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One way to prevent high voltage at the ends of an antenna is to reduce =
the Q. The easiest way to do this is to use a lossy wire for the =
antenna. This will also reduce the SWR variations as you change =
frequency. =20
Galvanized Iron electric fence wire is cheap and reduces Q nicely. =
Since losses are high, it reduces noise pick up on receive - especially =
from stations a long distance away.=20
For the ultimate in Q reduction, nichrome works very well. With at =
least a quarter wave of nichrome, the end insulators can be made of =
silver and they will not introduce appreciable losses.
Lossy antennas eliminate the need for antenna tuners and eliminate the =
need to calculate 1/4 waves. They also allow you to tune up on the =
actual antenna without having to bother with the dummy load - a real =
boon to contest operators who like to tune up on frequency. =20
For quiet reception, the ultimate antenna is created by removing the =
center conductor from 1/4 wave coax and replacing it with 1/4 wave of =
nichrome. =20
The cubical quad was invented to eliminate corona effect of high power =
antennas. Beams and dipoles in the Andes had the corona effect and kept =
destroying themselves. Apparently the designer did not know about =
nichrome. Instead, he built a quad to eliminate ends of the antenna. =20
Colin K7FM
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<DIV><FONT face=3DArial size=3D2>One way to prevent high voltage at the =
ends of an=20
antenna is to reduce the Q. The easiest way to do this is to use a =
lossy=20
wire for the antenna. This will also reduce the SWR variations as =
you=20
change frequency. </FONT></DIV>
<DIV> </DIV>
<DIV><FONT face=3DArial size=3D2>Galvanized Iron electric fence wire is =
cheap and=20
reduces Q nicely. Since losses are high, it reduces noise pick up =
on=20
receive - especially from stations a long distance away. </FONT></DIV>
<DIV> </DIV>
<DIV><FONT face=3DArial size=3D2>For the ultimate in Q reduction, =
nichrome works=20
very well. With at least a quarter wave of nichrome, the end =
insulators=20
can be made of silver and they will not introduce appreciable=20
losses.</FONT></DIV>
<DIV> </DIV>
<DIV><FONT face=3DArial size=3D2>Lossy antennas eliminate the need for =
antenna=20
tuners and eliminate the need to calculate 1/4 waves. They =
also allow=20
you to tune up on the actual antenna without having to bother with the =
dummy=20
load - a real boon to contest operators who like to tune up on =
frequency. =20
</FONT></DIV>
<DIV> </DIV>
<DIV><FONT face=3DArial size=3D2>For quiet reception, the ultimate =
antenna is=20
created by removing the center conductor from 1/4 wave coax and =
replacing it=20
with 1/4 wave of nichrome. </FONT></DIV>
<DIV> </DIV>
<DIV><FONT face=3DArial size=3D2>The cubical quad was invented to =
eliminate corona=20
effect of high power antennas. Beams and dipoles in the Andes had =
the=20
corona effect and kept destroying themselves. Apparently the =
designer did=20
not know about nichrome. Instead, he built a quad to eliminate =
ends of the=20
antenna. </FONT></DIV>
<DIV> </DIV>
<DIV><FONT face=3DArial size=3D2>Colin =
K7FM</FONT></DIV></BODY></HTML>
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