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francis amazer

W5LZ

Crotchety Old Bastard
Apr 8, 2005
6,832
889
173
Oklahoma
freecell,
Then here is your chance to enlighten this 'thick' person. How does increasing the apparent diameter of a conductor contribute to increasing gain of an antenna system?
The apparent, or effective diameter of an element, it's thickness, can and certainly does have an effect on the required length of that element for resonance. It can, to some limited degree, effect the usable 'bandwidth' of that radiating element. That's been a 'known' for quite some time, eg: 'fat' antennas, 'cage' antennas. Depending on it's limitations, an antenna modeling program (Nec2) will show this 'bandwidth' characteristic quite clearly. None of that increases that antenna's gain by any practical or realistic degree. That's from the theoretical stand point of modeling programs, and from practical experience (and not just my experience, by the way).
So show me. I am waiting eagerly for enlightenment.
- 'Doc
 

freecell

BANNED
Apr 6, 2005
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"How does increasing the apparent diameter of a conductor contribute to increasing gain of an antenna system?"

no one said that it did.

multiple radiators fed in phase produce pattern compression in the elevation plane which results in increased gain at more advantageous take-off angles.
 
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Highlander_821

Amour d'Ecosse
Apr 2, 2005
1,090
29
58
Central IL
So it works in some similar way to the way an omnidirectional 4-element collinear array for 2 meters works, to produce gain towards the horizon over , say, that of a single quarterwave element antenna?
 

freecell

BANNED
Apr 6, 2005
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same principle. a single end fed full size quarter wave radiates a high amount of energy skyward or at high angles in the elevation plane. the downward compression of this energy results in eliminating radiation wasted at higher less advantageous angles.

as in the 2 meter example that you used, this downward compression results from the stacking of additional elements in the vertical plane. in the TriQuad, this same compression is achieved using a plurality of elements (12) fed in phase in close proximity to one another with initial antenna currents in elements tuned at, below and above resonance reinforcing those electric fields at lower angles, eliminating wasted skyward radiated energy. the ability of an antenna to eliminate radiation in undesired directions and focus it into the direction desired is the definition of antenna gain.
 

Marconi

Usually if I can hear em' I can talk to em'.
Oct 23, 2005
7,190
2,249
343
Houston
and old 'Doc is off again on foot down the road to get some more smokes, saying "thingy-dinga, thingy-dinga, dingy-dingy, is a thingy, sort a."

I love it when things come together for good.

sorry 'Doc the devil made me do it.
 

unit_399

EL CAPO
Jun 17, 2008
1,715
1,745
173
ALEJANDRIA, COLOMBIA SA
Another big advantage for using a quad disk is that having 4x the antenna surface area would allow the antenna system to capture more rf and present a much stronger signal to the receiver rf amplifier. I would think that this would really help pull some of those hard to hear stations up out of the "mud".

- 399
 

old bear

Member
Jan 1, 2009
5
8
13
NW Arkansas
the Francis DiBar supports 2 CB50 Amazers for increased gain over a single CB50. the Quad Disk supports 4 CB50's for the most powerful, broadbanded mobile antenna ever built for 11M. see the First Picture link on the page linked to above. the TriQuad Mobile Array covers 21 - 33 Mhz. and never sees anything higher that a 1.5:1 SWR across the entire range.
I have a bar that uses the 3 5x5 Francis antennas. EDIT: I may have misremembered. I believe it is two antennas instead of 3. I remember the system used a on-concuctive spreader about 3/4 of the way up to fan out the antennas. I'm looking for directions on how to set this system up. I've never used it but a UPS driver friend did and it worked great! He's gone now as is the tech that set it up for him, and I'm old can't remember how it was done exactly. Any help appreciated.
 
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ChrisBama351

Member
Dec 14, 2013
28
4
13
Colorado
"The reason given for discontinuing the 8' antennas had to do with shipping costs and issues. They didn't sell enough to make it worthwhile. This came directly from a Barjan employee to me."

yep, that's the story that was put out for public relations consumption. they were discontinued because they couldn't keep the studs on the bottom of the shafts. i have several here on display that make it painfully obvious that they were not able to exactly duplicate that part of the manufacturing process.

in the meantime i'm still selling Original Francis CB50 Amazers from NOS. the barjan built defects remain in the corner of the shop for display purposes.

i have shipped 2 - 3 at a time out-of-state for as little as $14.75.
By any chance do You still have any Francis Amazers? Anyone know of any left to be had?
If we got enough orders together do You think we could have original Francis Amazer manufactured?
I would Love to have a couple or dozen Amazers again! My Favorite over the ss 102".
 
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ChrisBama351

Member
Dec 14, 2013
28
4
13
Colorado
the CB50 Amazer outperforms the 102. two CB50's on a Francis DiBar produce even more gain and four CB50's on the Quad Disk blows the 102 away by 2 - 2.5 S-Units.
Anyone have any info or pic's for the Francis DiBar or Quad Disk. I Love the Amazer but never herd of the Francis DiBar or Quad Disk. I get the concept but would like to see more or know the spec's. Would just like to see their design. I would Love to have a few Amazers if any were still around.
 

ChrisBama351

Member
Dec 14, 2013
28
4
13
Colorado
the Francis DiBar supports 2 CB50 Amazers for increased gain over a single CB50. the Quad Disk supports 4 CB50's for the most powerful, broadbanded mobile antenna ever built for 11M. see the First Picture link on the page linked to above. the TriQuad Mobile Array covers 21 - 33 Mhz. and never sees anything higher that a 1.5:1 SWR across the entire range.
Any idea what link that was? I don't see it and it probably doesn't work anymore anyway. More importantly Anyone have the info from his link?
 

ChrisBama351

Member
Dec 14, 2013
28
4
13
Colorado
I have a bar that uses the 3 5x5 Francis antennas. EDIT: I may have misremembered. I believe it is two antennas instead of 3. I remember the system used a on-concuctive spreader about 3/4 of the way up to fan out the antennas. I'm looking for directions on how to set this system up. I've never used it but a UPS driver friend did and it worked great! He's gone now as is the tech that set it up for him, and I'm old can't remember how it was done exactly. Any help appreciated.
Yes, Me too, I'm looking for directions on how to set this system up.
I think it is like 2 hots with a director and reflector but would like to see there design.
ala"Bama" 351 Colorado
 

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