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I knew I wanted one for the 20 meter band.  Look closely for the wires going to the top on each side. This is how I did it
and you can too.
Using the
formula from the "Hentenna Revisited
Project" on
Hamuniverse.com,
(refer to it if needed). I came up with the following: I used 14.300Mhz as the design frequency. 15744/14.300 Mhz which
gave me 1100.9 inches or 91.74 feet total wire for the
rectangle.
5904/14.300 Mhz =
412.86 inches or 34.40 feet for the sides.
1968/14.300 Mhz =
137.62 inches or 11.46 feet for the top and bottom.
1180/14.300 Mhz =
82.51 inches or 6.87 feet for the feedpoint.
Note: As the feedpont
varies with the material used (#14 AWG stranded, insulated wire) you may
need to move the feedpoint up or down to resonance. The feedpoint will be
between 1/6 and 1/10 wavelength. With this wire the feedpoint has
been closer to the 1/6th WL so I used this formula: 1005/14.3/ 1/6
which gave me 11.8 feet for the feed point on each
side.
I cut 92 feet of wire
to allow for the solder joint, joined the pvc so that I had 2 ea 11
1/2 ft. pieces for the top and bottom, fed the wire through the
pvc and soldered it. This automatically gave me 34 1/2 foot sides
when hanging. Neat, huh?
I also added a "dirty balun" consisting of 8 turns of coax wound on a 2 liter bottle seen in the photo below in the red circle.
I pulled the top pvc up through the bough of a tree and stripped 2 feet of insulation from the wire between 10 and 12 feet on each side, attached the coax to the feedpoint wires and moved it to where the swr was below 1.8:1. The Hentenna is very broadbanded so I knew at 1.4:1 say, I would not have any problem with the phone portion of the band. I then hoisted it
up as high as I could (need to get it in a taller tree but have to wait
till the leaves fall or put up the 100 ft. tower). Needless to say the
results were amazing. On the air performance! I worked more stations from Brazil to So Cal and of course more TX, AZ, and most said they thought I was pushing my "amp" pretty hard (I was running 50 watts and had the mic gain at 50%!). I turned the mic back to 20% and it is a hand mic! That made them happy, HI HI! I worked every station I tried on no more than the 2nd call. There was the Texas county contest going on and as AD5WB said from Galveston "You got a BIG signal in here." I am guessing that the 1 1/3 wavelength helps as it is using a full wave on frequency with 1/3 wave to match. The Hentenna has
outperformed any dipole or loop I have ever built.
73 de N5NNS George
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