Roy, thank you so much for taking the time to respond. I am going to go play
with W6ELProp right away.

I am a very happy EZNEC user... this is how I am finding out the elevation
angle of the major lobe, and because it's easy to 'adjust' by varying the
height of the antenna, especially at a Field Day site, I want to put it up
to maximize coverage of the rest of the country.

Thanks again.

Regards,

Al W6LX

P.S. I should probably start a different thread to make this comment, but I
am still trying to find a good analysis program to enable simulation of an
balanced-line end-fed antenna, sometimes called a Zepp. This evidently is
one tough problem to solve.

"Roy Lewallen" wrote in message
...
A number of propagation programs can tell you what angle you need. One
that's easy to use, reasonably accurate, and free is W6ELProp, available
from http://www.qsl.net/w6elprop/.

The ideal height for the antenna is a fairly easy geometry problem, but
it's easiest to let a program tell you this, too. There are a number of
antenna modeling programs available, some of which are free, and all
will give very accurate results. Because it's my product, I recommend
the free demo version of EZNEC from http://eznec.com, which is entirely
adequate for this purpose. But any number of other programs would be
suitable also.

One bit of advice -- don't get hung up on the "takeoff angle" reported
by some antenna analysis programs (like EZNEC). It simply means the
angle at which the pattern is maximum, and isn't important for this or
most situations. What counts is the field strength or gain at the angle
which you'll be using for communication -- that's the angle reported by
the propagation program. That's the number you want to maximize.

Roy Lewallen, W7EL

Al Lorona wrote:
Hi, Everybody,

How does one determine the correct antenna takeoff angle to communicate
over
a certain distance?

I can't find any references anywhere that discuss this, taking into
account
all of the variables: height of ionosphere, frequency, etc.

Here's a practical example of when it would be important to know this.
Say
you are going to put up a dipole antenna for 20 meters specifically to
communicate to a friend 2000 miles away during the day. The takeoff
angle of
the major lobe varies widely as the antenna is raised from ground level
to 1
wavelength above ground, so presumably there is a 'best' height for the
antenna to put the major lobe right where it needs to be to skip to your
friend's QTH.

The trouble is, we do not seem to have a good way to determine this
'best'
height ahead of time. One would, I guess, have to vary the height of the
antenna while the other station monitored your signal strength, and one
would have to do this over several days, weeks, or months to get good,
averaged data. But... isn't there a better way to do this?

Regards,

Al W6LX

I don't know of any program better than EZNEC for this. (Most others are
just as capable.) You have to realize that the feedline is an integral
part of the antenna, so it must of course be part of the model. Because
it radiates, you have can't use the program's transmission line models,
but have to include the feedline as wires. Depending on the length and
orientation of the feedline, there might also be significant current
flowing from the rig to the Earth via whatever path it can take, and
this is also part of the antenna and must be included in the model if
the model is going to predict the antenna performance.

Just becuase we call one part of the radiating system an "antenna",
another a "feedline" and another "ground" doesn't give them magical
properties and prevent them from radiating. All can be part of the
radiating antenna system and, in the case of a Zepp, generally are.

Roy Lewallen, W7EL

Al Lorona wrote:
P.S. I should probably start a different thread to make this comment, but I
am still trying to find a good analysis program to enable simulation of an
balanced-line end-fed antenna, sometimes called a Zepp. This evidently is
one tough problem to solve.