Is the Solarcon Max2000 5/8th di-pole like ?

[RadioDaze2.0]

Well I mention it casually thinking the book is a source that can be trusted. I don't know if it can ?

I take asymmetry to mean non symmetrical arrangement around the radiator base and/ or different lengths of radial causing current imbalances.

Nothing to test here for me I won;t be putting radials on due to the massive inconvenience. The only thing like any type of radial is earthing my poles to a fence 3 feet from the ground. And as we know this is far to far from the antenna to count as a ground radial of any sort we are normally familiar with.

However it may influence the radiation pattern in unknown ways given anything in the reactive near field can.

Just casual commentary on my behalf really.

 

[Needle Bender]

Hmmm, giving more thought to the Imax2000 performance increase when downward diagonal radials were added plus The DB's mention of out-of-phase current and Marconi's mention of CMC along with the common knowledge of the Imax using the coax for the counterpioise...
- I wonder if what's happening to add apparent gain to my Imax, (locally) is simply a decoupling of the CMC by adding a resonant 1/4 wave counterpoise thus removing the opposing current from the coax and moving it upward toward the horizontal?
- Though the 'radial' pointing in the direction of the receiving S-meter was rather steep, 16 feet from the mast, 32' below it, - making it a rather steep 67°, still, the decoupling effect should be intact.

Marconi, I seem to recall you may have plotted an Imax with & without radials, but have you compared all four angles to see TOA changes, adding 4 full 1/4 wave radials at a downward diagonal angle, comparing true horizontal to 30°, 45°, 67° & full vertical downward (as in using the coax) ?

 

[Marconi]

Hmmm, giving more thought to the Imax2000 performance increase when downward diagonal radials were added plus The DB's mention of out-of-phase current and Marconi's mention of CMC along with the common knowledge of the Imax using the coax for the counterpioise...

NB, over time I have come to believe what 'Doc use to always tell us regarding comparison testing of our antennas in our backyards. There are just too many variables in the real world to reach a definitive conclusion...and for sure if the testing is between your antenna and a buddy down the road. I believe you see what you report, but IMO that is likely not as reliable as the numbers might show. I can say I never saw a big difference among my CB antennas...unless maybe when the antennas were mounted at the same height to the feed point and comparing a 1/4 wave or shorter to a 3/4 wave antenna.

- I wonder if what's happening to add apparent gain to my Imax, (locally) is simply a decoupling of the CMC by adding a resonant 1/4 wave counterpoise thus removing the opposing current from the coax and moving it upward toward the horizontal?

In all of my models for the Imax, and maybe for all of my 5/8 wave antennas...the maximum currents indicated on the coax and/or mast primarily show to be constructive and in phase with the top 1/2 wave portion of the radiator, but it is hard for me to tell what angle is benefited.

On some of my other antenna models...they do not always show the same positive-type results with the radiation on the mast like this Imax model does. In fact, when I'm able to eliminate these out of phase currents on the mast I think the antenna gain results tends to drop some...even though the antenna looks to have been improved.

NB, like you suggest here, in the past it has been suggested to me...that if we can stop the currents on the mast/feed line these currents will then flow on the radiator, and thus add to the maximum radiation for the antenna. I wish I knew what actually happens in these cases. I just don't see this happening with my models.

- Though the 'radial' pointing in the direction of the receiving S-meter was rather steep, 16 feet from the mast, 32' below it, - making it a rather steep 67°, still, the decoupling effect should be intact.

I don't understand what you are trying to describe here.

Marconi, I seem to recall you may have plotted an Imax with & without radials, but have you compared all four angles to see TOA changes, adding 4 full 1/4 wave radials at a downward diagonal angle, comparing true horizontal to 30°, 45°, 67° & full vertical downward (as in using the coax) ?

I have done some similar modeling work at various angles like you described. However, I still don't see much difference with a 5/8 wave antenna...even in the match, comparing horizontal radials to various slanted down radials on the Imax. I decided to do my old work over just to be sure...at the specific angles you describe.

