Modified Vector 4000

[bob85]

Eddie
freespace has nothing to do with Henry's model with & without radials,
his chart shows the sigma with radials is stronger at 30 kilometers than the sigma without radials,

The larger the negative dbm number on the left of Henry's chart the weaker the signal is,

i get -89.7dbm without radials & -90.2dbm with the radials, .5db loss with the radials,

its not a new way of measuring signal strength, s-meters have never been a way of measuring anything,

they are just a relative indicator, they use the rigs agc line voltage to indicate signal strength,
they should be calibrated @ -73dbm or 50 microvolts for s-9 @ 6db per s-unit,

above 30mhz meters are calibrated @ -93dbm or 5 microvolts for s-9 @ 6db per s-unit

or that's how it should be but i never saw a radio that was 6db/s-unit, closest i have seen is my jrc @ 3db/s-unit,
half a s-unit increase on a radio meter just means the meter moved, its not measuring in any calibrated units
your half a pound could be 2 or 3 times my half pound increase,

the rsp1a has 4 calibrated s-meters,
one of the meters is the dbm meter scaled from -140dbm to -20dbm,

think of it as a very low power watt meter that measures voltage across 50ohms @ the antenna socket in the nanowatt, picowatt, femtowatt & attowatt ranges & displays the wattage relative to 1mw in -dbm or -decibel milliwatts.

the higher the negative number the weaker the signal
look at the charts in this thread
https://www.sdrplay.com/community/viewtopic.php?t=3582

 

[The DB]

I do remember Henry giving The DB a caution in his application of this feature in his modeling with 4NEC2 back around the time you posted Henry's report. However, I do not know if they discussed the idea further. Those 2 are the only folks I've ever heard discuss whatever this signal measurement feature is called.

Back when Henry released that report, there were two separate discussion we had relating to freespace. I am not sure which one if either is being referred to, so I will give a brief overview of both.

The first has to do with AGT or average gain test. The discussion was weather running AGT in freespace and over a perfect ground would net the same results. This was more a question of how the software handled the two environments, and as it turns out, it doesn't matter as both environments will yield the same results. One thing to add on this is I know 4nec2 manually removes any form of loss before running AGT, rather than letting the nec2 engine do it on its own. I don't know if this is just being thorough, or if the nec2 engine that 4nec2 uses doesn't always remove said losses on its own, which is necessary for AGT to run properly.

The other discussion had to do with angles of radiation in freespace vs over an earth, and what situations they apply to in reality. It was freespace models that I used to confirm bob85's real world "steering" RF towards the horizon results in modeling. This is something that could not be done if modeled over an earth.

EDIT: I originally wrote the text "two examples" in the above paragraph but only included one. I have a second example, but it may cause more problems than its worth so I removed it.

There is a third discussion that I think may be relevant to what has been posted here that I had with Henry at the time as well. It had to do with using 4nec2 and its ability to give dBm measurements at a given point in space around the antenna. I later found this method to be inaccurate, and since finding this out I have discarded this as a means of measurement.



The DB

 

[Marconi]

Thanks DB, I have some recollections of what you're telling us.

The first has to do with AGT or average gain test. The discussion was weather running AGT in freespace and over a perfect ground would net the same results. This was more a question of how the software handled the two environments, and as it turns out, it doesn't matter as both environments will yield the same results. One thing to add on this is I know 4nec2 manually removes any form of loss before running AGT, rather than letting the nec2 engine do it on its own. I don't know if this is just being thorough, or if the nec2 engine that 4nec2 uses doesn't always remove said losses on its own, which is necessary for AGT to run properly.

On this issue I remember asking you, "...if we could apply the Average Gain (AG) error value to both the Free Space (FS) models and the Real Earth (RE) models"? I think we both agreed it is acceptable to use the error correction value to adjust the reported gain...that is otherwise - either overstated or understated.

There is a third discussion that I think may be relevant to what has been posted here that I had with Henry at the time as well. It had to do with using 4nec2 and its ability to give dBm measurements at a given point in space around the antenna. I later found this method to be inaccurate, and since finding this out I have discarded this as a means of measurement.

DB, this is the topic I was curious to see Bob describe more about, using his technique for measuring in dbm.

