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Marconi's new Gain Master with a matching network
- Thread starter Marconi
- Start date
The charges that you are getting hung up on, in and of themselves, are not what is important, charge induces current, it is the flow of that current in a 3d space that matters. The charge, in and of itself is irrelevant. Because of this, I don't like the terms "positive" and "negative" as they are being used here, this idea that "charge" is the limit of what matters.
It is possible for two opposing charges to induce currents that travel in the same direction in space. In a radiating antenna, or a feed line that doesn't, it is the direction of current flow in space, not the charges that created it, that determines what happens. This is what you are failing to comprehend.
The DB
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In this center-fed full-wave dipole or "doublet" as some prefer, if voltage leads current by 90°, then as the voltage to the left 1/2 wave leg is a half-wave from 90° at the feed point to 270° through 0° / 360° in the cycle, the right 1/2 wave leg will necessarily be from 90° to 270° through the 180° point in the cycle, which necessitates the current in each 1/2 wave leg to be the inverse, or "inverted" with relation to the other leg, current peaking at 0°/ 360° to the left, peaking at 180° to the right, or 180° out of phase.
This inverse-phase current per 1/2 wave side/leg, (relative to the opposite 1/2 wave side/leg) should produce cancellation, not gain.
Wrong.
You really want to believe as you do don't you. As long as you choose to hold yourself back I (we) cannot help you.
Wait, am I reading this right? Do you actually think that just because the change in voltage happens at a current peak on an antenna that the direction the current is flowing also changes at said current peak? That is what it sounds like you are saying. That is impossible for any number of reasons. You are the first person I have ever heard suggested anything like this. Out of phase current, like the voltage, changes polarity when it reaches its own null, not when the voltage reaches a null. I understand how you could make this mistake, out of phase voltage and currents isn't exactly electronics 101 material...
Let me explain this another way. Voltage will carry the same charge from one voltage null to the next voltage null. Likewise, current is flowing in the same direction from one current null to the next current null. The change in voltage does not immediately change the flow of current when it is out of phase with said voltage as you seem to think it does, current lagging voltage by 90° implies the effects of voltage aren't actually represented in current until 90° later. This 90° offset is very different than your assumed immediate change. You can't go half way with this, it is an all or nothing proposition.
Also, I never stated that the voltage leads the current, I just noted that on an antenna their peaks and nulls are 90 degrees out of phase, I didn't state which one leads and which one lags. However, you did correctly guess which one leads and which one lags in this case. This is true as long as we are working with antennas that don't loop back to themselves, like the quad that you mentioned in a previous post. In that case current leads voltage.
If you really want to have discussions at this level I do recommend one thing. Do some more research when it comes to the phase relationship between voltage and current.
Now on to the other part of what you implied in error...
We have the word dipole. The prefix "di" has a meaning. What does it mean? Get this... 2.
And the other word you used doublet, which starts with the word "double" which also means 2.
There is another word used to describe these antennas, bipole. The prefix "bi" also means 2. (I added this more for completeness sake.)
All three of these mean the same thing, and all three refer to the same thing, they are saying there are 2 poles. So why are you treating an antenna that has 2 poles like a monopole antenna in your description? Its right there in various names of the antenna, "2 poles" not "1 pole". Or do you really not know how this affects the antenna? I'm sorry if this came out the wrong way, I'm not trying to be insulting here, but this is something I really need to know before I continue this discussion with you.
The DB
NB
The 90 degree lag only applies at resonance.
Can you point us to the source of your "unconventional" ideas on current & voltage distribution.
All the respected sources i have looked at seem to say the opposite of what you claim.
You said its our opinion & you also posted links to a website that backs up your ideas. And some physics.
NO so far you have posted a link to an impossible current distribution on an antenna that was clearly not the electrical length it claimed to be,
and you talk some imaginary voltage & current physics ideas,
Center fed Dipoles of any length up to Full wave radiate without any out of phase currents,
Until you get that you are just wasting your grey matter imagining all sorts of nonesense when you could be learning the truth,
How anybody can be involved this deep in antenna threads for this long yet have voltage and current distribution in dipoles all wrong is truly amazing.
Understanding current distribution & phase & what causes coax to radiate or not radiate significant currents is vital to understanding models.
