Subject: J-POLE ANT
                
J-POLE construction.


                A _       
                   |       
                   |         A-B 5/8 Wavelength
                   |
                   |         Length (Meters) = (187.5)/Freq (MHZ)
                   |
                   |      
                B _|    _D 
                   |   |  
                   |   |     C-D 1/4 Wavelength
                   |   |
                   |   |     Length (meters) = (75)/Freq (MHZ)
                C _|___|_C' 
                   |
          Mounting |
          stub     |
          any      |
          length   |

   Example for a freq. of 145.25 mhz.  A-B = (187.5)/145.25 = 1.29M=129cm
                                       B-C =(75)/145.25 = 0.516M =51.6cm
                        total length   A-C = 180.6cm  (A-B)+(B-C)

   Construction.  The best construction is to use 1/2 in. copper water pipe.
   You can obtain 10'length at any hardware store. One 10' length
   will make a 2 meter ant with a mounting stub.
   You will also need  2 ea. 1/2" end caps.   at A and D
                       1 ea. 1/2" Tee.       at B
                       1 ea. 1/2" st. ell.   at C'

 Connecting  coax
                   Make a square loop 4 cm wide and 8 cm high of
       ___   _     #12 or #14 plastic insulated electrical wire.
      |   |
      |   |        make the distance x to y the same as the spacing
      |   |        between the center and shield of the coax.
    c | __|c'_     solder the connections to a length of coax. I use 
      | |          RG8/U as it is easier to make the connections.
      x y          Tape the connections with a good grade of insulating
                   tape.  this link you have made can now be placed 
                   at points c and c'.  With a SWR meter move the link
                   up and down until you can get as close to 1:1 as 
                   possible. then tape the link to the stub with good
                   tape or you may use cable ties to hold it in
                   place.  With a minimum cost you have a good vhf antenna.

I have two j-pole up for about 5 years and they work fine.
If you want to build a j-pole for 220 mhz and 440 mhz a ten foot section
will be more than needed for both antennas.  If you want to try 6 meters
I would use 3/4" or 1"  copper pipe.
If metric is confusing to you, when you are at the hardware store purchase 
a tapr measure with ENGLISH AND METRIC scales and no conversion needed.