Modified Vector 4000

[MrSuburban]

if i got the wrong information/impression and it can be built with a tapped coil please tell me what if any other differences have to be made on a vector for that matching system .

Apart for the mechanical considerations, the purpose of the matching device (beta, hairpin, gamma, T or whatever odd design) is to match the transmission line to the load. Also, just in case you heard otherwise, the kind of matching used has no effect on the gain or the overall performance of the antenna, assuming it has negligeable loss. It's ONLY a matching device, no more, no less and it has no "magical" properties

Booty not to be a ass but the internet is for sharing information, not sucking others dry. You cant expect people to do all the work and give away there work for the sake of trying to sound smart to people. Get out there and get your learn on post pictures if you have a problem then others will be happy to help. Thats what this hobby is supposed to be about but it has turned into Xerox the smart guys do the work and others want a free ride. Not saying that is you but in general thats what Cb has turned into profit from others hard work... Homie don't play that.

 

[bob85]

nice posty henry,

my ideas about the sigma style antenas come from 30 years of user experience,

i don't understand eznec but cebik did understand it and warned me that getting accurate results from eznec with the sigma style antennas would be very difficult, he never said impossible to model, only that getting accurate results would be very difficult,
from what little i have read there could be issues with that particular design for the reasons i mentioned earlier,

whenever a model does not show what has been repeatable here for 30 years without one instance of any 5/8wave been the equal of the sigma design it makes me suspect the model,
if the performance advantage of the sigma is not repeatable at other locations/ground types ect i would have to suspect that ground type could be responsible,
that does not answer why the sigma style holds its advantage to at least 73ft to feedpoint in an open field over avg/good ground,

i have no proven answer to why we see changes in signal strength as we change monopole and radial length other than we create changes in the relative phase of currents in the radials vs monopole currents,
i explained what i was doing and the observable effects to cebik and he said it was perfectly possible due to the none apparent co-linear effect,

regardless of eznec indicating about the same gain as a 5/8wave or not there is more than the 1db advantage over a 5/8wave groundplane that avanti claim when we compare a 5/8wave to a vector 4000 tuned for maximum signal in this area,
something is causing this effect

 

[BOOTY MONSTER]

Apart for the mechanical considerations, the purpose of the matching device (beta, hairpin, gamma, T or whatever odd design) is to match the transmission line to the load. Also, just in case you heard otherwise, the kind of matching used has no effect on the gain or the overall performance of the antenna, assuming it has negligeable loss. It's ONLY a matching device, no more, no less and it has no "magical" properties

Booty not to be a ass but the internet is for sharing information, not sucking others dry. You cant expect people to do all the work and give away there work for the sake of trying to sound smart to people. Get out there and get your learn on post pictures if you have a problem then others will be happy to help. Thats what this hobby is supposed to be about but it has turned into Xerox the smart guys do the work and others want a free ride. Not saying that is you but in general thats what Cb has turned into profit from others hard work... Homie don't play that.

i apologize .
ill try to remember to not ask you to explain your claims or share your work so i can try to understand it (or xerox it at some point) again .

 

[Shockwave]

I just want to thank everyone for their input and ask that we keep things professional here. There are few antennas as controversial as this. I also have to say whenever I am in the presence of someone who has more knowledge then me in an area I'm interested in, I'm the first to turn into a sponge and soak up whatever information is available.

I certainly do not want to offend any of the people who understand the proper use of EZNEC+ better then I do. This would be silly since I still have my training wheels on with this program. On the other hand I have to express with 100% certainty that this design produces a noticeable increase in gain over the 5/8 wave ground plane.

I've literally sold hundreds to my customers that were using a 5/8 wave with the guarantee that it will do just what we claim. Many of my distributors were skeptical at first and insisted on doing their own field tests prior to carrying the antenna. Some of these distributor have decades of experience in the broadcast industry and if I were wrong here, they would have been fast to call it BS.

This is not the case at all. I have two independent tests taken by one distributor that was sure the claims were false. Needless to say a month later his testing confirmed what we have been seeing for 15 years. I don't say this to belittle anyone's work with software modeling. I point it out for the same reasons Bob mentions. When the model does not match repeatable, in field tests, we are forced to believe the model is at fault and to try an improve it.

 

[CDX-007]

since a sigma 4 can't be made to work properly with a typical tapped coil type matching device it seems in the real world (at least in the sigmas case) matching devices can make a big difference . not in gain , but in the antennas ability to perform at its best .

......... of course i could certainly be misunderstanding something .

How do you know that the Vector can't be made to work with a typical coil type matching network? There are ways to add capacitance to the antenna without a gamma. The ability of a antenna to perform at it's best is measured in gain.

if i got the wrong information/impression and it can be built with a tapped coil please tell me what if any other differences have to be made on a vector for that matching system .