The 90 degree lag only applies at resonance.
Can you point us to the source of your "unconventional" ideas on current & voltage distribution.
All the respected sources i have looked at seem to say the opposite of what you claim.
You said its our opinion & you also posted links to a website that backs up your ideas. And some physics.
NO so far you have posted a link to an impossible current distribution on an antenna that was clearly not the electrical length it claimed to be,
and you talk some imaginary voltage & current physics ideas,
Center fed Dipoles of any length up to Full wave radiate without any out of phase currents,
Until you get that you are just wasting your grey matter imagining all sorts of nonesense when you could be learning the truth,
How anybody can be involved this deep in antenna threads for this long yet have voltage and current distribution in dipoles all wrong is truly amazing.
Understanding current distribution & phase & what causes coax to radiate or not radiate significant currents is vital to understanding models.
LoL, I liked that. I described a simple AC sine wave and you reply, "Wrong"
OK DB, I read your post several times but it simply sounds to me like you are talking your way all around the point but never really addressing it.
So, to recap:
1.) Voltage leads current by 90°. (Because it does whether or not you mention it.)
2.) Voltage is 180° out of phase between the left & right 1/2 wave halves of this full wavelength-long center-fed wire. (I refuse to call it an Antenna because an antenna should radiate.)
3.) An 1/2 wave current node is produced across two voltage points on each side or half of this center-fed full-wave length long wire.
4.) Each 1/2 wave of current is developed across two 180° out-of-phase voltage points.
5.) Each 1/2 wave of current is at a phase 90° behind the phase of it's voltage.
6.) The voltage on one side will flow from 90° to 270° through the 180° point in the sine wave,
- as
7.) The voltage on the other side flows from 270° to 90° through the 360° point in the sine wave.
8.) The current peaks at the voltage null, 1/2 way between the two voltage peaks.
9.) The current peak on one side will be at 180°
- as
10.) The current peak on the other side is at 360°.
11.) Therefore these two 1/2 waves of current are 180° out of phase.
12.) Out of phase currents cancel.
13.) The two 1/2 wave current nodes of this full-wave long center-fed wire should be out of phase and cancel each other, preventing efficient broadside radiation.
Bob you posted while I was writing my response to The DB.
I will need you to explain what is "Unconventional" about a sign wave consisting of 360° of voltage & current before I can formulate any intelligent response to your post.
Please simply ignore the earlier illustrations to which I posted links, they were merely to illustrate the shape of the sine wave of current being described and were not intended to illustrate artistic accuracy, feed types, design parameters, etc...
Unconventional = not how it is NB.
Its how you imagine it to be.
Current inside coax is ALWAYS equal magnitude & opposite phase.
Imaging current on one half cycle leaves the coax center conductor flows up the radiator,
Out of the radiator as displacement currents,
Along the shield leg
back down the coax.
Which direction relative to current on the radiator must current flow on the shield leg in order to satisfy the equal magnitude opposite phase rule inside the coax ?
If you want to make current on one leg be 180 degrees out of phase and cancel radiation you must fold the dipole
( reverse the direction of one leg in space relative to the other) so that the legs are parallel.
Anything other than parallel and closely spaced will have some radiation.
Its how you imagine it to be.
Current inside coax is ALWAYS equal magnitude & opposite phase.
Imaging current on one half cycle leaves the coax center conductor flows up the radiator,
Out of the radiator as displacement currents,
Along the shield leg
back down the coax.
Which direction relative to current on the radiator must current flow on the shield leg in order to satisfy the equal magnitude opposite phase rule inside the coax ?
If you want to make current on one leg be 180 degrees out of phase and cancel radiation you must fold the dipole
( reverse the direction of one leg in space relative to the other) so that the legs are parallel.
Anything other than parallel and closely spaced will have some radiation.
Well, that's what I was hoping, that I'm mistaken about this, because it would mean I could effectively increase my power by almost double on the 40m band just by tuning & using the balanced-fed 80m dipole,
- however,
2 years ago when I tuned it for 40m and checked with a few local & semi-local stations, they offered the same basic rst, averaging S7-8 where another local 6 miles away was in their red.
- But switching to the 40m 1/2 wave I was 10-15 over S9, just like my neighbor on his 1/2 wave dipole.