I recounted what I recalled of the dbm issue several years ago, soon after Bob published Henry's report. I don't remember much, but I saw for the 1st time the idea Henry presented on page #41, and I likely got some things wrong in my recent response to Bob. I should have continued to ask questions about that idea, but I was in trouble already for asking questions and giving my opinions at the time. For a reference, see "Room for Improvements" section of this report.

Db, can you tell us a little about what you later found out was the reason for making those results in 4NEC2 inaccurate?

Does this also suggest that Henry's presentation, in that particular case was likewise inaccurate?

Frankly I did not understand what the chart in Henry's report was showing us on page #41. I also recall that Henry did not respond to my question...instead saying something like, "...that idea was misunderstood,." and my posting that question on the forum...just got me into more trouble at the time.

DB just in case an explanation is uncalled-for at this point, did you ever model a Vector with 4 x 109" horizontal radials positioned right below the Feed Point?

If so, what kind of "regular modeling" performance results did you get comparing these 2 design ideas?

EDIT:
I noticed that the image of Henry's manual page #41 did not show up good. Here is the link to his report which is on page #41 of #43 pages. Use the elevator at the top left of the PDF file.

https://cb-antennas.com/wp-content/uploads/2013/12/Sigma-IV-1.01-Jan-2015.pdf

 

[Marconi]

Here are 2 video examples regarding the differences between dbm and db. Most of the nitty-gritty is within the first minute or two.

https://www.bing.com/videos/search?q=dbm+-90.2+vs.+89.7+=&&view=detail&mid=CAA742E81F5E08EB0A33CAA742E81F5E08EB0A33&rvsmid=491CC424BAF1CCEF557B491CC424BAF1CCEF557B&FORM=VDQVAP

https://www.bing.com/videos/search?q=dbm+-90.2+vs.+89.7+=&docid=608029380901014806&mid=491CC424BAF1CCEF557B491CC424BAF1CCEF557B&view=detail&FORM=VIRE

 

[The DB]

On this issue I remember asking you, "...if we could apply the Average Gain (AG) error value to both the Free Space (FS) models and the Real Earth (RE) models"? I think we both agreed it is acceptable to use the error correction value to adjust the reported gain...that is otherwise - either overstated or understated.

You can not use AGT over real earth, but you can use perfect ground. When running AGT it needs to use either free space or perfect ground, anything else will not be lossless, and therefore will give a bad AGT result. 4nec2 does this check for me, if there is a ground present, any ground, 4nec2 will substitute a perfect ground. I can't speak to EZnec on this, thats your department.

DB, this is the topic I was curious to see Bob describe more about, using his technique for measuring in dbm.

Bob85 isn't the only person who uses dBm when it comes to measuring antennas. For nearly a year now my preferred way of tuning antennas uses dBm readouts from a portable spectrum analyzer. Its no different than how I used to use field strength, only now I have specific measurements rather than a relative number that I could adjust with a variable resistor. The setup is nothing fancy, its just a portable antenna mounted far enough out with a coax running to a spectrum analyzer that is plugged into my laptop. This one requires a laptop as my spectrum analyzer has no built in screen. I am effectively tuning the antennas by measuring performance directly.

I recounted what I recalled of the dbm issue several years ago, soon after Bob published Henry's report. I don't remember much, but I saw for the 1st time the idea Henry presented on page #41, and I likely got some things wrong in my recent response to Bob. I should have continued to ask questions about that idea, but I was in trouble already for asking questions and giving my opinions at the time. For a reference, see "Room for Improvements" section of this report.

Db, can you tell us a little about what you later found out was the reason for making those results in 4NEC2 inaccurate?

Does this also suggest that Henry's presentation, in that particular case was likewise inaccurate?

When it comes to dBm and the 4nec2 modeling software, the results are in fact not accurate. The reason is how the angles form in models over an earth. Most people assume those angles form immediately at the antenna, or immediately after the near field collapses, but unless the antenna is mounted at earth level or immediately above said earth, this is an incorrect assumption. Unfortunately the 4Nec2 modeling software makes the same assumption. However, I can't speak to the EZnec pro software that Henry used, so I cannot say for sure weather or not his data is accurate or not.

Frankly I did not understand what the chart in Henry's report was showing us on page #41. I also recall that Henry did not respond to my question...instead saying something like, "...that idea was misunderstood,." and my posting that question on the forum...just got me into more trouble at the time.

