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<P style="FONT-FAMILY: ; TEXT-DECORATION: " class=std_10
align=justify><FONT face=Arial><FONT style="FONT-SIZE: 10pt">Making a
simple antenna for 40 Meters is not very difficult. That is, if you have
the space. A standard center fed dipole dipole for 40 Meters needs around
67 Feet of space. But, what if you only have space for a 20 Meter dipole,
33 Feet? If this is case, than you have several options.</FONT></FONT></P>
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<P style="FONT-FAMILY: ; TEXT-DECORATION: " class=std_10
align=justify><FONT face=Arial><FONT style="FONT-SIZE: 10pt">You could
just forget about 40 Meters and work the higher frequency bands, 20
Meters on up.</FONT></FONT></P>
<P style="FONT-FAMILY: ; TEXT-DECORATION: " class=std_10
align=justify><FONT face=Arial><FONT style="FONT-SIZE: 10pt">What? And
miss out on all the fun dodging the the short wave broadcasters in the
evening.</FONT></FONT></P>
<LI style="FONT-FAMILY: ; TEXT-DECORATION: " class=std_10>
<P style="FONT-FAMILY: ; TEXT-DECORATION: " class=std_10
align=justify><FONT face=Arial><FONT style="FONT-SIZE: 10pt">You could
create a Inverted-V type of antenna and raise the feedpoint on a
mast.</FONT></FONT></P>
<P style="FONT-FAMILY: ; TEXT-DECORATION: " class=std_10
align=justify><FONT face=Arial><FONT style="FONT-SIZE: 10pt">This is a
possible alternative, but for this particular case, you would need a 28
Foot center mast and the apex angle would be less than optimum. This may
cause some signal cancelation and give you a radiation pattern that you
don't want.</FONT></FONT></P>
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<P style="FONT-FAMILY: ; TEXT-DECORATION: " class=std_10
align=justify><FONT face=Arial><FONT style="FONT-SIZE: 10pt">You could
shorten the dipole arms to fit the space and use a loading/matching coil
in the center.</FONT></FONT></P></LI></OL>
<P style="FONT-FAMILY: ; TEXT-DECORATION: " class=std_10
align=justify><FONT face=Arial><FONT style="FONT-SIZE: 10pt">Item number 3
is what this page is about. Jact Sobel, W5VM (which is now assigned to
Vernon Dyer), had at one time described a shortened dipole center fed with
a loading/matching coil at the feed point. A drawing of which is
below.</FONT></FONT></P></TD>
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<P style="FONT-FAMILY: ; TEXT-DECORATION: " class=std_10
align=justify><FONT face=Arial><FONT style="FONT-SIZE: 10pt">Initially,
this seems to be a different approach than the shortened dipole designs,
detailed on my<SPAN
class=Apple-converted-space> </SPAN></FONT></FONT><FONT
style="FONT-SIZE: 10pt"><A style="COLOR: ; TEXT-DECORATION: "
href="http://www.k7mem.com/Electronic_Notebook/antennas/shortant.html#Page_Top"><B><FONT
color=#0000ff face=Arial>Short Dipole</FONT></B></A></FONT><FONT
face=Arial><FONT style="FONT-SIZE: 10pt"><SPAN
class=Apple-converted-space> </SPAN>page. But it's really not. If you
tilt your head, and cross your eyes a little bit, you might start seeing
it as two coils, very close together. In fact, the coils are so close to
the center, that they touch..</FONT></FONT></P>
<P style="FONT-FAMILY: ; TEXT-DECORATION: " class=std_10
align=justify><FONT face=Arial><FONT style="FONT-SIZE: 10pt">Assuming that
the two coils are an equal number of turns, and that the wires attached to
each side are equal in length, the center of an antenna should be a zero
current point. this makes a handy place to tie your coax shield. You could
wrap several turns of wire around the coil in the center and feed it that
way. But I couldn't begin to tell you how many turns to use or what the
feed impedance would be. Each turn of the coil, as you move away from
center, provides you with a different impedance and a possible match. By
attaching the center of your coax to one of the coils turns, you should be
able to find a good 50 Ohm feed point. This then gets around the balanced
to unbalanced conversion effort (balun), that would be required and you
were center feeding or link feeding..</FONT></FONT></P>
<P style="FONT-FAMILY: ; TEXT-DECORATION: " class=std_10
align=justify><FONT face=Arial><FONT style="FONT-SIZE: 10pt">Each element
arm is<SPAN class=Apple-converted-space> </SPAN><B>18 Feet 6 Inches
(5.638 M)</B><SPAN class=Apple-converted-space> </SPAN>long. The
loading/matching coils consists of<SPAN
class=Apple-converted-space> </SPAN><B>30</B><SPAN
class=Apple-converted-space> </SPAN>turns of<SPAN
class=Apple-converted-space> </SPAN><B>12 SWG</B><SPAN
class=Apple-converted-space> </SPAN>enamelled copper wire wound
on<SPAN class=Apple-converted-space> </SPAN><B>2.5 inch (63.5
mm)</B><SPAN class=Apple-converted-space> </SPAN>diameter PVC
tube<SPAN class=Apple-converted-space> </SPAN><B>6 inches (152.4
mm)</B><SPAN class=Apple-converted-space> </SPAN>long. The winding
pitch should be about<SPAN class=Apple-converted-space> </SPAN><B>6
turns-per-inch (25.4 mm)</B>. Although the picture doesn't show it very
well, the shield of the 50 coaxial cable is connected to the center of the
coil. The coax center conductor is connected to a point 2 or 3 turns away
from the center, to a point which gives the lowest SWR. This point may
take some experimenting, depending on which section of the band you wish
to operate in.</FONT></FONT></P></TD></TR>
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<DIV style="FONT-FAMILY: 'Calibri'; COLOR: #000000; FONT-SIZE: 12pt"><A
title=http://www.k7mem.com/Electronic_Notebook/antennas/shorty_40.html
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<DIV style="FONT-FAMILY: 'Calibri'; COLOR: #000000; FONT-SIZE: 12pt">73's de
Carlos CT1GFQ<BR>SKCC#466<BR>REP#1406</DIV></DIV></DIV></BODY></HTML>