Bob, you're imagining that a full wave acts the same as a 1/2 wave dipole.
Walk one leg of a 1/2 wave dipole around?
Yes, from cancellation to radiation, however the same is not true for a full wave.
Bad logic, one is right, one is wrong.
- If I ram my truck into a brick wall I bend metal
therefore
if I ram a brick into a brick wall I must also bend metal, since they were both rammed into a brick wall.
- oops, guess they are two different things.
The voltage nodes at the ends of a 1/2 wave dipole create a single 1/2 wave of current between them which changes phase 180° every 1/2 wave. It has no 2nd 1/2 wave near it to cancel against.
When you double the wire length to a full wave dipole you now have two 1/2 waves in opposing phases which must necessarily cancel the other since they each charge the same basic air simultaneously but in opposing phases.
...but I wish it worked.
On this particular antenna design, yes, not on all of them.
Yes, voltage has two separate phases on each element, but that is irrelevant. It is the current that matters, not the voltage, and the current is in phase on the entire antenna. Your obsession of what voltage is doing is pointless, and leading you to the wrong answer.
A current node is in both halves of the antenna, yes, and in the case of the models above they are in phase. Truth. If they weren't, this antenna design that has been used by multiple times successfully would not have been.
Irrelevant, a current flow that is out of phase with voltage is not determined by local voltage that is out of phase with, but the voltage that leads it, so the current flow from voltage that it is leading is caused by 90 degrees is determined by the voltage 90 degrees away, not the voltage at that point. If it were, the almighty 5/8 wavelength antenna you so like would not, could not, work as it does. I think I stated above that it is possible that the voltage and the current can be 180 degrees out of phase with each other (I might have rewritten that part of the post), the reflected signal that is SWR is an example of this. With the way you think the phasing between voltage and current works this would be impossible.
You are right, but then you stated that in this post already, and I didn't disagree with.
No, it doesn't go all the way around, it goes half way around, and then it reverses course. If this were a monopole antenna rather than a full wavelength dipole you would be correct. You clearly don't understand the difference the feed point makes on this type of antenna, all you can see is one pole.
Yes, no argument from me.
Wrong, both sides are completely in phase. If it was as you claim, then not even the half wavelength dipole would work as by your definition they would be out of phase.
Wrong because feed point, the thing you don't seem to be able to comprehend. Both sides of the feed point are always in phase on a wire that runs straight out from either side of it.
Wrong, because the current isn't out of phase as you really want to believe. And even if it were the case, the antenna would still radiate, it would just not be broadside to the antenna, it would be more like an end fire design.
Wrong because feed point. You know, that thing that I wanted to make sure you knew the effects of on an antenna? You clearly don't. If things were as you claim, again, both sides would be out of phase for every center fed antenna design of one wavelength or less. Its an all or nothing thing, you cannot get by it, if that is what happens here, it is what happens on all of the antennas in this class.
In spite of the disagreement we are currently having, Merry Christmas.
The DB
Needle Bender, you wanted sources, right? I stated I don't like internet sources, so I will rely on some sources of my own.
Lets start with the book "Antenna Theory Analysis and Design" by Constantine A. Balanis, © 1982. This book, was written by a broadcast engineer for other broadcast engineers, and it was used as a textbook in some colleges to teach electrical engineers.
This is a scan from page 123. This shows the current phase for several lengths between a 1/4 wavelength antenna (full antenna length, not each side) and a 2 wavelength antenna. λ is the symbol for wavelength, for those that don't know. I outlined the pattern you should look for in red to make it easy to find...
As we can see by this image, which for some lengths of antenna does show there are out of phase currents, both sides of the 1 wavelength center fed dipole are completely in phase. This matches the models I and others posted above, and matches what I and others have been saying all along.
Lets move on, I have more for you...
From the book "antenna theory and design" by Robers S. Elliott, © 1981. (Yes, I didn't capitalize the name for a reason, on and inside the book it is also not capitalized). This is another book written by a broadcast engineer for other broadcast engineers, and also was used in colleges as a text book for teaching electrical engineers.
Anyway, I'm going to start this with a quote that starts with the last paragraph on page 58.
Then it continues on...
