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Antennas don't have to be sized to the wavelength of the signal. It just happens, that if they are significantly smaller than a quarter wavelength, the sensitivity drops very quickly with antenna size. That, by the way, is also an enormous advantage for electronics design of switched mode power supplies. If the transmission efficiency wouldn't drop, our ...


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Antennas don't have to be sized to the wavelength of the signal. It just happens, that if they are significantly smaller than a quarter wavelength, the sensitivity drops very quickly with antenna size. That, by the way, is also an enormous advantage for electronics design of switched mode power supplies. If the transmission efficiency wouldn't drop, our ...


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It doesn't really matter if you're talking about transmission or reception; the answer is basically the same. A quarter-wave antenna for the commercial AM band would be about 80 meters long, which would clearly be impractical for a receiving antenna. The gain is lower because it's not resonant, but that's OK, you just amplify. You can amplify a lot because ...


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The idea behind the quarter wavelength antenna is that it is self-resonant: it is "tuned". You can however use an antenna of any size to pick off some electromagnetic energy - and you can tune the antenna by adding some inductance in series (or inductance and capacitance). The reason that you tune an antenna is simply this: you want it to have real ...


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With a resonant antenna, the reactance (capacitive and inductive) should be zero. Short antennas are usually capacitive so that capacitive reactance is offset using an inductor. Often for an AM radio a loop inductance is included. Also, some antennas are longer than they appear because the conductor is wrapped around the core of the antenna (sometimes you ...



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