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Tune Around! Topics For
Technicians!
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MY 40 METER LAZY "H" ARRAY My primary antenna array for the "southcars net" operation. by NA4L Dave Newman "You can
see I stand behind my philosophy on wire
antennas." "Make them simple then Make them work ! !"
(Lengths are a bit fuzzy in the graphic..email Dave for exact numbers) The LAZY "H" antenna is a general type of antenna that
is in the curtain array family. By placing TWO 1 wavelength dipoles in a
plane that is at right angles to the direction of maximum radiation and
keeping the proper in-phase current condition to each element, you can
achieve a HIGH GAIN bi-directional antenna.
For a near omni-pattern, MY version of the LAZY "H"
array needed TWO identical antennas. (See the diagram at the top of this
page.)
One antenna is broadside North and South and one antenna
is broadside East and West.
These antennas are fed AT THE SAME TIME using equal
lengths of 450 ohm ladder line.
Again, all the feed lines MUST be of equal lengths and
the proper in-phase condition to each element MUST be maintained.
This array has a TOTAL of eight (8) 1/2 wavelength
active elements.
The main feed line to my shack for this array is 450 ohm
ladder line.
I use a Palstar AT4K tuner to match the array.
According to EZNEC this configuration will give
basically an omni-pattern with about 4 to 6 db of antenna gain.
The array is cut to operate at 7.251 Mhz, the SouthCars
Net frequency.
With the feed method I am using, BOTTOM FEED, with one
twist and an electrical 1/2 wavelength phase line, (61.7 feet) of 450 ohm
ladder line this equals 360 or 0 degrees, which keeps the elements
in-phase.
Using this feed method the array can be used ONLY on the 40 meter Ham band. As an added plus, this
array is very quiet.
After experimenting with EZNEC, the height of the lowest
dipole seems to effect the radiation coverage. With the low dipole at only
30 feet and the highest dipole at 90 feet, I am able to hear the "close in
stations" AND ALSO "the distance stations."
This should be a GOOD antenna for Net Control Stations,
because they can receive and transmit nearly 360 degrees at the same
time....with antenna gain!
This array is supported on one 100 foot tower and the
ends are supported by tall oak and pine trees.
NO antenna turning necessary with this
array!
So if you have the room, build one and get on the air in
style! 73 Dave!
For questions email Dave at imna4l AT embarqmail.com (Remove the "AT" and add
@ no
spaces)
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