Sigma IV for FM Broadcast!

[Master Chief]

The Dominator® antenna was developed for FM Broadcast in 1996 by Norwalk Electronics. Large volume sales began in 2003 with the explosion of the LPFM market. The Dominator® is a high gain vertically polarized .82 wave Coaxial J-pole. It is the coaxial cone at the base of this J-pole that allows us to go beyond the standard 1/2 wave and 5/8 wave designs by forcing the angle of radiation down on the horizon.

http://www.fmbroadcastantenna.com/dominator.html

It says .82 wave. The pattern looks great and supports freecell's and bob85's claims although scaled for the VHF band. They also call it a j-pole. Who else has called this a j-pole in the past? :twisted:

Check out the video where they smoke a gamma match from a clone.
http://www.fmbroadcastantenna.com/clone.html

While its still my opinion that this is not the best antenna for CB, it still is my all time favorite looking antenna!

 

[bob85]

see my ezbob softare aint bad after all lmao.

who called them a jpole? sirio

it is still my beliefe that the vector 4000 setup correctly is the best performing cb base antenna available, i just wish you were over here so i could prove it,


they seem to be cutting down sirio cb antennas for other bands, and contradicting themself to boot,
when they say no single antenna can beat the 5/8 6mtr 827 clone, i say want to bet,

theres just been a burst of activity locally with 4 people errecting the 4000 after seeing how one persons vector compared to his 5/8 groundplane, every one has reported the best signals and talking easier further than ever before and theirs are just set to factory settings which for me aint right at all,
none are at all happy with the poor construction quality.

 

[Master Chief]

I told my wife I wanted an ezbob. She says its not as EZ as when I was 17. I told her I was willing to be patient if she was!

 

[Marconi]

it is still my beliefe that the vector 4000 setup correctly is the best performing cb base antenna available, i just wish you were over here so i could prove it,

theres just been a burst of activity locally with 4 people errecting the 4000 after seeing how one persons vector compared to his 5/8 groundplane, every one has reported the best signals and talking easier further than ever before and theirs are just set to factory settings which for me aint right at all, none are at all happy with the poor construction quality.

Hey Bob, can you give us some details about what you and your buddies are doing over there with that burst of activity? Can you tell us what you are finding out?

 

[bob85]

marconi we did some signal tests with different results due to our different signal meters but all reports are better than their old antennas,
radios used were my jrc135, ts850, ft847, 756pro2, 706mk2g and a few other hf sets and cb radios,
antennas tested at different heights upto about 40ft are vector4000, i10k, imax2000, sirio827, a99,

the results

1st vector 4000

2nd i10k

3rd sirio 827

4th imax2000

5th a99

the biggest change in signal was recorded on the ft847 but imho the 847 smeter shows small differences in tx power say 10w-50w as large differences in signal strength ( great for seeing any difference in antennas but not the type of smeter i like )

the least increase was recorded on my jrc ( 3db/s-unit ) and the pro2 which at s8 is even stingier to signal changes than my jrc,

one guy had a vector 4000 and an 827 up at the same time and they definately interact with each other spaced at just over 30ft, he thought the vector was better but not in all directions,
he swapped the vector for a 3 ellement beam with one of my buddies who replaced his 827 with the vector and saw better tx/rx in all directions,
the main difference between the vector and a 5/8 is that you can hear and talk to distant stations that aint there on the 5/8 antennas at the heights we use them,

its no different for me as my circle of workable stations has shrunk since i went to the groundplane,
the difference increases as you bring the antenna closer to the ground,
if anybody here had their antenna mounted at 72ft+ to the feedpoint which they dont i would expect less of a difference but past experience when i did have my antennas mounted that high in an open field tells me the vector would always be ahead over the shorter antennas,

the upside is i can talk short skip easier than i can on the vector but it dont talk longer range skip as well as the vector and i cant talk to my buddies at the coast since i took the vector down, oscar took down his 827 and put up a new vector,
hes talking to the same guys on the coast easier than ever before,

the 756pro2 guy said hes wiping his tv at lower power settings than he was on the 827 but nobody else is having any such trouble and none of them have spent any time at all adjusting the antenna for signal strength at 60+ miles either,
they just set it at factory marks which is wrong for where we use them both frequency and proximity to ground and surroundings,

imho testing antennas should be done with just one antenna errected in the same place as the one you want to compare it to and within a very short period of time between tests,
testing 2 together will have you thinking all kinds of crazyness

make what you will of my ramblings but you will not find anybody over here that does not say the sigma/vector is easilly the best performing antenna they ever used regardless of what they think of the construction quality,

i dont make/sell/installl antennas for monetry gain and have nothing to gain by telling anybody which works the best for me
i dont just look at what makers/sellers have to say to make up my mind which is best,
the other guys who use them can make up their own minds which works best for them,
as far as im concerned to each his own