DB just in case an explanation is uncalled-for at this point, did you ever model a Vector with 4 x 109" horizontal radials positioned right below the Feed Point?

If so, what kind of "regular modeling" performance results did you get comparing these 2 design ideas?

Henry's chart shows things differently than 4nec2 shows them Essentially, the numbers across the top are the height of the measurement in meters, while the numbers going up and down are the measurements of signal strength in dBm, and as these numbers are negative, the lower numbers are better. From two sentences above the graph it is stated that these measurements are from 30 Kilometers out from the antenna. I think the layout of this chart could have been made more intuitive than it is here.

I have not modeled a vector with horizontal radials in addition to the cone. In my view, the currents flowing the basket area of this antenna are necessary and required for this antenna to function as intended. Adding horizontal radials will cause currents to be divided between the cone and said horizontal radials, this will change (lessen) the currents on the cone, which will affect how the cone does the job it needs to do effectively (in your case I would say that this effects the cone's ability to cancel the the out of phase RF from the antenna within the cone). Is this desirable? To be honest, I haven't explored this idea, but conceptually to some extent you should be able to get away with it removing currents from the cone of this antenna, up to a point. I am not sure if adding four horizontal radials will get you to that point or not, but I am pretty sure they will get you awfully close. Mind you, this is mostly just ramblings of ideas from off the top of my head and not completely thought out, so at best the ideas in this paragraph should be explored more thoroughly...

Here are 2 video examples regarding the differences between dbm and db. Most of the nitty-gritty is within the first minute or two.

Long story short, when to see a dB or decibel figure, a decibel is always in comparison to something else. dBi is decibels compared to a theoretical isotropic radiator in freespace, dBd is decibels compared to a center fed half wavelength dipole mounted in freespace, dBq is decibels compared to a 1/4 wavelength ground plane antenna with four horizontal radials in freespace, dBm is decibels compared to 1 milliwatt of power. You can't have just 5 dB gain, or the 9.9 dB gain as the a99 claims. A decibel always have to have a point of reference or comparison. As there is no assumed reference when it comes to decibels, if you do not specifically state a reference or comparison like I did with the examples above, or dB gain over x antenna, or something like that then the number you give in meaningless, and is in fact not technically a decibel, even if you say the word.


The DB

 

[Marconi]

You can't have just 5 dB gain, or the 9.9 dB gain as the a99 claims.

DB, do you know who published this news worthy idea about 9.9 db gain?

I like my relative reading SWR/Signal meter on my radios and it is good enough for me. I prefer a meter with a real needle though.

I haven't found anything in two-way-radio yet that requires me to understand all these little details on the workings and I still think all of the CB vertical antennas I've ever used, within reason...performed about the same, if I get the tips at or near the same height.

Do you guys think we can come up with some more opinions and big words to make another thread with 1000's of views?

 

[The DB]

DB, do you know who published this news worthy idea about 9.9 db gain?

That would be Antron back in the day, I'm guessing the marketing department.

I like my relative reading SWR/Signal meter on my radios and it is good enough for me. I prefer a meter with a real needle though.

For just tuning antennas, that is fine, and I have no problem with your preferences. However, with a spectrum analyzer, I can get into things you likely don't care about, such as checking for how bad the harmonics of a radio are, checking the bandwidth of the transmitted signal to make sure it isn't splattering up and down the band, and even more. In the end you don't have to do things as I do, you do you.

I haven't found anything in two-way-radio yet that requires me to understand all these little details on the workings and I still think all of the CB vertical antennas I've ever used, within reason...performed about the same, if I get the tips at or near the same height.

I agree with this statement, and I am aware that this is enough for you. Does this mean I have to limit myself to these standards as well? That being said, I'm not buying this. If you are happy with this level of understanding, why do you spend so much time on said high level discussions? Which one is it?

Do you guys think we can come up with some more opinions and big words to make another thread with 1000's of views?

I entered this discussion because my name was mentioned in reference to a prior discussion. I posted in reference to what said prior was about, more of a clarification and reference for those who weren't here or don't remember them. I was then asked questions and for answering those questions this is what I get?

Big words huh? Did you even bother to read my post? I went through great pains to explain things as simply as I could. This is something I always do on forums like this as I want people to understand what I am saying. Further, I didn't go beyond any knowledge that you haven't previously demonstrated you have or are capable of understanding.