I used an Imax model that has 6' foot radials however, and I know you will object to that probably, so I did a model like the first with horizontal radials using 9' foot radials.

The models still don't show the difference I think you are suggesting in your ideas above.

Thus far I have 6 variations of models and that is a lot of work to post. Let me figure out how I should proceed.

Below are two of the Imax models plus an overlay of the antenna patterns showing max angles and gain.

The 1st model is with 6' foot radials and the second is with 9' foot radials with the mast isolated (ISO) from the antenna at the feed point just to see if there is much difference due to isolation.

 

[The DB]

In all of my models for the Imax, and maybe for all of my 5/8 wave antennas...the maximum currents indicated on the coax and/or mast primarily show to be constructive and in phase with the top 1/2 wave portion of the radiator, but it is hard for me to tell what angle is benefited.

Seriously? Ok, how about this one, a 5/8 wavelegnth, with no radials, and a single 1/4 wavelength section below the antenna simulating putting a choke 1/4 wavelength down the coax from the antenna. The mast is isolated...

The top half wavelength is a given phase. The remaining part of the 5/8 wavelength element is out of phase, as expected. As you pass the feed point onto the lower element, the phase does not change, thus the area immediately below the feed point on a vertical 5/8 wavelength antenna, will always be out of phase with the upper part of the antenna no matter how long that feed line/mast are. The best you can do is to manipulate the length of said wire to put a phase change right next to the feed point of the antenna.


The DB

 

[Marconi]

In all of my models for the Imax, and maybe for all of my 5/8 wave antennas...the maximum currents indicated on the coax and/or mast primarily shows to be constructive and in phase with the top 1/2 wave portion of the radiator, but it is hard for me to tell what angle is benefited.

I realize the top portion of the mast below and near the feed point is out of phase just like you suggest. My model shows this 1/4 wavelength too. I was referring to the primary section of currents on the mast that is a 1/2 wavelength...and as noted in the exaggerated antenna view attached below.

IMO, the lobe I marked radiates constructively with the top 1/2 wave of the radiator. I am not suggesting this lobe makes much radiation or that one can expect it to be a detectable advantage however.

On the contrary my Sigma 4 model shows the opposite mast/coax radiation. See the 2nd exaggerated image of the S4 attached below...the current is on the opposite side of the image just as I mentioned earlier. I could had described myself better.

 

[Needle Bender]

Hi Marconi,

What I had going on were diagonal downward 1/4 wave radials made from guy wire, attached to the top U-bolt, down 9' to an insulator then parachute cord the rest of the way, so they are/were not in the horizontal, but downward/ diagonal.

The one in the direction of the S-Meter where I saw gain was the steepest & was attached to a guy point on the roof 16' away from the mast and 32' below where it attached to the mast, making it a rather steep downward diagonal angle of about 67°.

And in your sim it's quite interesting how the non-resonant 6' Horiz radials beat the 9', 1/4 wave Horiz radials on the Imax2000 for low TOA energy.

Here's one for you, (just for 'grits & shins') how about 4 horiz 1/4 wave radials at the bottom of the NV4K?

 

[The DB]

Eddie, on your 5/8 wavelength with radials antenna you are pointing to a 1/2 wavelength of in phase current, however, you are not saying anything about two out of phase sections, one of which is 1/4 wavelength, and the other is some additional amount. A question to ponder, are these out of phase portions of the element enough to have a detrimental effect on the antenna as a whole?


The DB

 

[Marconi]

Eddie, on your 5/8 wavelength with radials antenna you are pointing to a 1/2 wavelength of in phase current, however, you are not saying anything about two out of phase sections, one of which is 1/4 wavelength, and the other is some additional amount. A question to ponder, are these out of phase portions of the element enough to have a detrimental effect on the antenna as a whole?

The DB

DB, I don't know how the currents on the mast/coax in this case effects the antenna. I mentioned this earlier. I was only calling attention to our seeing the maximum primary radiating portion, the 1/2 wave section, as being in phase on the Imax model.