 

[Marconi]

Very good Bob. If I can, I will embed my remarks or questions inside of your post!

marconi we did some signal tests with different results due to our different signal meters but all reports are better than their old antennas,
radios used were my jrc135, ts850, ft847, 756pro2, 706mk2g and a few other hf sets and cb radios,
antennas tested at different heights upto about 40ft are vector4000, i10k, imax2000, sirio827, a99,

the results

1st vector 4000

2nd i10k

3rd sirio 827

4th imax2000

5th a99

the biggest change in signal was recorded on the ft847 but imho the 847 smeter shows small differences in tx power say 10w-50w as large differences in signal strength ( great for seeing any difference in antennas but not the type of smeter i like )

the least increase was recorded on my jrc ( 3db/s-unit ) and the pro2 which at s8 is even stingier to signal changes than my jrc,

All that testing must have been a real ordeal. Because receivers and meters respond differently, I think it’s important to figure out the individual rig responses ahead of time, so you’ll know what to expect during comparisons. Some rigs are just not very responsive to changes, even as large as 1S at times. You obviously are aware of this because you tell us you did some checking to determine the response nature of the rigs you used. Did you check these rigs at your station or is this just the mix of rigs that the guys around you had to work with? I just wonder how you can really tell this type of difference without having two antennas up and working during testing at some point with each of these rigs?

I use an old transceiver with a big analog meter. It has no filtering, AGC, noise limiting, or blanking. The audio out is not High FI, but it hears noise, static, and audio just fine. The meter seems to be very responsive to differences in signals up to S9, and it’s a bit less effective when signals are over S9. It does a much better job comparing signals than my TS570D, which takes a S1 signal or larger to make a one bar difference on the meter.


one guy had a vector 4000 and an 827 up at the same time and they definately interact with each other spaced at just over 30ft, he thought the vector was better but not in all directions,

How do you tell that they are affecting each other? When I have two antennas up and comparing I also find the direction of the signal sometimes makes a difference. I figure this happens due to some interference in the path between stations, but I have never figured out exactly what is going on.

he swapped the vector for a 3 ellement beam with one of my buddies who replaced his 827 with the vector and saw better tx/rx in all directions,
the main difference between the vector and a 5/8 is that you can hear and talk to distant stations that aint there on the 5/8 antennas at the heights we use them,

Bob, to be honest, I have never had such an experience with any two of my antennas unless one was just noisy with static and the other was real quite. Then it was not an issue of one antenna being stronger than the other. I have had stations tell me that one antenna showed a better signal than another, but I never lost a contact such as you describe.

its no different for me as my circle of workable stations has shrunk since i went to the groundplane,
the difference increases as you bring the antenna closer to the ground,
if anybody here had their antenna mounted at 72ft+ to the feedpoint which they dont i would expect less of a difference but past experience when i did have my antennas mounted that high in an open field tells me the vector would always be ahead over the shorter antennas,

I don’t doubt your word here. My old Sigma always seemed to make a good signal no mater how high or low it was. I think this is one of the benefits Avanti describes in the Patent is the reason it performs better compared to a 5/8 wave which is supposed to have a lower take off angle pattern. They claim the 5/8 looses its pattern due to the affects of local objects nearby the antenna, which skews the maximum lobe of the pattern to a higher angle. I also think placing a 5/8 up approaching near to 2 wavelengths also skews the pattern as noted above.

the upside is i can talk short skip easier than i can on the vector but it dont talk longer range skip as well as the vector and i cant talk to my buddies at the coast since i took the vector down, oscar took down his 827 and put up a new vector,
hes talking to the same guys on the coast easier than ever before,

Again, I figure this fits in with the statements above.