I don't hate you Marconi, but its bs like this that I find frustrating. Its partly why I haven't posted so much in your recent discussions with bob85. When you pull bs like this it ends up being not worth my time...

In the future, if your going to come out with a response like this, perhaps you shouldn't ask the questions in the first place....


The DB

 

[bob85]

Since we are talking about the effects of adding radials & Henry's graph of signal strength @30km with & without radials at different heights above ground shows the difference in decibels I used the same scale in my test measurements

I could have said about one twelfth of an s-unit but what would that mean?

My s-units are 6db/s-unit & s-9 is 50uv or-73dbm, radio meters are nothing even close to that,

imagine the world of shit we would be in if everybody had their own scales on volt & amp meters,

if I had said about s-9 with the radials & a needlewidth increase when I remove the radials,
how do we equate that to anything, how does that compare to s9 on your rig & how do you determine 1/12 of a s-unit on a bar graph,

what I posted tells DB or anybody else that uses or understands dbm not only how many db change I see under the conditions of the test but how strong the signals were relative to 1mw,
I don't know of any other way to do it than use the same units as everybody else,

IM not claiming my sdr is as accurate as DB's specan, its probably no more accurate than my old ep300 field strength meter that also measures in dB for ratio measurements,
or dBm, dBμV, dBmV, V for level & power measurements,

there are no s-units on field strength meters,
rig s-meters are just a relative indicator even if you calibrate s-9 @ -73dbm 50uv with a calibrated sig gen,
the rest of the meter scale is meaningless with regards to quantifying a signal level or change in signal level,

If you want to measure something & share the results with other folk & it mean anything you should be using commonly used & even more importantly quantifiable units of measurement,

Me Henry & DB are using the same units of measurement.

 

[Marconi]

Bob and DB, I can't argue the merits of such testing, but I think I know a little more about what your trying to explain now that we're talking about these ideas.

I think this forum is lucky to have folks like you, DB, and others...that get into the nitty-gritty of the more technical side of this hobby.

By the way, I got a Happy New Years card from Master Chief and I invited him to rejoin the old group...and I also told him we are still fussin' and discussin' about antennas of all kinds.

By the way I think I have finally finished getting the I-10K model to working close to right. And, I have a new idea for how it works better than most...at least on paper, and these results might make you want to throw spit balls at the old Avanti Saturn you have in moth balls.

Plus you don't need to use two coax feed lines.

i still have to figure out what makes it better and how to tweak its advantage over others, with maybe 1 or 2 exceptions.

I think I can show & tell how it works, but I'm trying to figure out how best to just use words...and tell those interested...that it works.

 

[The DB]

Master Chief? I know the name but can't place it.

Doing some research, his last post was from two years before I started posting here, which explains that. He also accessed this forum yesterday so he may pop his head back in... I likely know him more from either old posts I have read through, or some other forums he may have posted on since then.

One way to explain dBm measurements, think of it like an s-meter on a radio, only far more accurate. Another way of describing it is like an advanced field strength meter that has two benefits over a normal field strength meter. One is instead of a random distance on an analog display, which can change with power level being measured, it gives specific readings. The other is it separates out the signals received on the various frequencies, so unless someone is on the exact same frequency, another person transmitting nearby won't effect your readings.

It has been a while since I played with an I-10k model. I'm curious as to what you found that is new with that antenna...


The DB

 

[Marconi]

It has been a while since I played with an I-10k model. I'm curious as to what you found that is new with that antenna...

DB, here is the model. I said it was a new idea, but I've posted about the considerable dual polarity this antenna looks to produce. I believe this might be an advantage, at least when DX is working and it really worked well in some WWDX contests back then.

Back in the days, probably about when Bob got his I-10K , we discussed the tuning. I think we both had a similar issue that we called a "Split" in the match, for lack of a better description. I talked to Jay about this issue and he sent me some tuning workup that he had done in some graphs. Maybe Bob remembers our collaboration back then.

What I see here is an antenna that produces a lot of currents around the trombone tuner and it is in the horizontal position in the Antenna view. We can also see this effects of the pushing up in the patterns too. I think this is all likely due to the large tuner used in the design.

