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A99 vs dipole
- Thread starter kaos513
- Start date
Are you looking to purchase or build?
Not to give a canned answer but they both will work well...it just depends on what you are comparing it to. I'm sure other will chime in and share their experiences.
You may already have the components on hand...the Dipole is easy to build and you can be on the air quickly.
For my station, I run an old CLR-2 vertical for 10/11m along with a horizontal dipole (80-10m) and...a ground mounted Hustler 4BTV vertical (40-10m). Each antenna has it's strengths and weakness. When I talk to the local group, I use one or both verticals. These antennas are vertically polarized where my dipole is horizontaly polarized. Good luck!
Not to give a canned answer but they both will work well...it just depends on what you are comparing it to. I'm sure other will chime in and share their experiences.
You may already have the components on hand...the Dipole is easy to build and you can be on the air quickly.
For my station, I run an old CLR-2 vertical for 10/11m along with a horizontal dipole (80-10m) and...a ground mounted Hustler 4BTV vertical (40-10m). Each antenna has it's strengths and weakness. When I talk to the local group, I use one or both verticals. These antennas are vertically polarized where my dipole is horizontaly polarized. Good luck!
DXbarefoot, if both the CLR-2 and the 4BTV are close to the same heights, could you tell us how TX/RX signals compare for the CB frequencies with local contacts? If not, would it be too much to ask to maybe check such a test out and report in this thread? I'm curious.
513, I could post an Eznec model over real Earth and in free space for both designs for an A99 and a Vertical Center Fed Dipole, but the patterns are virtually the same. The gains are a little different with the edge going to the VCFD. The dipole also shows a little better angle to the horizon, but it is not much. Let me know if you wish to see the Eznec patterns.
In a practical way the CF Vertical Dipole made of wire would be more difficult to support and mount, but it can be done. You could also use aluminum tubing and offset it to a mast about 3' feet or more to one side.
A99 isn't a dipole, its an end fed 1/2 wave with very lossy coil system like a silver rod, it uses your coax as a counterpoise unless you prevent it.
dipole would be slightly better, especially if designed as a T2LT which is a centre fed coaxial dipole that can be taped/cable tied to a 10 metre telescopic glass fibre mast.
Its basically a 1/2 wave Gainmaster and has all the design advantages Gainmaster does including a 5 turn 4 1/4" rf choke that also acts as the end of the lower element,as well as choking common mode current, and as it only takes up top 6m or so of mast, you have plenty isolation from any mast or building you want to mount that on.
can be very portable or 10m mast can be building/mast mounted or can even be hung from a tree without a mast, takes advantage of the RF skin effect,
very effective, most importantly as its made from rg213/u or rg58 it is very cheap and a 83-1sp/pl259, although you could use different cables but choke would vary with different velocity factor cable.
just as easily make a tree or telescopic fibreglass mast supported 1/4 wave groundplane too that will perform as well if not better than any Silver Rod or A99, its just a centre fed dipole, with the lower half converted to radials raised for slightly more efficiency and better match to 50 ohm coax. Again costs pennies
dipole would be slightly better, especially if designed as a T2LT which is a centre fed coaxial dipole that can be taped/cable tied to a 10 metre telescopic glass fibre mast.
Its basically a 1/2 wave Gainmaster and has all the design advantages Gainmaster does including a 5 turn 4 1/4" rf choke that also acts as the end of the lower element,as well as choking common mode current, and as it only takes up top 6m or so of mast, you have plenty isolation from any mast or building you want to mount that on.
can be very portable or 10m mast can be building/mast mounted or can even be hung from a tree without a mast, takes advantage of the RF skin effect,
very effective, most importantly as its made from rg213/u or rg58 it is very cheap and a 83-1sp/pl259, although you could use different cables but choke would vary with different velocity factor cable.
just as easily make a tree or telescopic fibreglass mast supported 1/4 wave groundplane too that will perform as well if not better than any Silver Rod or A99, its just a centre fed dipole, with the lower half converted to radials raised for slightly more efficiency and better match to 50 ohm coax. Again costs pennies
"Doc, I tried to be on the safe side and claim I did see a little difference in gain between these two...just in case someone asked me to post the results. I could have just as easily said, I did not see a huge difference. Is that better for you?