the 756pro2 guy said hes wiping his tv at lower power settings than he was on the 827 but nobody else is having any such trouble and none of them have spent any time at all adjusting the antenna for signal strength at 60+ miles either,
they just set it at factory marks which is wrong for where we use them both frequency and proximity to ground and surroundings,

What are you suggesting here? I have heard there are magical heights where the best local contacts can be made, but what can be done with the design and construction that will show improvement?

imho testing antennas should be done with just one antenna errected in the same place as the one you want to compare it to and within a very short period of time between tests,
testing 2 together will have you thinking all kinds of crazyness

I do not disagree. It surely would be better, but I find my signal reports from regular stations can change during the coarse of a day or less, so I’m not real sure. At least with testing two stations, baring the possible interaction that you speak of, that at the very least if conditions change it likely will not change the relationships the report shows for that time. That said, of course there is always a problem with one system (setup) being more effective that the other. I consider that a possibility, but I have never noticed a difference when switching antennas between my two setups.

make what you will of my ramblings but you will not find anybody over here that does not say the sigma/vector is easilly the best performing antenna they ever used regardless of what they think of the construction quality,

Well I have to agree with you again. I can’t say the Sigma I have is weak except for the way the gamma is attached at the feed point. My Sigma was picked up off of the mast during a terrible storm in my area and ended up in my neighbor’s hedges at the fence between our yards. This was about 20’ away. I guess it stopped there because that is all the extra coax there was out side on the lawn. This did not hurt the Sigma at all.

i dont make/sell/installl antennas for monetry gain and have nothing to gain by telling anybody which works the best for me
i dont just look at what makers/sellers have to say to make up my mind which is best,
the other guys who use them can make up their own minds which works best for them,
as far as im concerned to each his own

Same here. Sure would appreciate your remarks.

 

[bob85]

marconi i have never tested other peoples radios with my attenuator to see how linear and to what kind of scale their radios are, you just get a feel for that kind of thing when somebody is testing an amplifier and you see 1 s-unit while your friend sees the signal jump from s8 to s9+60db,
the jrc is the most linear meter i ever had on any radio but its not good for seeing signal differences like some radios, i much prefere a large analogue meter like the ft990
remember we use fm so we usually have rock stable signals when its not very windy and theres no multipath type flutter ( no swing in my thing )

all i can tell you about the distance thing is from 2.5ft to 36ft to feedpoint at this location i can talk to stations on the vector that i cannot hear nor can they hear me on any groundplane antenna, im not suggesting its a gain thing just a pattern difference much like the imax vs i10k when mounted low down and i will agree 100% that the sigma style antennas work VERY well even with the mounting stub stuck in the ground when compared to other cb antennas at the same mounting height,

i asked my locals if they would come here and post what they thought of their antennas but they are not interested like i am, you guys are the only people i can talk to about cb antennas and im FAR from an expert nor do i claim to understand how they work, i just know what works best at this and my parents house which are two totally different surroundings,

you can improve the vector anywhere you look because they are the weakest cb base antenna ever made whereas the avanti is VERY STRONG if you double skin the base section, mine stood 110mph winds that brought the top 40+ feet of scaffold pole down into a small wooded area spearing the antenna tip a good distance into the ground and it lived to talk another day undamaged,, youres blew away and survived too,

the one thing on the vector that is way stronger than the avanti is the gamma connection to the so239, without double skinning the avanti the ring connector breaks free of the so239 just about every winter,

i have said before that the 4 leg basket seems to work better than the avantis 3 legs even on the same radiator section,
the factory settings are for your midband freqs but we use 27.60125_27.99125mhz,
just keep playing with tapping point,radiator length and gamma setting while observing signal reports and bandwidth and you may see the same as me and my buddy, an increase in signal strength at distance and a broader bandwidth
if that makes no sense to the clued up guys then maybe they can explain the changes in signal with different settings i surely cant.

 

[Marconi]

Thanks for your comments Bob. I guess I misread the part about you and your buddies testing antennas as a group. When I test or compare, I can hardly keep up with my own record and still have any meaning later on. I often find I did not write something down, make sense in doing so, or check something else in the process. I also find dealing with others is, for sure, pretty much out of the realm of possibility. This is why I was so curious about how you did what you did thinking you were different and had the interest. I think you are correct though---I would just have to be there to really understand what you were doing and how you got your results. Sometimes it is just hard to explain what we are thinking and doing.

