Anyone out there good at antenna modeling?

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poppafred

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I have been fiddling with my G5RV dipole this week. It seems to be working fine but was just wondering about how it would model out with software.

I started with a close-to-standard G5RV and added extra copper wire to the ends. Right now, the 300 ohm ladder line is 30 ft, the wires are 102' total. I use a 4:1 current balun to feed the ladder line.

I don't have any modeling software and I'm not sharp enough to figure out the freeware that is available.

Any help?
 

mtindor

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I have been fiddling with my G5RV dipole this week. It seems to be working fine but was just wondering about how it would model out with software.

I started with a close-to-standard G5RV and added extra copper wire to the ends. Right now, the 300 ohm ladder line is 30 ft, the wires are 102' total. I use a 4:1 current balun to feed the ladder line.

I don't have any modeling software and I'm not sharp enough to figure out the freeware that is available.

Any help?
Is it an inverted V or a flattop? If a V, what is the height of the apex and the height of hte ends. If a flattop, what is the height of the ends?

Then, exactly what band(s) are you wanting it modeled for? The model will be completely different depending upon the band.

Now, I'm not claiming that I can model it for you. But I can tell you that all of the above need to be known before it can be modeled.

Mike
 

poppafred

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West Central Arkansas
Is it an inverted V or a flattop? If a V, what is the height of the apex and the height of hte ends. If a flattop, what is the height of the ends?

Then, exactly what band(s) are you wanting it modeled for? The model will be completely different depending upon the band.

Now, I'm not claiming that I can model it for you. But I can tell you that all of the above need to be known before it can be modeled.

Mike
Inverted V, peak at 35 ft, ends at 10ft, interested in how it models out at 40m and 20m.
 

prcguy

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A standard G5RV as appeared in 1958 is a center fed 102ft antenna designed for some gain and good matching to 75 ohm coax on 20m only.

Since the feed line length determines the matching and different types of balanced line have different velocity factors you must tune the G5RV feed line for a good match on 20m unless you have the exact type previously used and verified on another antenna.

On all bands except 20m a G5RV is a random length dipole and requires a tuner but fortunately it's long enough to give reasonable performance down to 80m.

A better choice for most hamsters is its modern day computer optimized cousin, the ZS6BKW which has a good match on 40, 20, 17, 12, 10 and sometimes 6m without a tuner. It's about 94ft long with a balanced feed line around 43ft long depending on type.

So for about the same amount of wire, twinlead and effort you can make an antenna that works about the same as a G5RV and you don't need a tuner on most bands. Why would you ever look at the G5RV again?
prcguy
 
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