Over time I have had antennas that acted bad with what I thought were currents on the mast/coax, but I never observed this to make the antenna any less effective...just using my radio, and I don't see it in modeling either.

My point in all of this, concerns the claims we often hear that states...if we can minimize or eliminate these currents on the mast/coax, these same currents will then be redirected onto the antenna and thus increase the gain.

My models don't show any noteworthy gain when I isolate the mast and minimize or stop the CM type currents flowing on the mast/coax DB. I don't know how to do this with Eznec using the choke feature. Maybe you can help me out.

Can you show us what happens with the gain on the model you posted above, before and after you add the choke?

 

[bob85]

Eddie,
I have not heard the claim that removing cmc from the mast/coax causes those currents to be redirected to the radiator increasing gain,

Whatever current leaves the coax centre conductor and flows into the radiator must be returned on something so it can flow back on the inside of the shield,
that something could be anything and everything connected to the coax braid at the feedpoint including the outside surface of the coax shield sharing return currents,

removing current from mast & coax with a choke and mast isolation forces more return current to flow into whatever is connected to the coax braid above the isolation point as per Kirchhoff's current law,

if there is nothing or insufficient material above the choke for return currents the choke won't work,

you are redirecting return currents but not to the radiator increasing gain,

any improvement in signal is imho due to not allowing currents that spoil the pattern to radiate on the mast or coax forcing return current to flow on something that won't spoil the pattern like horizontal radials or beneficial in the case of a stardusters drooping radials.

 

[The DB]

Can you show us what happens with the gain on the model you posted above, before and after you add the choke?

First off, you are not actually doing what you are asking of me yourself.

Take these models for example...

The plots on the left the antennas are mounted 6 meters above moderate ground, the plots on the right the antennas are mounted 11 meters above moderate ground. All antennas are 5/8 wavelength antennas.

cmctest1 and cmctest2 (the green lines) are nothing but the 5/8 wavelength vertical elements. There are no radials, and no mast/feedline. They are essentially the optimal installation for said antennas, and can be seen as the goal to shoot for.

cmctest1b and cmctest2b (the red lines) are the same antennas with a mast that directly connects to the earth below. There are still no radials in play here. These models simulate what an Imax would do if put on top of a mast with no form of CMC control.

cmctest1c and cmctest2c (the blue lines) are the same as the "b" models except they include radials.

If your models that include radials are the bases for your comparison between CMC present and CMC choked antennas then your comparison is flawed from the start as radials are, in and of themselves, a very effective CMC choke.

As for your request, a comparison of gain from the model I posted above compared to itself with a choke added, in this case the choke is made up of simply adding four 1/4 wavelength horizontal radials.

The DB

 

[M0GVZ]

Fractions of a S point between best and worst with a lowering of the take off angle of the main lobe, all so little as to make no significant difference and certainly not enough on their own to justify some of the claims being made as to X antenna being magically better than Y when it comes to monopole vertical antennas.

The only real difference which makes one commercially available monopole vertical worth buying over another is the mechanical construction. Any other claims made are effectively people buying into the marketing or people trying to convince themselves they've not just wasted $100 to find their new "Mega Super Gainer Signal Blaster 2000" performs effectively the same as their $20 halfwave did.

 

[The DB]

removing current from mast & coax with a choke and mast isolation forces more return current to flow into whatever is connected to the coax braid above the isolation point as per Kirchhoff's current law

You have a misunderstanding of Kirchoff's Current Law as it applies to the feedpoint of antennas. You seem to think that the feed point is a single node and the two antenna elements are the connections to said node. However, the feedpoint of even the simplest of antennas does not have one node, but in fact two.

Take a center fed dipole that is fed with a balanced feed line. The current from one leg of the balanced feed line goes through one node and out to that element of the antenna. The current from the other leg goes through the other node, and into the other element of the antenna. In this case balance is achieved, but only because the source itself was in balance with regards to current to begin with. As you can see, if the source is in perfect balance, and there is nothing present such as a matching system, your attempt at implementing Kirchoff's Current Law appears to work. However...