Do you think when I decide to do a model, I know before I start what the end results will be from the beginning? God is capable of such things, but me thinks you give me too much credit.
You know for a long time I have found real life reasons to question a lot of CB claims about CB antennas in particular. From my first posts I was claiming I saw little to no difference in performance among all the different CB vertical antennas I have owned and tested. Here again I tested another way using Eznec and see a little difference. I am at least consistent.
When I started posting videos, you and others questioned how and what I did in that effort of comparisons. I found wisdom in much of those words, and I am convinced that it is nearly impossible to show definitive results at the level of testing most CBr's are capable of. Like you say often...there are just too many variables to be certain.
I thank you and others for showing me the light in this regard, but I still see very little difference in my real world testing of the various vertical antennas I own. At the very least the differences I tend to see are so small...as to be fruitless to argue.
I think this is what this thread by 513 is suggesting to him in answer to his question...each of us just said "it" in some different ways.
Sorry Marconi, I wasn't giving you any credit for what you said by what I said. What I said is just a simple fact.
As for those antenna modeling programs, I've played with them for years. They can certainly be enlightening, but they are far from infallible (the author will tell you that). They can only give you a probability, nothing factual.
- 'Doc
As for those antenna modeling programs, I've played with them for years. They can certainly be enlightening, but they are far from infallible (the author will tell you that). They can only give you a probability, nothing factual.
- 'Doc
Hey Jazz. I think our friend W9cll was only suggesting these two produce very similar RF patterns in that they both have a current node at each end, and a current maximum in the middle...regardless of how this 1/2 wave radiator is fed.
Compare the red lines in the two antenna views below. The RF patterns are also very similar.
That is a dipole in a generic sense.
Below are the two models I referenced. Note the dipole model in Free Space was done without the mast included...as it should be using Eznec's Free Space feature. I mentioned this issue in an earlier post, and I was not sure about this fact.
View attachment A99 vs. dipole.pdf
Besides the differences in feed point locations, and the difference in balance or lack thereof at the feed point on these two, the differences in matching results using Eznec may technically play a part in the small differences in performance results and angle we see. This is an assumption on my part, and if it is not the case, the real answer is above my pay grade.
Compare the red lines in the two antenna views below. The RF patterns are also very similar.
That is a dipole in a generic sense.
Below are the two models I referenced. Note the dipole model in Free Space was done without the mast included...as it should be using Eznec's Free Space feature. I mentioned this issue in an earlier post, and I was not sure about this fact.
View attachment A99 vs. dipole.pdf
Besides the differences in feed point locations, and the difference in balance or lack thereof at the feed point on these two, the differences in matching results using Eznec may technically play a part in the small differences in performance results and angle we see. This is an assumption on my part, and if it is not the case, the real answer is above my pay grade.
One uses a very lossy coil matching system, where the other's main loss are from a slight feedpoint mismatch in swr that will vary with height/placement but i doubt will be as much as those tiny narrow coils in A99.
I apologize but I haven’t figured out how to insert the Quotes box.
Following up to Marconi's request...(DXbarefoot, if both the CLR-2 and the 4BTV are close to the same heights, could you tell us how TX/RX signals compare for the CB frequencies with local contacts? If not, would it be too much to ask to maybe check such a test out and report in this thread? I'm curious.)
Without getting too technical here are some differences between my two setups for 11m TX/RX…
The two antennas are not on the same horizontal plane. The CLR-2 feed point is at 20’ and fed with 50’ of Belden RG8X. The 4BTV is mounted at ground level with the feed point aprox 8” above the earth and has two ground radials per band stretched out from the base. This is fed with 100’ of Belden 9913. To provide a visual, the 15m trap is the top of the 10m part of the antenna and is aprox 7’ above ground.
• Stations 30 miles away…The CLR-2 has a 2-3 S-unit gain over the 4BTV for TX/RX.
• Stations 45 miles away…The CLR-2 is 2-3 S-units down and many times I can barely hear them with the 4BTV for TX/RX.