One issue I might take with you is your comment in the end of your post about having to tune for the frequencies you work and the affects on field strength by tweaking. I can say I believe you, but personally I have never noticed an affect of field strength changes simply by tuning. I have noticed such changes when altering the design or structure of the antenna substantially, but not in the process of tuning. I could be wrong, but I think your antenna’s bandwidth provides a suitable range to work with in the area you note just with a bit of standing wave present. So I would think some find tuning would fix that, and cannot imagine that having any important affect on field strength. I have never really tested this approach, but some of the worst tuned antennas I have show to be effective under testing in the far field and I have never seen a field strength difference in the near field, unless I changed the design somehow. Even then the difference is pretty marginal. I will just have to one day follow your lead here and be checking the bandwidth and doing some on air signal reports. I also disagree with when you suggest that broader bandwidth is more effective. This is certainly a topic for argument, but within reason I find even in vertical antennas, that broader bandwidth relates to a bit less effectiveness in the near field for sure. Bandwidth is an important characteristic, but am I wrong about this in the far field?

It seems I’m the only one around my QTH with interest in antenna theory and testing. Can’t get anybody around here to talk about anything specific regarding antennas. It’s all right I suppose, but I don’t participate much as a result. Seems most guys just want to argue, fuss, and carry on about a lot of meaningless dribble most of the time. They don’t even talk about sports, fishing, or movies around here locally. Give my bunch a specific topic to discuss about antennas, where real differences of opinion and ideas might exist, and all of a sudden you’re bringing up one of the old taboos like religion or politics. Back in the days, I was part of a group that discussed radio and antennas most of the time on the radio. Ain’t that strange? Most of the good ones are gone now. I recall having hour-long discussions on the phone or meeting somewhere and talking about antennas and our radios. Then later we might follow up on the air for others to chime in. I think we learned from such efforts.

Even now, I can’t pretend to I understand how you did what you did in your testing, making judgments, and the comparisons you describe in your first paragraph. Suffice it to say I believe you, and your opinion about the Sigma IV design is also held by me. Even so, I can’t reason out how this long element seems to defy relative and published evidence, thoughts, discussion, and ideas on the subject. I am reminded of what happens to the radiated pattern when using an effective long wire. It confuses me still when I read the hype that goes along with the Dominator antenna Master Chief presented to us. I can’t get past the image of the pattern presented on that site. We would all say it is very good pattern, even ideal, but in the real world it is not real where and how an antenna has to exist. This image is that of an antenna sitting directly above an infinite ground, meaning perfect relative to the earth being present. Even if one could raise this one up to a height where the earth did not seem to matter you still could not avoid the affects of the earth, the support structure, and the coax on the resulting pattern. I suspect that the pattern in this case, with the antenna raised very high, would still be totally different and not to our liking compared to that presented. And, if installed directly on the earth itself, the antenna would again show another completely different pattern, probably not to our liking.

I recall that when I was attempting to read and understand the Patent on the Sigma, I did not sense this same hype as noted in the Dominator ad. Even so, I did not come away with a full explanation as to how this design overcomes the affects of being way too long and still be effective as a vertical radiator either. That is unless, Master Chief is correct in that only the top 1/2 wavelength radiates and that by raising this radiating element up about 8’ higher than a traditional ground plane at the same feed point elevation gives it an advantage just by the increase in height alone. I also figure that if Master Chief is not correct then the information in the articles noted below are wrong also.

I think maybe you have read an article entitled: The 5/8-Wavelength Antenna Mystique, by Donald K. Reynolds K7DBA. Probably you have also read Cebik’s article on the same subject covered by the article. Reynold’s article may be on the Internet. For sure it is published in The ARRL, Antenna Compendium, Volume 1. Cebik’s work is on his Website I think under a similar title. As I read these, the gist is that these longer antennas all fall short in real performance as compared to their theoretical performance, and end up about the same as using a traditional 1/2 wavelength and in some cases even a 1/4 wavelength ground plane antenna. We hear all the time from others and for sure we have ourselves made comparisons where we saw differences that favored the longer radiators. So, are these guys all wet in their work at understanding, are their facts and conclusions all wrong?