Apart for the mechanical considerations, the purpose of the matching device (beta, hairpin, gamma, T or whatever odd design) is to match the transmission line to the load. Also, just in case you heard otherwise, the kind of matching used has no effect on the gain or the overall performance of the antenna, assuming it has negligeable loss. It's ONLY a matching device, no more, no less and it has no "magical" properties

Booty not to be a ass but the internet is for sharing information, not sucking others dry. You cant expect people to do all the work and give away there work for the sake of trying to sound smart to people. Get out there and get your learn on post pictures if you have a problem then others will be happy to help. Thats what this hobby is supposed to be about but it has turned into Xerox the smart guys do the work and others want a free ride. Not saying that is you but in general thats what Cb has turned into profit from others hard work... Homie don't play that.

i apologize .
ill try to remember to not ask you to explain your claims or share your work so i can try to understand it (or xerox it at some point) again .

Shame on you Booty, you "Sponge"!!

WTF are you doing out here anyway, trying to learn?!?!?

Actually, you asked about modding the Vector for a non-gamma type of match and your reply was all about matching systems, ignoring the point of your question which was obviously about the length or design mods necessary for utilizing a coil-type matching network or another non-gamma type matching network.

I, too, was hoping for an answer to your question of how to add capacitance to the vector without going to a gamma match.

I was wondering if it would be to shorten this antenna which allegedly works so well because of it's length, or if adding a capacitance hat to a shortened version, (also defeating the ideal performing length in the vertical plane) would be it.

I just figured the gamma was used by all the manufacturers of this design over the last 30 years because it was the best matching device for the job, matching an inductively long antenna by adding a capacitive matching network.

 

[MrSuburban]

Shame on you Booty, you "Sponge"!!

WTF are you doing out here anyway, trying to learn?!?!?

Actually, you asked about modding the Vector for a non-gamma type of match and your reply was all about matching systems, ignoring the point of your question which was obviously about the length or design mods necessary for utilizing a coil-type matching network or another non-gamma type matching network.

I, too, was hoping for an answer to your question of how to add capacitance to the vector without going to a gamma match.

I was wondering if it would be to shorten this antenna which allegedly works so well because of it's length, or if adding a capacitance hat to a shortened version, (also defeating the ideal performing length in the vertical plane) would be it.

I just figured the gamma was used by all the manufacturers of this design over the last 30 years because it was the best matching device for the job, matching an inductively long antenna by adding a capacitive matching network.

If he wants to learn why dont you teach him 007?

A gamma is a capacitor with a series inductor if you cant figure out how to adapt one to a tuning ring to replace the one on the Vector nothing i can say will help. Like I said get your learn on, it is up to you to do your homework and try it for yourself. I charge by the hour let me know when you want the clock to start... :laugh:

 

[HomerBB]

Without any further thought the major problem I'd have trying to use a coil instead of the gamma is that the radials on this antenna are positive grounded to the vertical. When I use a coil I have the radials, as in GP, and the vertical isolated from each other.
There is likely more to this than I know so I'm listening, too.

 

[Shockwave]

In an effort to answer Booty Monster's question, YES. This design can be matched without any added capacitance. It's already been done with Sirio's CX line of antennas. Replace the gamma with a straight conductive rod (no cap). Tune the radiator length so that it's slightly capacitively reactive rather then inductively (cut it a little shorter). Then it's just a matter of finding a tap point from the rod to the radiator that gives a match. The good news it handles tons of power like this. The bad news is I can't for the life of me make this work quite as well as the standard gamma match.

 

[BOOTY MONSTER]

thanks guys .

 

[W5LZ]

"The ability of a antenna to perform at it's best is measured in gain."

No, it's not. Efficiency has nothing to do with 'gain'.
- 'Doc

 

[Marconi]

if someone was to homebrew a sigma 4/vector 4k style antenna would shockwaves design/measurements be better to go by ?

"For those that were wondering what my measurements on this antenna are......Here you go. The vertical whip is 29 feet 7 and 1/4 inches long from the bottom of the connector bracket to the tip of the whip. The four radial arms are 81 and 1/2 inches long from end to end. The loop is 129 inches in circumference. The gamma is simply adjusted for lowest VSWR. Sorry I did not measure the gamma and I did use a home made Teflon gamma match with a weatherproof HN connector."

BM, Homer is the guy you need to talk to about dimensions for your HM Sigma/Vector. My Sigma is 27'7" long, the radials are about 91" at a 1/4 wave I figure, and the hoop is a bit smaller in diameter and is about 94" in circumference at a 1/4 wave too, me thinks.

In my opinion the antenna is very sensitive to its construction, so much so Avanti basically built the kit as a plug and play kit. Everything seems to be pre-tuned, cut & marked, and specified as such in the manual. I would suggest once you get the construction under control for your HM, then you might try to make the antenna tune and work better being longer. A lot may depend on the radiator's diameter and taper lengths you use. Same might hold true with the Vector if you decide to use those measurements, but I've never seen one of those up close. Bob gave us the actual dimensions for the New Model Vector 4000. Might check his Photo-bucket folder or his album here on WWRF.

