METER SSB YAGI PLANS FOR SIDEBAND FUN
This 6 element beam was designed using the
Yagi Antenna Design program by WA7RAI called Quick Yagi
It was designed and optimized using 144.250mhz as the center
frequency which is in the middle of the SSB portion of the 2 meter band
and according to the program has a gain of 11.68dBi with a front to back
(F/B) ratio of 37.44dB on a boom length of 8.68 feet with 1/4 inch
elements using a standard direct feed dipole
insulated from the boom as the driven element with a 3dB beamwidth of
aprox 48.7 degrees..
No matching device should be required but due to
variations in your construction practices, some trimming of driven element
may be needed or us a gamma match with non-split (not insulated from boom)
solid dipole driven element for best SWR.
When checking SWR, place
antenna with reflector on the ground and prop yagi straight up at a ninety
degree angle to earth....use low power to check SRW.....adjust match or
trim as required and recheck. Repeat procedure until lowest SWR is
obtained and mount yagi on your mast, pole, tower, etc in a horizontal
position relative to the ground for 2 meter SSB operation. The SWR in the
final operating position may vary slightly but not enough to worry
The measurements on the picture below may be very hard to obtain
perfectly, but don't worry too much about them! Try to get them as close
as possible using whatever construction practices and genius you can find.
Round them off to next highest or lowest number and forget about
best......... but hard to get in the homebrew invironment!
element (dipole) shown in the inset is insulated from the boom which is
metal by the homemade non-conducting bracket which you must fabricate.
Heavy Plexiglass works fine as long as it is thick enough to support the
driven elements (one on each side).
The two halves of the driven
element can be attached to the insulator using muffler type clamps, u
bolts, several large wire ties or what ever your gray matter can come up
with as long as the elements can not move by outside forces and do not
touch the boom after final installation.
The other elements of the
antenna should be installed thru the boom but if this is not possible for
you, just mount them at the required spacing using your genius. The final
pattern may be slightly off center from the boom by a degree or two but us
it anyway. The idea is to have FUN and experiment!
The conductors from
the feedline (50 ohm coax) are attached as you would any dipole. Center to
one side, shield to the other using whatever arrangement of nuts and bolts
you may have. Seal all connections, coax end and antenna elements from
If you decide to use a gamma match instead of this type
of mounting arrangement for the dipole, you won't have to worry about the
mounting bracket for the dipole but then you will have to decide on a way
to mount the gamma match.
You can design your own gamma match for this
antenna by using a separate program that comes with the Quick Yagi antenna
design software. Get the free complete
This project was designed to
give you a starting point in getting on the air on 2 meter SSB fun with a
respectible signal using just a stock radio and it should increase your
effective radiated power near 9 or10 times (plus or minus a few % for
EXPERIMENT! EXPERIMENT! EXPERIMENT!
editor once built a 6 element yagi for the middle of the band using
discarded aluminum sections for the elements that were "U" shapped from
old junk flouresant light fixtures and attached them to a 1 inch square
boom, 16 inches apart for each and the standard dipole formula 468/freqmhz
was used for the driven element fed with a homebrew gamma match. 5% was
added for the reflector length and each director was shortened 5% shorter
each, progressing to the end of the boom!
SWR was checked as above and
was less than 2 to1 to start but was lowered a bit, down to about 1.5 to 1
and put up on a 16 foot mast with rotor and it worked