[Antennas] tune a wire antenna.

Fri, 29 Aug 2003 09:59:19 -0600

My best advice is to invest in an Antenna Handbook.  You can get one at
your local ham store, by mail from HRO or AES or direct from the ARRL
through their web site www.arrl.org .
But for now all you have to do is use the formula for a 1/2 wavelength of
wire (468/f in MHz).  Divide the wire into 2 haves and connect one half
to the coax braid of any 50 ohm coax and the other half to the center
conductor.  Join them in the center with anything you can come up with
that will form a good insulator.  Many hams male their own using a piece
of Plexiglas cut into the shape of a T.  Mount the center as high in the
air as you can and string the ends out flat if you can.  If not you can
let them drop down in to the shape of an "Inverted V" antenna.  An
antenna tuner will allow you to tune a larger segment of frequencies in
the area of your "cut freq." or quite often even several bands if your
cut frequency is for one of the low bands, 40 or 80 Mtrs. for example. 
However don't expect a dipole cut for 10 Mtrs to work well on 80 Mtrs.  
Don't try to make it complicated, to tune a wire antenna to a specific
freq. you only need to cut it to the length by using the formulas you
will find in any of the Amateur Radio Handbooks or the Antenna Handbooks.
 There those who will recommend using the same method as described above
but feeding the antenna with ladder line and tuning it with an antenna
tuner.  I will agree that this method is probably better, and is actually
what I do at my shack for 80 Mtrs.  However the simple way first
described works and will get you on the air and working DX from all over
the world.  Have fun, Get information from books, Learn from other Hams
and work your way up to that 100 ft high tower with a rotator and a 60
ft. long boom on your "Ultimate Beam Antenna"  (If there really is such
an animal, Hi! Hi!!)
73 de Jerry, K�EJF

On Thu, 28 Aug 2003 17:58:57 -0600 (MDT) Nicholas Janzen <[email protected]>
writes:
> I am a fairly new ham, and am really enjoying the hobby so far, I do
> however have a question.
> 
> I would like to know how to tune a wire antenna to match up with a
> specific band/frequency.
> 
> From what i understand this is done using capacitance, so if I had 
> a
> 
> x length antenna in cm
> y frequency in Hz
> 
> what would my capacitance need to be in order to match up with a 50 
> Ohm
> transmitter?
> 
> thanks for any help offered,
> 
> 
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73 de Jerry, K�EJF

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