I spent a couple of hours setting up my New Sirio Top One per instructions. It tuned up almost perfect mounted where my Imax was yesterday, and unlike the Imax...it produces NO TVI type RF in my shack. Other than that the antenna looks to be another plug and play kit that is made pretty well. The tubing looks a little thin, but the base of the radiator is double walled for about 18" inches where you mount it, and that will give the top some good support. The antenna hangs down a bit over 4' feet below the mounting tubing provded. I think it is heavier than my Old model of the Top One too.

Not a very good picture and I'm not square between them because of the tree, but maybe you can get an idea of the height difference which is a bit over 14' feet to the tips while the bottom of the New Top One is a bit over 4' below the top of the coil on the Gain Master. I haven't compared them yet, but I think the 4' foot advantage may make some difference for the TO if I can add it back.

 

[MrSuburban]

"The ability of a antenna to perform at it's best is measured in gain."

No, it's not. Efficiency has nothing to do with 'gain'.
- 'Doc

So an inefficient antenna will have more gain than a efficient one?

When efficiency goes up what does gain do?

 

[MrSuburban]

The bad news is I can't for the life of me make this work quite as well as the standard gamma match.

do you think shortening the radiator had anything to do with that?

 

[W5LZ]

"So an inefficient antenna will have more gain than a efficient one?

When efficiency goes up what does gain do?"

First, an inefficient antenna can have more gain than a more efficient antenna. That's a fairly common occurrence.

Secondly, when efficiency goes up, nothing happens to gain.

The thing is to define 'gain'. The commonly accepted definition of gain has nothing to do with efficiency of the antenna.

All 1/4 wave length antennas will have less gain than a 1/2 wave length antenna designed for the same frequency. That certainly does not mean that the 1/4 wave length antenna is less efficient than the 1/2 wave length antenna!

Equating efficiency and gain is like comparing apples and oranges. Big differences between them.
- 'Doc

 

[Marconi]

nice posty henry,

regardless of eznec indicating about the same gain as a 5/8wave or not there is more than the 1db advantage over a 5/8wave ground plane that avanti claim when we compare a 5/8wave to a vector 4000 tuned for maximum signal in this area, something is causing this effect

Bob, I've fiddled with my version of the Sigma 4 model to get the measurements and elements tapered per the specs. I also have a feed line and a mast in the model. The radials are only one element each instead of two tapered sections, and the segments in the radiator and the radials are the same number and size between wire #2 and the radial wires 43-45. I did tweak the tip of the radiator a bit to set the antenna resonance at the design frequency of 27.185, but I have no matcher and the resistance is rather low around about 18-25 ohms, about the same as a 1/4 wave with horizontal radials.

I also made a model of the I-10K, and I think I did the same with all elements, true to size and diameter, including taper, just like my antenna set at 27.205 mhz. Again I did not include matching and that antenna is not resonant and neither resistance or reactance is close.

Here are the results. The gain and angle for the Sigma4 shows 4.92 dbi @ 7* degrees and the results for the I-10K shows 3.71 dbi @ 8* degrees with a 1.21 dbi difference.

Is the gain and angle here about what you might expect the difference to be?

After I get through with testing my New Top One I just received, I hope to mount my Sigma4 as a final test in this series.

The total of all averages in this series thus far / # of tests for each antenna:

66.5/9 = 7.4 Gain Master
28.4/4 = 7.1 AstroPlane
21.9/3 = 7.3 A99
7.3/1 = 7.3 I-10K
7.1/1 = 7.1 Imax

Only the Top One's 4 tests were done at different heights and they were all included in this series. All antennas tested were switched between the two mounts. The antennas were tested together using a switch box, and then with them standing alone...with no other antenna around. Only exception was the I-10K, it was tested once in the same position near the shack on my new mounting position.

Since I now have a New Top One, I'll do the same with it as well and add those results to the recap above. I will also test at several different heights for the little short radiator on the AP and will including mounting it at the same base height at the GM. I hope I can figure out how to get a 4' foot section added to my pushup pole or the bottom of the NTO that is nice and steady.

Then maybe the Sigma4. Hopefully I won't have to tune that thing again. It is hard for me to tune with my setup here...working from a ladder. I use to have a patio cover about 12' feet high with a nice solid roof and I worked up there at about 15' feet and tuning went nicely, but now it is hard to reach that big old long gamma at both ends.

The only antennas I will not be including will be my Wolf .64, and the Wolf 50_11M which is broken. I can't figure out for sure where the bottom is on the .64 based on the manual provided. I remember talking to Eddie some while back about that, but I did not make any notes that I can find and I can't remember. Mack said he used the very bottom including the mount as the point to measure from. The manual suggests the bottom is the vertical element, and else where Eddie describes a center bolt in the mount at the bottom where the vertical element bottoms out in the mount. So, I suspect the length may be best measured from that bolt, but I'm just not sure.

I didn't want to spend time trying to figure that one out, because when I last took it down the match show a high SWR and I never figured out why. It may have been water in the gamma. Based on Mac's words I checked the other day and the top end of the gamma is not plugged up like he said, and rain can go right in with no obvious way out. So, I'm not messin' with that one this time.