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EZNEC Models of Your Favorite CB Antennas
- Thread starter CTStallion
- Start date
The advantage of having low radiation angle is always going to be a favorable factor for the 5/8w - compared to a 1/2w or 1/4w - despite what 'equal' height it is.
Good dirt will always be the other factor.
Location, location, location . . .
Good dirt will always be the other factor.
Location, location, location . . .
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Welcome to the forum 2RB.
Hy-Gain has posted here, http://www.cbtricks.com/ant_manuals/hygain/model_473/ad/index.htm, several different values from 4.0 - 4.75 db gain on their CLR2 over the years, but 12 db gain is a bit high IMO.
Can you post a reference for such gain as you note above?
so yes i'm eating crow for lunch,,, i misread the numbers.
here ya have it straight and true.
Could someone do one for the sirio tornado with a #2awg solid copper wire from base to ground. Feedpoint height is 27ft. If possible. Live In Daytona Bch, FL, area, flat land and am about 2-3 miles from beach. Thanks for any replies or help. Just curious. Don't have my Anritsu anymore or I would see for myself. Again thanks for any replies and/or models.
222DBFL, the Tornado is a classic 5/8, yours should perform like the classic 5/8 he did 3rd from the top.
After reading and comparing his graphs, I'm actually quite impressed with the .64, especially now that I see it has the highest raw gain of all, 3.37dBi @ 28°.
It's 3.37dBi @ 28° upper lobe beats both the 5/8 2.86dBi @ 32°, and the Vector4K/Sigma4 2.75dBi @ 27° while still maintaining a hair MORE gain (.07dBi) than the 5/8 at the low angle of 10°.
...and with only about a third of a dB less than the Vector4K/Sigma4 at 10°.
So much for all that hoopla about there being no difference between a .625 (5/8) and a .64.
...and that no one ever marketed a ".64" - R/S .64, Taylor GLR4, Imax, etc.
Yet there's more gain advantage over a 5/8 by the .64, 3.37 - 2.86 = .51dBi,
(AND at a slightly lower angle of 32° for the 5/8 vs 28° for the .64)
than there is by the Sigma4/Vector4K over a 5/8 (2.79 - 2.35 = .44dBi) - and that's insignificant?
The Sigma/Tagra/Vector/Larry's beats the 5/8 by .44dBi and everyone goes apesh!t & does backflips over it,
but puts down the .64 as an "insignificant difference" compared to a 5/8 even with a .51dBi improvement...???
HUH?? And I'll have to add, to be honest I don't really believe the Imax IS a .64.
- Remove 12" for the bottom mounting plate from the 24' antenna, then another 5" or so for the matching network and you have left exactly 22.6',
or a true .625 (5/8) at 27.185MHz, center of the US CB band.
Ah oh, I fear that may have been .03¢ worth
222DBFL, the Tornado is a classic 5/8, yours should perform like the classic 5/8 he did 3rd from the top.
After reading and comparing his graphs, I'm actually quite impressed with the .64, especially now that I see it has the highest raw gain of all, 3.37dBi @ 28°.
It's 3.37dBi @ 28° upper lobe beats both the 5/8 2.86dBi @ 32°, and the Vector4K/Sigma4 2.75dBi @ 27° while still maintaining a hair MORE gain (.07dBi) than the 5/8 at the low angle of 10°.
...and with only about a third of a dB less than the Vector4K/Sigma4 at 10°.
So much for all that hoopla about there being no difference between a .625 (5/8) and a .64.
...and that no one ever marketed a ".64" - R/S .64, Taylor GLR4, Imax, etc.
Yet there's more gain advantage over a 5/8 by the .64, 3.37 - 2.86 = .51dBi,
(AND at a slightly lower angle of 32° for the 5/8 vs 28° for the .64)
than there is by the Sigma4/Vector4K over a 5/8 (2.79 - 2.35 = .44dBi) - and that's insignificant?
The Sigma/Tagra/Vector/Larry's beats the 5/8 by .44dBi and everyone goes apesh!t & does backflips over it,
but puts down the .64 as an "insignificant difference" compared to a 5/8 even with a .51dBi improvement...???
