsEven...793757741.html Telefax: 02-6724273 Email: |
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antenna
"Gil Teva" wrote in sci.astro.seti:
snip It seems your antenna is at least successful in broadcasting multiple messages with the same content. -- CeeBee "I am not a crook" |
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antenna
"Gil Teva" wrote in sci.astro.seti:
snip It seems your antenna is at least successful in broadcasting multiple messages with the same content. -- CeeBee "I am not a crook" |
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antenna
CeeBee wrote:
"Gil Teva" wrote in sci.astro.seti: snip It seems your antenna is at least successful in broadcasting multiple messages with the same content. True... but a bit harsh. To Gil, A _brief_ (non-html) summary first might gain greater interest... Good luck, Martin. -- ---------- Give a man a fish and you have fed him for today. - Martin - Teach him how to fish and he won't bother you for weeks! - 53N 1W - - Anon ---------- |
#5
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CeeBee wrote:
"Gil Teva" wrote in sci.astro.seti: snip It seems your antenna is at least successful in broadcasting multiple messages with the same content. True... but a bit harsh. To Gil, A _brief_ (non-html) summary first might gain greater interest... Good luck, Martin. -- ---------- Give a man a fish and you have fed him for today. - Martin - Teach him how to fish and he won't bother you for weeks! - 53N 1W - - Anon ---------- |
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