On Wed, 07 Jul 2004 19:16:36 -0400, Albert wrote:

|OK, thanks Richard.
|
|How about this.
|
|30 wavelengths per side, average conducting ground, 12 feet above
|ground.
|
|What angle do I need for best forward gain, what will the takeoff
|angle be at that angle?

Included angle from 12 to 16 degrees will give ~20 dBi at 6 deg
elevation.
|
|If I can get the entire antenna up to 20 feet above ground, how much
|better is the performance?

~ 2 dB more gain at 4 deg el.
|
|Is there any way for me to do modelling myself without burdening you
|or someone with a modeling program? I am not aware of free software
|that will model rhombics or vee's.

4nec2 is free, do a Google search

Multinec is cheap and very flexible.

|
|Thanks,
|
|Art
|
|ky1k at pivot dot net
|
|PS: Some additional info. This is for EME, which does not require much
|movement. Since it is so long, it won't be variable in the elevation
|angle anyway. But, I hope to move one wire a bit so I can steer the
|beam to the left or to the right a little (changing the angle of the
|vee at the same time).

Since I worked VK5MC to complete my 2-meter WAC and he used a slightly
steerable rhombic, I'm not going to say that this won't work, but I
must question why. If you're going to limit yourself to a few minutes
of moon time a month, why not just put up a long fixed Yagi and use it
for both transmit and receive. A forty-foot long Yagi will give the
same gain as the vee, with a *huge* improvement in the pattern and it
will have a much more tractable feedpoint impedance.

Wes