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CENTER-FED MONOBAND INVERTED LONG WIRE VEE
Edited from a project by
 Edward M. Noll, W3FQJ
in the book "73 Dipole and Long Wire Antennas"
published by Editors and Engineers, Ltd, Copyright 1969

Edward Noll had many great antenna  projects in his book.
Lots of them were based on the 3/4 wave length per side dipole.
Presented here is one of them!


Antennas can be resonated to a specific frequency by making their overall electrical
length a whole multiple of a half wavelength. There is a rise in gain with each half-wavelength addition. In the case of a horizontal antenna, the antenna becomes more directive with antenna length.
The addition of leg lengths in odd multiples of a half wave-length ensures a low impedance center feed point because each leg of such an antenna is an odd number of quarter waves-lengths long.

This project will enable you to build a monoband long wire inverted vee
with 3/4 wave length sides that will have a bit of gain, (amount not stated in the book), for high band operation and long distance compared to a standard 1/2 wave dipole because of its lower vertical angles of radiation, and added leg length. The longer the leg lengths in odd multiples, the more the gain.
It amounts to a very low cost and effective antenna. It  is also less directional than the horizontal dipole or straight long wire antenna.
On a horizontal 3/2 wavelength  dipole, the antenna presents four major lobes and 2 minor lobes.
The four major lobes are at:
45, 135, 225, 315, degrees
The two minor lobes are at:
90 and 270 degrees
with respect to the horizontal antenna as viewed from above as in line below:

VIEW FROM ABOVE


90


180 Degrees ______________________ 0 Degrees



270





A practical 20 meter basic design, assuming a 25 to 45 foot mast is used can be determined by the formulas below:
(As always, it is wise to cut lengths long and trim as needed for best resonance)


Leg length = 738
divided by frequency in mhz
Leg length each half = 738
/14.2 = 52 feet

Line length = 650
divided by frequency in mhz
Line length = 650/14.2 = 45 feet 9 inches.

The "magic" numbers (
738 and 650
) in the formulas above appear to be arrived at by trial and error by Ed Noll and were presented in a chart in the book.
To arrive at the "magic" numbers (constants) for each formula for different leg lengths and feeder lengths as determined by your particular lot size,  just do the following:

For longer leg lengths add 492 to each odd multiple of a 1/4 wave length:
Example:
3/4 length  = 738
/freq
5/4 length = 1230
/freq
7/4 length = 1722
/freq
and so on

For longer feed line lengths,
(REMEMBER THAT FEED LINE LENGTH MUST BE AN INTEGRAL MULTIPLE OF A HALF WAVE LENGTH TAKING THE VELOCITY FACTOR OF THE LINE INTO CONSIDERATION!)

Example: 1/2  2/2  3/2  4/2  etc
VF .66 LINE   VF .81 LINE
1/2  325/F      
400
/F
2/2  650/F       800
/F
3/2  975/F      1200
/F

Notice that that for .66vf line,
325 is added each time and for .81 line, 400 is added each time for the constants. (There were no other constants for other velocity factors in the articles in the book, however, you can still use the formula....Line length in feet (1/2 wave) = 492 X VF / freqmhz  for determining the electrical half wavelength of a line)
***********

Higher gain figures can be accomplished by bending the legs forward toward the receiving station.
See the
3 Halfwave Vee Beam based on these same principles by Ed Nolls, W3FQJ.

Editor's note:

If you can find a copy of Ed's "73 Dipole and Long-Wire Antennas", by all means, get it.
Ed also wrote many other books related to radio.  Many are out of print but still can be found.
You will have many hours of fun building and experimenting with Ed's designs which are a culmination of his many years of very talented dedication to Amateur Radio......N4UJW



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