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EZNEC Models of Your Favorite CB Antennas
- Thread starter CTStallion
- Start date
Hi you may find this helpful http://www.worldwidedx.com/cb-antennas/113183-4nec2-antenna-simulation-tutorial-youtube.html
Hey, that was GREAT! Tnx so much. Can you take a request? It's the next logical progression from the 1/2L dipole. It's called the Extended Double Zepp. (EDZ) Envision a dipole with each leg 0.64L long. (Familiar number?) For 11-meters, that's a dipole approx. 44 ft. in overall length. A simple quarter-wave matching section made from a length of 75 Ohm coax (1/4
L x the.velocity factor of that coax, usually 0.66) takes care of the match. I think you'll LOVE the results. I use one on 20-meters and it works great.
Vy 73 de Bert
WA2SI
Sent from my ADR6400L using Tapatalk
L x the.velocity factor of that coax, usually 0.66) takes care of the match. I think you'll LOVE the results. I use one on 20-meters and it works great.
Vy 73 de Bert
WA2SI
Sent from my ADR6400L using Tapatalk
B
BOOTY MONSTER
Guest
thanks for the models .... interesting .
if all these antenna were at the same tip height how much difference would be expected ... if any ? is a vector or 5/8 at 49 ft to the tip any better or worse than a vertical dipole or 1/4wgp at 49 ft to the tip ?
iv'e , also read that height determines TOA , not the antenna wavelength .
what's the truth ..... what happens in the real world ?
if all these antenna were at the same tip height how much difference would be expected ... if any ? is a vector or 5/8 at 49 ft to the tip any better or worse than a vertical dipole or 1/4wgp at 49 ft to the tip ?
iv'e , also read that height determines TOA , not the antenna wavelength .
what's the truth ..... what happens in the real world ?
ive heard thesame too bm. his modeling was on the same lenth of pipe which
should favor the longer antenna. but if ya mount them so the tips are same
i think the differences would be slim imho. no matter if its 1/4,1/2,58
B
BOOTY MONSTER
Guest
its actually a moot point for me . a 28-29 ft feed-point is the most i could hope for so the taller antenna will do the best for me irregardless ... as far as a omni goes .
i do wonder though , since a coil/loop/gamma can be used to tune almost any long length enough to make a meter happy ....... and if tip height is what matters most . why not just have a 5 ft feed-point (very easy to tune) with say a 54 ft or maybe even a 72 ft vertical . maybe spread some 9 ft wires from the feed-point for a GP
i do wonder though , since a coil/loop/gamma can be used to tune almost any long length enough to make a meter happy ....... and if tip height is what matters most . why not just have a 5 ft feed-point (very easy to tune) with say a 54 ft or maybe even a 72 ft vertical . maybe spread some 9 ft wires from the feed-point for a GP
Hotrod here are several Eznec5 overlay models I have with the tips at the same height.
View attachment Patterns with tips at the same height..pdf
Here is Booty Monster's idea for a 72' foot radiator modeled with Eznec 5 that is 5' feet above the ground with 1/4 wave horizontal radials. Looks like BM is really on to something here.
View attachment Booty Monsters idea of a 72' foot antenna.pdf
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B
BOOTY MONSTER
Guest
No Meglotron, no phasing coils or matching was done in these models. These are basic models of the physical structure dimensions as noted in the input. I didn't post such results, but the model's results do show the amount of mis-match noted at the feed point for such constructs however, and such information is found in the source data report.
The NTO is the Sirio New Top One that I modeled to specs? It is a Sirio knock-off of the old Avanti AstroPlane. Such results surely surprised me. My real world results, that I did last spring, also indicated this new antenna was very effective as compared to several others, much higher antennas, that I tested about the same time...including the Old Top One which is closer to the original design.
Below is the model that I posted earlier at 40' feet to the antenna mount.
http://www.worldwidedx.com/cb-antennas/101842-marconi-models-new-top-one.html#post282384
Hotrod, of course you're right, but I think BM was trying to be hypothetical. I could be wrong though.
B
BOOTY MONSTER
Guest
BM, here is my Wolf .64 ground plane. It has two coils on the radiator. IMO, the first coils is a phasing device intended to alter the current polarity at the first 1/8 wavelength of the 5/8 or .64 radiator, and this helps to eliminate cancellation in this area of the radiator...that would other-wise occur without such a coil over the insulator.
The other coil, up above, seems to be intended as an inductor that helps to raise the current distribution up further on the radiator...just as theory suggest that the top hat does as well.
However, in this case the top hat is rather small, and its affects will be minimal at best and therefore it is my opinion that its primary function is to help minimize the attraction of static and lightning.
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B
BOOTY MONSTER
Guest
thanks , i had forgotten about the wolf 64 .
what size and shape top-hat do you think would be best to "to raise the current distribution up further on the radiator" ?
what size and shape top-hat do you think would be best to "to raise the current distribution up further on the radiator" ?