 

[The DB]

Its not surprising, I've found many matching circuits like this carry high currents, always much higher than the parts of the antenna nearby. I've seen some matching circuits that exceed the current node of the antenna when it comes to current flow. I haven't noticed much of a difference when it comes to performance so this current flow normally doesn't affect the radiation pattern of the rest of the antenna to much.

I also remember reading about someone else noticing that this antenna design has a significantly higher than expected horizontal component, I think this was from before I started modeling. In any case, you may be on to something. When looking at the design of the matching circuit with this in mind it is definitely plausible.


The DB

 

[Marconi]

DB and Bob, I just now read both of your last posts from yesterday. And, apparently I said something earlier that concerned you both.

Some of what I have to deal with folks. Since my bout with Covid I've been, more or less, working the grave-yard shift, so-to-speak.

Of late, I mostly do my thing on the computer in the early AM. And, during the daylight hours, I'm in-an-out-of-the-bed...when I punk-out, and I can't function with a clear head and have ZERO energy.

My only interest is to get both of you talking about this topic, dbm measurements, that Henry presented to us back in 2014. I would also like to hear more from Henry on this topic.

You can not use AGT over real earth, but you can use perfect ground. When running AGT it needs to use either free space or perfect ground, anything else will not be lossless, and therefore will give a bad AGT result. 4nec2 does this check for me, if there is a ground present, any ground, 4nec2 will substitute a perfect ground. I can't speak to EZnec on this, thats your department.

DB, I think you misunderstood the point I tried to make in my question to you a while back...when I asked you the following. To be clear, I'm not sure about my actual words to you back then, but this is what I meant. Maybe I'll paraphrase a bit.

"Can we use the error value we get when running the AG test, and apply that error value to the reported gain for the Real Earth model to correct the overstated or understated gain reported?

DB the question was not about, when we can run the Average Gain Test, or whether the AGT runs automatically, or do I have to flip the switch manually using Eznec.

That would be Antron back in the day, I'm guessing the marketing department.

This question was not a dig to your understanding DB. I've seen the same claim on W8JI's Website, and you've seen it noted in the A99 manual that Solacon publishes. In both cases they are talking about a horizontal 1/2 wave antenna. I feel like this distinction should be made clear in the CB Antenna Section. No doubt, both of these comments are likely from the advertising departments for these folks.

Click here: https://www.w8ji.com/antennas.htm

I agree with this statement, and I am aware that this is enough for you. Does this mean I have to limit myself to these standards as well? That being said, I'm not buying this. If you are happy with this level of understanding, why do you spend so much time on said high level discussions? Which one is it?

DB, I don't think either of us would encourage others to limit their understanding on any issue. I think this dbm issue is complicated. I still have questions with varying to no answers, after 7 years, when Henry dropped the idea on us in his reveling report on the "Avanti Sigma 4," showing us what it does and how it works.

Me Henry & DB are using the same units of measurement.

Bob said it, so I say, "...who better to ask questions about these ideas." Some of us CB operators are probably interested in better ways of comparing our CB antennas and the signals they make.

 

[Marconi]

Bob, how would you compare your DX work using your GainMaster, AstroPlan, and I10K?

Have you used your dbm testing ideas on these antennas?

If so, can you give us your results?

 

[bob85]

Eddie,

i had no idea that you did not understand what Henry's graph was showing,
i don't know how it was generated other than its a function of the software Henry uses,

we talked about s-meters in the past & why radio meters are not calibrated & how some rigs at certain spots across the s-meter scale show significantly more of a change in signal than other radios,
somebody posted swizzradio's mod to change the response by changing a silicon diode to a germanium diode,

i have 4 ways to measure signal strength for antenna tests in calibrated units,
only one of them has s-units & they are not the same as your s-units,

rsp1a,
dBm or s-units @ 6db/s-unit -73dBm for s9 below 30mhz,
6db/s-unit -93dBm for s9 above 30mhz,
Unaohm ep-300,
dBm, dBμV, dBmV, V

lp-100 vector watt meter,
dBm

pc dso/spectrum analyzer,
dBm up to 32mhz.

if you are not looking for lab accuracy but want to use quantifiable units with much higher accuracy & resolution than a cb or ham radio meter you can get into measuring dbm and calibrated s-units with a sdr dongle.