On 8/7/2014 8:48 PM, Yan (XV4Y) wrote:
At 10°, the Jungle Job still has 7,4dBi gain, while the Moxon shows a -2,3dBi
loss…
This is just a modified 2 element Yagi. Nothing that will
magically give it good low angle radiation. I modeled
a dipole, ZL special, and 8JK at 10 feet high, 10 degrees
elevation vs the same antennas in free space. All three
were down about 9 dB 10 feet over ground vs free space.
The relative gains of the three antennas over ground were
within a few tenths of a dB compared to their free space
rankings. For the Jungle Job to have 7.4 dBi at 10 feet,
it would need to have 16 dBi in free space. No way.
In fact, it would be a stretch for it to have 7.4 dBi
even in free space.
What we can conclude is that ground gain is a function
of height, not antenna type. If someone has a counter
example, I would love to hear about it.
In any event, a half wave vertical (IE Parz end fed)
will probably beat anything horizontally polarized
at 10 feet high on 20 meters, and the vertical virtually
fits in your pocket. Add a 33 foot telescoping fishing
pole if necessary for support. Very portable.
Rick N6RK
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