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#1
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I think when an antenna has the wrong size it helps to connect
the antenna to the ground and this helps to make the size right - I think the ground helps to this more flexible I guess when an antenna is small a lot of charge can get around 1 end and can be bad I do not know why a big antenna would have a lot of trouble people talk about adding capacitors and coils to an antenna to decrease resistance when it has the wrong size - I would like to know how a coil would change length like a coil may change speed of electrons as they move toward 1 end thank you for any answers Kurt Stocklmeir -- --- Posted from http://lu7abf.org.ar/news --- news://freenews.netfront.net/ - complaints: --- |
#2
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In article ,
kurt stocklmeir wrote: I think when an antenna has the wrong size it helps to connect the antenna to the ground and this helps to make the size right - I think the ground helps to this more flexible I guess when an antenna is small a lot of charge can get around 1 end and can be bad I do not know why a big antenna would have a lot of trouble people talk about adding capacitors and coils to an antenna to decrease resistance when it has the wrong size - I would like to know how a coil would change length like a coil may change speed of electrons as they move toward 1 end thank you for any answers Kurt- One common antenna is a HALF WAVE DIPOLE, fed in the center with two wires. The correct length for a dipole can be determined by dividing the speed of light by frequency of the radio signal, and dividing that by two. Simplified, divide 300 by frequency in MegaHertz to get wavelength in Meters. Divide that by two for length of a half wave dipole. Another common antenna is a vertical QUARTER WAVE GROUND PLANE, fed at the bottom by two wires except one wire is connected to a ground rod or other buried wires. The ground plane wire is half the length of a dipole. What you are asking is more complicated than I can explain here. For example, the best length is actually slightly shorter than the length you would calculate. Adding coils and capacitors do not change antenna length, but make the antenna act as if it were shorter or longer. You need to study things like the differences between resistance, impedance and reactance. Also the wires you connect to the antenna are called a "transmission line", and have their own ideal impedance that must be matched to the antenna. 73, Fred K4DII |
#3
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On Mon, 14 Sep 2015 21:09:57 +0000, kurt stocklmeir wrote:
I think when an antenna has the wrong size it helps to connect the antenna to the ground and this helps to make the size right - I think the ground helps to this more flexible I guess when an antenna is small a lot of charge can get around 1 end and can be bad I do not know why a big antenna would have a lot of trouble people talk about adding capacitors and coils to an antenna to decrease resistance when it has the wrong size - I would like to know how a coil would change length like a coil may change speed of electrons as they move toward 1 end thank you for any answers Kurt Stocklmeir From the way your post is worded, it sounds like you have been reading web sites put up by various kooks who say they are experts but really don't know anything. Get a good antenna theory book from ARRL or some other good source. That will clear up a lot of your confusion. -- Jim Mueller To get my real email address, replace wrongname with dadoheadman. Then replace nospam with fastmail. Lastly, replace com with us. |
#4
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Jim Mueller wrote:
On Mon, 14 Sep 2015 21:09:57 +0000, kurt stocklmeir wrote: I think when an antenna has the wrong size it helps to connect the antenna to the ground and this helps to make the size right - I think the ground helps to this more flexible I guess when an antenna is small a lot of charge can get around 1 end and can be bad I do not know why a big antenna would have a lot of trouble people talk about adding capacitors and coils to an antenna to decrease resistance when it has the wrong size - I would like to know how a coil would change length like a coil may change speed of electrons as they move toward 1 end thank you for any answers Kurt Stocklmeir From the way your post is worded, it sounds like you have been reading web sites put up by various kooks who say they are experts but really don't know anything. Gareth Alun Evans G4SDW has a website? -- STC // M0TEY // twitter.com/ukradioamateur |
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