Now lets change the balanced feed line to an unbalanced feed line, such as coax. Now we have a center conductor with has a given amount of current flowing on it, and the inside of the shield, which has some other amount of current flowing on it. This is possible because the feed line is not balanced, hence the term unbalanced feed line. In this case we have the current that is flowing on the center conductor that passes through one node and out onto one of the antenna elements. We also have the other current that was traveling on the inside of the coax shielding that travels through the other node to the other antenna element. As these currents were not equal to start with the currents flowing on the antenna elements will also be different, even though the antenna itself is a balanced design. This is why using a balun on such an antenna setup provides a benefit.

Now to show another example of where your implementation of Kirchoff's Current Law goes wrong, lets look at a 5/8 wavelength antenna matching system. This is the schematic of an Imax matching section.

With one exception (the one on the far left), every other black dot in this schematic is a node. Each node will have its own voltage and current at any given time. The voltage and current present at any node will be based not only on the source voltage/current from the feed line, but said effects of the neighboring components as well. You cannot treat this entire circuit as a single node, which is what you seem to be doing. You have to treat each point in the circuit as a separate node or the math that goes along with Kirchoff's Current Law (and Kirchoff's Voltage Law as well) simply doesn't work.

NOTE: (If this note seems confusing feel free to ignore it) The exception would be the wire that directly connects two black dots. This link has no components, so both sides of this link would be the same node. They are essentially the same point electrically. However, there is a caveat here as we are dealing with an RF signal, which is AC, not DC. Because of this, if there is a distance between the two sides of this connection, the two sides will be slightly out of phase with each other even if the difference is only slight. As such, depending on the design, this distance, should it exist, would cause the two points to be treated as separate nodes.

This is just one possible matching system, there are others that would be even more complex. You cannot simply ignore the feed line and its possible imballance as a current source and, should one exist, the components in a matching system, and assume that an antenna works as a single node for Kirchoff's Current Law. That is simply not how antenna feed points work. Unfortunately, every time I see someone refer to Kirchoff's Current Law, they make this very mistake.


The DB

 

[The DB]

Fractions of a S point between best and worst with a lowering of the take off angle of the main lobe, all so little as to make no significant difference and certainly not enough on their own to justify some of the claims being made as to X antenna being magically better than Y when it comes to monopole vertical antennas.

The only real difference which makes one commercially available monopole vertical worth buying over another is the mechanical construction. Any other claims made are effectively people buying into the marketing or people trying to convince themselves they've not just wasted $100 to find their new "Mega Super Gainer Signal Blaster 2000" performs effectively the same as their $20 halfwave did.

The 1 dB or so of difference based on the model that Eddie asked for is insignificant, I agree, however, on many actual s-meters this would be enough to show a difference. If you think all s-meters s-points are actually 6 dB apart you are gravely mistaken. There are many used for CB that said points are closer to 2 dB apart. Because of this, the difference between going from a 5/8 wavelength antenna with no radials (or other cmc control) to a 5/8 wavelength antenna with horizontal 1/4 wavelength radials is over 3 dB, and could easily be perceived as significant. In general, 3 dB is considered the minimum amount of change considered noticeably, which two instances of modifying a 5/8 wavelength antenna above have clearly demonstrated.


The DB

 

[M0GVZ]

The 1 dB or so of difference based on the model that Eddie asked for is insignificant, I agree, however, on many actual s-meters this would be enough to show a difference. If you think all s-meters s-points are actually 6 dB apart you are gravely mistaken. There are many used for CB that said points are closer to 2 dB apart. Because of this, the difference between going from a 5/8 wavelength antenna with no radials (or other cmc control) to a 5/8 wavelength antenna with horizontal 1/4 wavelength radials is over 3 dB, and could easily be perceived as significant. In general, 3 dB is considered the minimum amount of change considered noticeably, which two instances of modifying a 5/8 wavelength antenna above have clearly demonstrated.


The DB

So its a S point on a CB meter. 3dB isn't considered a considerable amount of change and you're going to suddenly find a signal that was just there in the noise being any easier to copy because it was 3dB higher. It'd need to be at least 6 and with the claims made where people say "it made signals in the noise easy to copy" more like 8-10 which simply isn't going to be happening anywhere on planet reality if the only change was the antenna.

