"Wave angle is determined by height, ground characteristics,
and polarization of the antenna...."
Tis true, tis true!
I just jumped to a conclusion and assumed that when most people build
this antenna, it would be a low height or maybe like two crossed
inverted vees, supported by one center support. The reason being, it is
difficult to get this antenna very high. Maybe I should not have made
that assumption. If you put this antenna at or above about 80 feet, it
does have decent low angle performance, but this requires four or five
80 ft supports, for a flat top, which most people don't have. If you
slope the ends similar to an inverted vee, you will need a center
support of around 100 ft to be roughly equivalent to the flat top
version. At these heights, the antenna also shows more directivity, but
still no big nulls that a dipole has off the ends, which is due to some
interaction between the elements.
If you go to the trouble of putting this antenna at 80 ft and want low
SWR, you will probably also want a matching network because Z now looks
closer to 75 ohms. If you use 75 ohm cable you should be able to get SWR
under 1.5 to 1 across the entire 80 meter band. Then again, if you are
able to get an antenna at this height, Cebik's method of matching,
mentioned earlier, becomes possible, and you may be able to acomplish
broadband matching with only a dipole. It is also easier to put a
dipole at this height than it is to put crossed dipoles at this height.
Tom Rauch wrote:
>Wave angle is determined by height, ground characteristics,
>and polarization of the antenna.
>Bowtie or not, pattern shape is not significantly different
>than a regular dipole. For all purposes, even picking nits,
>they are the same. That's even true for an "X " dipole where
>the X acts essentially like a regular dipole with legs
>centered between active wires.
>An essentially "omni" pattern (not truly omni, but close)
>occurs only when an X dipole has elements fed with
>quadrature phase. In other words the two crossed dipole
>elements have to be fed someplace near 90 degrees
>Even that doesn't make it a cloud warmer, height and ground
>characteristics set the elevation pattern.
>See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless
>Weather Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any
>questions and ask for Sherman, W2FLA.
>TowerTalk mailing list
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather
Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions
and ask for Sherman, W2FLA.
TowerTalk mailing list