• One station who is 60+ miles away…I can usually talk to him on one antenna or the other but usually not both at the same time unless propagation changes. That's cool to experience when that happens!
• 10m DX – Due to the varying take off angles, I will switch between antennas to get the best signal. For example, I may hear Missouri and Louisiana on one and Arkansas on the other…
Following up to Marconi's request...(DXbarefoot, if both the CLR-2 and the 4BTV are close to the same heights, could you tell us how TX/RX signals compare for the CB frequencies with local contacts? If not, would it be too much to ask to maybe check such a test out and report in this thread? I'm curious.)
Without getting too technical here are some differences between my two setups for 11m TX/RX…
The two antennas are not on the same horizontal plane. The CLR-2 feed point is at 20’ and fed with 50’ of Belden RG8X. The 4BTV is mounted at ground level with the feed point aprox 8” above the earth and has two ground radials per band stretched out from the base. This is fed with 100’ of Belden 9913. To provide a visual, the 15m trap is the top of the 10m part of the antenna and is aprox 7’ above ground.
• Stations 30 miles away…The CLR-2 has a 2-3 S-unit gain over the 4BTV for TX/RX.
• Stations 45 miles away…The CLR-2 is 2-3 S-units down and many times I can barely hear them with the 4BTV for TX/RX.
• One station who is 60+ miles away…I can usually talk to him on one antenna or the other but usually not both at the same time unless propagation changes. That's cool to experience when that happens!
• 10m DX – Due to the varying take off angles, I will switch between antennas to get the best signal. For example, I may hear Missouri and Louisiana on one and Arkansas on the other…
I learned a long time ago that modeling antennas and real world performance can vary drastically. If your a ground programming guru then by all means it will be close.the exact ground conditions have to be programmed and all surrounding objects within 3 wavelength as well "this all has effect on real world performance".
The #1 loss of all properly built antennas is ground loss. As the 99 is a "groundless design" along with its poor matching will have less real world performance then one built correctly.
I did a comparison of an imax 2000 vs a simple cfdp. In modeling the imax showed some gain over the cfdp"little".
Test was simple . 8 locals varying from 10 to 30 miles were used as a reference for transmit and received and an oscilloscope was loosely connected to measure peak received ."bnk 100 mhz " .
All tests were done on 10 meters with a yaesu 2000d ."yes I'm a ham".
All results were taken from the imax first and recorded.
The cfdp was actually built on the imax via 2 inch braid and heat shrink to hold it in place . Since the center of the cfdp was about 9 feet taller the mast was lowered 9 feet so the current maximum of both antennas would be tested at same hieghts.
The results were from 3 db gain from on site to 15 miles out ..at ruffly 30 miles out had a gain of 6 db "1 S unit" no doubt lower take off angle . Also less noise was heard on the band as well.
Not truly a professional test by any means ..but does show the effect of ground loss on these two types of antennas
PS the mast is a 45 foot push up pole fully raised for the imax and lowered 9 foot for the dipole .
73
The #1 loss of all properly built antennas is ground loss. As the 99 is a "groundless design" along with its poor matching will have less real world performance then one built correctly.
I did a comparison of an imax 2000 vs a simple cfdp. In modeling the imax showed some gain over the cfdp"little".
Test was simple . 8 locals varying from 10 to 30 miles were used as a reference for transmit and received and an oscilloscope was loosely connected to measure peak received ."bnk 100 mhz " .
All tests were done on 10 meters with a yaesu 2000d ."yes I'm a ham".
All results were taken from the imax first and recorded.
The cfdp was actually built on the imax via 2 inch braid and heat shrink to hold it in place . Since the center of the cfdp was about 9 feet taller the mast was lowered 9 feet so the current maximum of both antennas would be tested at same hieghts.
The results were from 3 db gain from on site to 15 miles out ..at ruffly 30 miles out had a gain of 6 db "1 S unit" no doubt lower take off angle . Also less noise was heard on the band as well.
Not truly a professional test by any means ..but does show the effect of ground loss on these two types of antennas
PS the mast is a 45 foot push up pole fully raised for the imax and lowered 9 foot for the dipole .
73