I guess we all understand that testing on a controlled test range with the use of science, math, and computers is important to understanding the theory and principals under which these antennas work and how structural changes in design affect the results. However, evidence at our own hands often proves these elaborate and scientific procedures to fail us when we compare the antennas in the real world. There are just too many variables around to ever really make a definitive statement as to which is best in all cases, but I think the old Avanti Sigma IV comes close and next to that I think my old Starduster is top notch when I can get the tip of it up as high as your antenna. Why you might ask? Well maybe next time I will talk about the Starduster.

 

[bob85]

hey move to yorkshire, put up with gas at $10 a gallon bring MC and we can have some real fun lmao,

no i dont think the data on 1/2waves 5/8waves is wrong, i think they are pretty well understud by some people ( not me ) i just think the same people have more than likely never tested the avanti design in its different permutations and most average guys just read a book and take it as read that 5/8 is the best or is it .64 hmmm, after that i dont dissagree at all that in a regular groundplane antenna the pattern breaks up, does the avanti stop that happening or is it modifying the pattern of mc's 1/2wave radiator i have no idea, i do have a decent field strength meter but how do i know where the signal is comming from if i hold the test antenna near or level with the basket on a sigma, i cant see rf.

i wonder if sirio have tested the vector, they used to be just like most antenna makers claiming stupid gain claims from antennas that could not do what they claim but more recently they claim much more reasonable figures and the vector is at the top of their range in gain and performance,
they have an anechoic chamber for testing smaller antennas and do some kind of measurements on larger antennas though looking at the pictures on their research and development section i think they have too many obstacles in the nearfield to do any propper testing where they claim its out in the open,

we all read the patent and each make up our own mind as to what avanti mean in what they say,
all i can say is that design for me at least outperforms all others discounting the vector which has the edge imho and avantis claims seem to fit what i see, they say the radiator can be lengthened but they dont say what that will do for performance,

since nobody in authority has tested that design and documented the results for us all to read its hard to determine just what those test results would be,
the 5/8 on the other hand is very very common, lots of research has been done and its there for everyone to see,

all the people saying anything positive about the sigma design are selling something and finding a person that wont make his mouth say anything if it makes his wallet fatter is gonna be very hard indeed,

the colinear version is nothing new to me, i have talked about making one for years,
they actually did it good on em,
they also claim their .82 wave will outperform the 5/8, are they just parroting what avanti say?
is it just a fluke that i get the best results when my antenna is a little shorter than sirios settings which they claim to be 7/8wave?
are they just talking bs to make a fast buck?,

the bandwidth / performance thing,
i dont blame you for been sceptical at all thats what we have been told for years but it is not what i see on my antenna,
are external things influencing what i see?,
no doubt they are but thats what i see,
there is a guy on the net that claims the gamma is at its best when the bandwidth is wide, is it cebic i dont remember?,
what he says contradicts the little i understand about circuit Q but it fits what i see in my basic tests,

 

[frogger]

I must say that BOB85 is correct ....these local and not so local breakers..to me who have put there new vectors up...all have increased..in signal.. .the most increased was from the a old guy called..peter...furthest...away from me...and i must say that all the antennas i have known that has been replaced by the vector..the vector always seems..to increased there signals and i have never heard anyone disapointed with the vector...only when the north winds BLOWS vectors will go The life span isnt long in the cold windy winter months :shock:

 

[T-bone]

see my ezbob softare aint bad after all lmao.

who called them a jpole? sirio

it is still my beliefe that the vector 4000 setup correctly is the best performing cb base antenna available, i just wish you were over here so i could prove it,


they seem to be cutting down sirio cb antennas for other bands, and contradicting themself to boot,
when they say no single antenna can beat the 5/8 6mtr 827 clone, i say want to bet,

theres just been a burst of activity locally with 4 people errecting the 4000 after seeing how one persons vector compared to his 5/8 groundplane, every one has reported the best signals and talking easier further than ever before and theirs are just set to factory settings which for me aint right at all,
none are at all happy with the poor construction quality.

I've got the Vector 4000 but have nothing to compare it to. I know a couple people that have them and swear by them. I like mine but it is pretty flimsy. One of the screws fell
out and a section slid into another so I gotta take care of that. There is also a slight bend
in one of the elements from wind. It has been subjected to some pretty tough storms but
the winds never exceeded 60 knots. Anymore than that I think would be it's death. I wish
they were better constructed. I do likes it's performance and the price is pretty cheap at
$110. If and when it breaks I'll replace it with an Interceptor or Mr Coily unless they make
an improved and more durable Vector.