It is not required to switch between an off and on state you may switch between a lower and higher voltage as well. With the type of transmitter we are making one state will be totally off or 0 volts while the other will be on or the full voltage. The field strength, or amount of RF energy given off, is directly related to the difference in voltage between the two states.
Using multiple antennas will cause the transmissions to be greater on more frequencies. The range for this frequency will be further than others. As a result there will be more RF energy on that frequency, and harmonics or multiples of that frequency. The antenna of this particular device will be more resonant on one frequency than others. The range of this type of jammer is based on a few properties. The clicking is RF energy that is being picked up from the light switch. Flip your room lights on and off in rapid succession, you should hear a clicking from the speakers. Computer speakers that are on will work as will a stereo set to CD or tape with no CD or tape playing. Turn on some speakers so they are powered but nothing is coming out of them. You can test this in your house fairly easily. When this happens electromagnetic radiation is emitted. Send a high voltage current through an air gap, when the resistance of the air breaks down a spark will cross the gap. They operate as jammers for the same reason they were banned, they take up a lot of the radio spectrum.Ī spark gap transmitter is fairly simple. Now the only way to use them legally is inside a faraday cage.
World War II delayed their complete ban outside of emergency communications for a few years. They were first used around 1888 and remained legal until the 1920s when their use became greatly restricted. Spark gap transmitters are the oldest type of radio transmitter made by man.
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