I still have my training wheels on, but I am trying to model the subject
antenna, as described in the ARRL's Antenna Classics.

The feed end at ground level calls for a 9:1 transformer. The opposite end
(also at ground level)calls for a 9:1 transformer with a 50 ohm dummy load
attached. How would I include these in the model?

Thanks for your patience and help.

Bill

On Mon, 28 Feb 2005 08:34:30 -0500, "William M. Bickley"
wrote:

I still have my training wheels on, but I am trying to model the subject
antenna, as described in the ARRL's Antenna Classics.

The feed end at ground level calls for a 9:1 transformer. The opposite end
(also at ground level)calls for a 9:1 transformer with a 50 ohm dummy load
attached. How would I include these in the model?

I would include a one-segment wire at each end to hold the source and
load. Use a 450 ohm load and set the alternate SWR Z to 450 if you
want to see the SWR normalized to that value.

This assumes that the 9:1 transformers don't add any reactive effects,
something you can't know anyway without some measurement
characterization.

For anyone who's curious, the antenna is described as follows:
The tilted half-rhombic antenna resembles the more familiar "sloping V"
antenna. The difference is that the tilted half rhombic is fed at an end,
and a sloping V is fed at the center (apex). The feedpoint and terminating
point of the antenna are placed on diagonally opposite corners of the given
area. To keep the supporting structure from being an obstruction, it is
located in one of the remaining corners.

From a bird's eye view, the footprint of the antenna is a letter "L", with
the apex at the junction of the two legs. The antenna has 27.2 meters of
wire in each leg. The included angle formed by the two legs is 95 degrees.
The height at the apex is 9.5 meters. A 9:1 transformer is located at the
feed end. A 9:1 transformer is attached at the terminating end, to which is
attached a 50 ohm dummy load. a counterpoise wire runs between the two
transformers, and runs "along or just a few inches below ground."

The gain and SWR numbers included in the article (using AO) a

Freq Gain (dBi) SWR

28.0 7.5 1.94

24.9 7.1 1.72

21.0 7.0 1.46

18.1 6.0 1.26

14.0 4.0 1.60

10.1 1.7 1.34



Bill

"Wes Stewart" wrote in message
...
On Mon, 28 Feb 2005 08:34:30 -0500, "William M. Bickley"
wrote:

I still have my training wheels on, but I am trying to model the subject
antenna, as described in the ARRL's Antenna Classics.

The feed end at ground level calls for a 9:1 transformer. The opposite
end
(also at ground level)calls for a 9:1 transformer with a 50 ohm dummy
load
attached. How would I include these in the model?

I would include a one-segment wire at each end to hold the source and
load. Use a 450 ohm load and set the alternate SWR Z to 450 if you
want to see the SWR normalized to that value.

This assumes that the 9:1 transformers don't add any reactive effects,
something you can't know anyway without some measurement
characterization.

On Mon, 28 Feb 2005 18:17:54 -0500, "William M. Bickley"
wrote:

Freq Gain (dBi) SWR

28.0 7.5 1.94

24.9 7.1 1.72

21.0 7.0 1.46

18.1 6.0 1.26

14.0 4.0 1.60

10.1 1.7 1.34



Bill


how much, if any, loss would there be to that gain due to SWR?


--
73 for now
Buck
N4PGW