I've been involved with setting up VHF repeaters and some of the Kenwood mobile radios we use have the option to display the signal strength in dB. You can watch it change 3dB and notice no change at all in the received audio, that is how insignificant 3dB is.

Now if we were talking CW its a bit of a different kettle of fish as a 3dB change around the level of the noise floor is enough to make copying easier to the point it could be a make or break difference for a contact but for voice it isn't and certainly not for SSB or AM.

 

[The DB]

So its a S point on a CB meter. 3dB isn't considered a considerable amount of change and you're going to suddenly find a signal that was just there in the noise being any easier to copy because it was 3dB higher. It'd need to be at least 6 and with the claims made where people say "it made signals in the noise easy to copy" more like 8-10 which simply isn't going to be happening anywhere on planet reality if the only change was the antenna.

I've been involved with setting up VHF repeaters and some of the Kenwood mobile radios we use have the option to display the signal strength in dB. You can watch it change 3dB and notice no change at all in the received audio, that is how insignificant 3dB is.

Now if we were talking CW its a bit of a different kettle of fish as a 3dB change around the level of the noise floor is enough to make copying easier to the point it could be a make or break difference for a contact but for voice it isn't and certainly not for SSB or AM.

Most if not all modern radios have an ALC circuit, which at the level of the noise floor will modify the readings of said s-meter, and anything based on said signal that the s-meter reads. At said noise floor, signals that are farther apart power wise will appear closer together on an s-meter (weather it is measured in s units or dBm) due to this circuit. Very powerful signals will have a similar effect. This is the same with ham radio and CB. The 3 dB difference being significant number I gave comes from before these circuits were widespread and commonplace. Said circuits allows the radio to process a much wider range of received signal strengths than before. Because of this, i will acknowledge that modern day equipment that it can take a larger change in signal to be noticed.

When it comes to the plots you made you categorical estimation based on gain and assumed it would be the same for all contacts. The truth of the matter is that for local communications said plot is wholly inadequate as a measure. This is a surface wave chart for one of the antennas above (the 5/8 with mast, both with and without radials to control CMC, mounted one wavelength high). The measurement is the strength of the RF wave front taken at a given distance from the antenna running at 100 watts of power, and from 0 to 11 meters high. This chart does not take into account any losses or gains that a receiving antenna at this location would also present, but is a direct measure of the signal strength available at this distance over a moderate earth.

249 nV/m is 0.249 μV/m, or just above s1 on what an s-meter would show if it received a signal of that strength. 430 nV/m is 0.43 μV/m, and just above s2 on what an s-meter would show if it received a signal of that strength. Because of this, an antenna at this distance and height would see almost 1 s-unit difference between said antennas with and without radials... That comes very close to your minimum number to notice a difference, and given not every possible real world variable is in play here, could easily end up exceeding your number. There have also been real world reports of people who made a similar change that actually exceed these results. That isn't to say everyone who adds radials to said antenna will notice the difference, every installation and location is different after all. All I'm saying is your categorical statement that no one can and will ever notice a difference from this change in any circumstances as going a bit far.

The higher the transmitting antenna is above the earth (in wavelengths) and/or the further the receiving station is away from the transmitting station, the bigger the received difference will be between antennas. Because of this, one far field gain calculation and angle comparrison, wile a useful calculation for one aspect of radio, namely skywave propagation, is irrelevant when discussing long distance local surface wave contacts, i.e. contacts from people at the edge of your local communications range.

When it comes to modulation types, I agree that CW would require the least amount of signal difference to be noticed, in order I would followed that with SSB, then AM, and finally FM, which requires the most bandwidth of all of these modulation types listed, and based on differences with how FM works, there would be no "audio fading" at all at low powers at all as it uses frequency variations instead of the amplitude variations that AM and SSB use to send its information. The 3 dB number I gave above comes from noticing a difference with older SSB radios.


The DB