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Booty Monster's Vector 40000 thread on Eham
- Thread starter Marconi
- Start date
B
BOOTY MONSTER
Guest
B
BOOTY MONSTER
Guest
op:
That ain't right!! It ain't wrong either
QRZ.COM booty, hope those brass balls are made of stainless steel, carbonite, super krypto magnesium, nitro glycerin, anti corrosive, plastic compound.
so far my hairy buddies are dong fine without any armor plating
I try not to get into the WWRF verse E-ham Verse RZED threads because it usually winds up not being constructive in the end....but.
I think the presence of the WWRF has help "tone down" the Cb/other radio services verse Ham battle a bit, be it here or on other forums.
Also the attitude overall is starting to soften a bit as more new blood works it`s way into the hobby.
New/Younger Hams seem to be less inclined to "Jump on" older issues like ones that have caused problems in the past....seems that the hobby is starting to have a little more of a open mind, and embrace some newer ideas as they move along.
There will still be individuals that will stay stuck in a rut with there thinking.....but over-all I feel the attitude is becoming better.
73
jeff
I still can't figure out why people will trust a $100 software program that doesn't line up with field tests over a $2500 modeling program that matches the field tests. One thing is for sure, if you want to start a thread that will receive lots of activity, start one about this antenna.
Donald's on QRZ thread said:
Well guys I just posted these Eznec model results for my Sigma 4, with currents turned on and in free space. Donald I think I get about what you're telling us when using CST in free space.
View attachment Sigma 4 Per Manual no mast 36'.pdf
The 2.27 dbi in free space at 17 degrees sure sounds like less than unity gain to me at zero degrees. One reason this angle is so high is because the cone has not been correctly positioned to confine all of the out of phase currents at the base of the vertical. Another possibility is the vertical may be too long and producing this extended out of phase current. Is this the new 3/4 wave or the old 7/8 wave?
The crossover point in phase along the vertical should occur right at the top of the cone. If you do this, the angle will come down closer to 0 degrees but the gain does not improve. No significant radiation is shown from the cone in EZNEC. That's not what I see in CST and in the field.
Here is the free space model with the cursor set at 0 degrees, and I don't think it is less than unity as you suggest.
View attachment Sigma 4 in free space at 0 degrees.pdf
It's actually significantly below unity gain Eddy. Unity gain is referenced against a half wave dipole and is 2.15 db over isotropic or 0 dbd. Notice EZNEC says 1.64 dbi. If the Sigma really produced this EZNEC pattern it would have went the way of the Edsel 40 years ago.
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Ok, what does CST indicate for the gain of the New Vector 4000 in free space?
The company that built the model in CST says approximately 2 db. I'm in agreement with this and have found a slight bit more if the 1/2 wave you compare it to has to be side mounted on a tower in the field.
Here is my first try at using CMoM type antenna simulation software. It is not easy to work, or model, and is much harder to modify like Eznec. I does not provide near as much simple type information either.
I have a segment limit with this free version, so I can't model a Sigma to specs, but I did a 3/4 wave radiator with slanted up radials.
Here are two plots that indicate results in a similar fashion to CST. I have not quite figured out exactly what it is I'm looking at yet.
View attachment .75 wave CAD model with slanted up radials.pdf
I have a segment limit with this free version, so I can't model a Sigma to specs, but I did a 3/4 wave radiator with slanted up radials.
Here are two plots that indicate results in a similar fashion to CST. I have not quite figured out exactly what it is I'm looking at yet.
View attachment .75 wave CAD model with slanted up radials.pdf