An International agreement says no ones permitted to transmit radio frequencies at around 1420 mgahertz. Why?
952560
That frequency is interesting for radio astronomy and astronomers don't want artificial signals interfering with their observations. However I had not heard of an international agreement not to use that frequency.
79854
YOU HAVE TO BE WITHIN A CERTAIN RANGE OF A CELL TOWER. IF YOU ARE TOO MANY MILES AWAY, YOU WILL NOT HAVE A SIGNAL.  MANY PEOPLE THAT LIVE OUT IN THE COUNTRY CAN'T EVEN USE CELL PHONES/
1061136
Simply because microwave radiations impart energy to atoms and molecules in the crystal structure. Materials which can withstand the induced extra energy are safe, others are not.
25439
There is some sort of a polymer that blocks 4 Ghz, which is WiFi, and yet allows other frequencies through. \nhttp://www.forcefieldwireless.com/windowshield.html\n\nHere is a company that makes glass that will block cell phone signal frequencies. They also sell the polymenrs with various blocking capacity. \nhttp://www.lessemf.com/plastic.html\n\nNice question. I won't have to smuggle that cell phone jammer back from Europe after all!!!
1098693
Of course.  The 75Mhz device uses a transmitter and receiver operating at the same frequency through the use of crystals.  You would have to change the crystals in both the transmitter and the receiver for it to work.  Kind of like a police band radio which has multiple crystals set to certain frequencies.  You can also purchase adjustable crystals to set your own.
806409
If they go to an 800Mhz digital system, you're pretty much out of luck unless you want to spend a lot of money for a digital scanner. I have the same problem.
1140798
go to: radioisla1320.com\nclick to hear live
237400
An channel in communications will allow a certain range of frequencies to pass through it without attenuating (removing) it too much. In band pass communications this is a range of frequencies in the electromagnetic spectrum (eg. 400MHz-500MHz is a possible wireless frequency. In baseband communication the range is between 0 and a certain value and this is not normally suitable for wireless communications carriers.
1044769
They are compatible.  One of the specifications of the 802.11g standard is that it must be compatible with 802.11b.  There may be settings which disable 802.11b mode.  Look for those if you are having trouble.  However it is very likely that they will work with each other out of the box.\n\nEdit:\nStoner is dead wrong.  Lay off the wacky weed!
1186204
The frequency of 50 Hz is to low to modulate with digital, it can be done but would then be ULF.  You can use the 50 Hz transmission line as a digital line as long as the digital stream is not at a freq which is a multiple of the 50Hz then it can filtered out to leave only the digital information. This is a very basic answer Do Not play around with these voltages unless you know what you are doing. High Voltage can seriously damage your health, and equipment.
1060195
You seem to looking for very precice and specific information where the slightest misunderstanding in communication could be an expensive and time consuming mistake. As this is your first antenna built, much of the experience has been played by ear i'm sure, asking advice in places like this.\n\nAbout an hour ago, my sister asked what I'm doing and I said I'm answering questions. As a scientist, she caught on to the fact that anyone could say anything, regardless of the accuracy of the advice, and be trusted. \n\nGiven that your after accurate specifics, I'd suggest you contact a group or discussion panel that specialises in antennas for radio astronomy, and ask the people that acutally know what they are talking about.
437296
If you already know the regulations then you problably know more than I do about them.  All I know is that you need an FCC license.  You have to get the bandwith from the FCC too, I think.   Obviously you'll want the transmitter's antenna to be as high as possible and due to radiation hazards I don't know if you could get away with putting it on the roof of your house.  The link shows a 25mW transmitter for $250.  It also has a 50W transmitter for $2000.
1053320
As frequency increases the wavelength decreases and the equipment needed to transmit a certain distance doesn't need to be as strong. This allows the same powered transmitter to transmit a longer distance. This is why radio frequencies can travel a long distance but the output of a loudspeaker cannot.\n\nI think that was the answer you were looking for, since attenuation would be device dependant.
1002785
Wireless electricity...Sounds kind of complicated.  If they wanted to do it, they could do it from satellites or something.  But it would have the same stipulations as WiFi, there would be areas that transfer the waves, and then there would be areas that don't, because they are out of limit.  Also, if you ever played SimCity, the Electric Satellites have a small tendency to miss, usually during the dry season in a wooded area...not a pretty site...
574269
John O's answer is pretty good, except that microwave frequencies have a harder time travelling a far distance compared to lower frequencies.  \n\nHowever, a lot of people said that cell phones use satellites, and that's simply wrong.\n\nAnyway, it's not only cell phones that can interfere with instruments, but any electronics.  I've read where a handheld calculator would skew the instruments when the buttons were pushed.  That's why you can't have any electronic device on when the plane is taking off or landing, not just cell phones.  As far as the limits for getting a signal, I don't think it's well known because no one has really tested it.  The towers have been tested and are designed for terrestrial use, and the conditions are much different (besides the lack of objects such as hills, trees, and buildings, there is the excessive speed at which you're moving in an airplane, which would make it very difficult if not impossible for your call to be transfered from one tower to another, which would explain why the pilot above said the calls get dropped quickly).
819635
Gigahertz is used for the frequency of the processor and Gigabytes is used for for the storage of the computer. There is no connection between the two.
451863
No, GHz is bigger than MHz for 1000 times.