>Seems like if you tilt the beam upward, the takeoff angle would
> be increased accordingly, so if you were shooting over the top of a
> station, state, or country you wanted to work, you could just increase
> the takeoff angle until you reduce the radius of the skip to place your
> signal right where you wanted it. Why didn't someone think of this a
> long time ago?!?
Because what controls the far field apparent "take off" angle
is the height of the antenna above ground, and the ground
conductivity out in the so called "fresnel zone". And this
only works when the ground appears "flat" to the energy
between the tower and out to the end of the near field
area.
Of these three "controls", none
are changed by the "tilt" of the beam boom. In fact, doing
so will just skew the pattern that is trying to establish a
desirable take off angle.
Firing into a hillside may get some energy over the hill,
but it is going to be by diffraction, etc.
73, Jim, KH7M
--
FAQ on WWW: http://www.contesting.com/towertalkfaq.html
Submissions: towertalk@contesting.com
Administrative requests: towertalk-REQUEST@contesting.com
Problems: owner-towertalk@contesting.com
Search: http://www.contesting.com/km9p/search.htm
|