And I'll have to add, to be honest I don't really believe the Imax IS a .64.
- Remove 12" for the bottom mounting plate from the 24' antenna, then another 5" or so for the matching network and you have left exactly 22.6',
or a true .625 (5/8) at 27.185MHz, center of the US CB band.
Ah oh, I fear that may have been .03¢ worth
So how much would one have to ADD to an IMAX to make it a true .64 wave at 27 flat?
Would another 80" or 90" do it?
I've modeled these antenna lengths quite a bit and those gain numbers just seemed awfully far apart to me... That being said, I think I can explain the difference with these models and my own...
I tend to use about one wavelength in height above ground, witch is near 36 or so feet for a CB antenna. I have used other heights as well, but this is the default starting point height I tend to use. As CTStallion's models are at a little over half that height to the feedpoint, the few inch difference between the various antennas current nodes would have more of an effect than at the higher heights I tend to use, and going higher than that would cause the difference to be even smaller. An example of this would be the .625 and .64 antenna models I made for Needle Bender not long ago, where there was a 0.09 dB difference between the same two lengths at one height, and the others I noted the oddity of the .625 wavelength antenna having better gain than the .64, which was a surprise to me, although, mind you, those antennas were over a different ground type and were all higher than even my one wavelength standard feedpoint height models.
To go a step further, the patterns are different between the antenna sets as well. The higher antennas show the dominant lobe as the lowest lobe, not the second lobe. This is another effect of antenna height... If the antenna was mounted directly over the earth the dominant lobe would be even higher than the ones CTStallion used.
I guess what I am saying is be careful looking at one set of models and making blanket decisions about antennas from them. There is more than the design of the antenna at play when modeling...
The DB
Am thinking 50' to 54' with my iMax.
Do a 50' push pole and 6' solid fiberglass rod and a tube of fiberglass over that for 1.25" and guide a foot below that and go from their.
Do a 50' push pole and 6' solid fiberglass rod and a tube of fiberglass over that for 1.25" and guide a foot below that and go from their.
First off, thx for all the replies from both NB and The DB. Heavy Metal, If you are after good local and long distance dx, that is a good height. Also why the fiberglass rod at the antenna? To isolate it? Just curious. Also add a dipole to your antenna array if you don't have one. Give one a try, they work well and are easy to work with if you have trees in your yard. Get it to 18ft which isn't much and it will reward you at times when the Imax won't. JMHO.
Yes it is to isolate it as I did here like this, but maybe do metal and do this again I was looking for lightest solution for mouthing it and still isolating it as well, even thought putting another metal pole into the top 1.25" section then putting an 1.25" fiberglass tube over it rather than doing a solid fiberglass pole over a hollow fiberglass pole.
This is on 2 10'6" fence rails right now.
I just stepped steel conduit down from 1 1/4", to fence rail top post to 1" steel conduit. Drilled all sections and used 1/4" ss bolts. This seems to have a bit more rigidity than 2 fence rails together. It puts me at 27ft to my feedpoint. Mine is mounted directly next to my chimney and Florida room, which is an alum. top porch. Using and A99 and have multiple ground rods as well as one directly from base of the A99 to a ground rod, then tied into all other ground rods. #2awg solid wire is what I used. Placed this ground rods near where the A/C water drains. And are you trying to place this antenna on top of another antenna? If so, steel conduit shouldn't affect the beam antenna under it too much. I've seen quite a few verticals over a beam. I'm sure someone will chime in about the effects of using a steel conduit. But other then that, why isolating it?? The mount that comes with it is made to go around a steel pipe. They build communications towers out of steel. If it had an effect on the antenna other than having a ground if one if used, they shouldn't bother the antenna one bit unless the antenna is looking for a ground. Or am I missing someting here? Just curious.
I grounded my iMax at one of the 4 places on the plate mount and boy was it crappy VSWR's even when I put it to a fence rail directly same thing VSWR's were crappy but when I isolated it wow good bandwidth, and it was not with it I have two with an extra mid section to boot. Same thing with second one somehow better isolating it from touching other metal, hmm wonder why this happens?