Now for Figure 2.2 they referred to.
Here, in the third pane, we have an example of current magnitude, with the arcs denoting magnitude, and the arrows representing current. We have, on both sides, a current peak (and the associated voltage null, not marked, however, according to this image this change in voltage does not cause current at the point to suddenly change like you insist it does. The current remains the same though this voltage phase change.
This isn't the only source I have that demonstrates this, I have a third for you that clearly shows, with a longer antenna than this, where the current's phase actually changes.
And the third source for today, from "Radio Antenna Engineering" by Edmond A. Laport, © 1952. This is another book written by a broadcast engineer for other broadcast engineers, and was (if not still is) the most quoted book on the subject of antennas. This book is available for free if you search for it online. We are going to start with text on page 256.
Figure 3.31...
Here, the middle image, or B, is the one that is relevant to our discussion, again we have a full wavelength center fed dipole, and as we can see from the arrows present, all of the current is traveling in the same direction, or is in phase. What does it take to get out of phase currents? An example is conveniently presented here for us with the right most image, or C. On C we have a center fed dipole with two 5/8 wavelength sides, giving us a full 1½ wavelength of antenna length. This clearly shows that the current phase does not change until the current null, it isn't the voltage null that changes the current's phase, it is the current null.
There is something else Fig. 3.31 clearly demonstrates, on all of these antennas there is radiation...
I can continue, but I think this is enough for now.
The DB
Lets start with the book "Antenna Theory Analysis and Design" by Constantine A. Balanis, © 1982. This book, was written by a broadcast engineer for other broadcast engineers, and it was used as a textbook in some colleges to teach electrical engineers.
This is a scan from page 123. This shows the current phase for several lengths between a 1/4 wavelength antenna (full antenna length, not each side) and a 2 wavelength antenna. λ is the symbol for wavelength, for those that don't know. I outlined the pattern you should look for in red to make it easy to find...
As we can see by this image, which for some lengths of antenna does show there are out of phase currents, both sides of the 1 wavelength center fed dipole are completely in phase. This matches the models I and others posted above, and matches what I and others have been saying all along.
Lets move on, I have more for you...
From the book "antenna theory and design" by Robers S. Elliott, © 1981. (Yes, I didn't capitalize the name for a reason, on and inside the book it is also not capitalized). This is another book written by a broadcast engineer for other broadcast engineers, and also was used in colleges as a text book for teaching electrical engineers.
Anyway, I'm going to start this with a quote that starts with the last paragraph on page 58.
Then it continues on...
Now for Figure 2.2 they referred to.
Here, in the third pane, we have an example of current magnitude, with the arcs denoting magnitude, and the arrows representing current. We have, on both sides, a current peak (and the associated voltage null, not marked, however, according to this image this change in voltage does not cause current at the point to suddenly change like you insist it does. The current remains the same though this voltage phase change.
This isn't the only source I have that demonstrates this, I have a third for you that clearly shows, with a longer antenna than this, where the current's phase actually changes.
And the third source for today, from "Radio Antenna Engineering" by Edmond A. Laport, © 1952. This is another book written by a broadcast engineer for other broadcast engineers, and was (if not still is) the most quoted book on the subject of antennas. This book is available for free if you search for it online. We are going to start with text on page 256.
Figure 3.31...
Here, the middle image, or B, is the one that is relevant to our discussion, again we have a full wavelength center fed dipole, and as we can see from the arrows present, all of the current is traveling in the same direction, or is in phase. What does it take to get out of phase currents? An example is conveniently presented here for us with the right most image, or C. On C we have a center fed dipole with two 5/8 wavelength sides, giving us a full 1½ wavelength of antenna length. This clearly shows that the current phase does not change until the current null, it isn't the voltage null that changes the current's phase, it is the current null.
There is something else Fig. 3.31 clearly demonstrates, on all of these antennas there is radiation...
I can continue, but I think this is enough for now.
The DB
NB you ssid
"Bob, you're imagining that a full wave acts the same as a 1/2 wave dipole.
Walk one leg of a 1/2 wave dipole around?
Yes, from cancellation to radiation, however the same is not true for a full wave.
Bad logic, one is right, one is wrong"
Its not like that NB, it is you that is wrong.
It makes no difference how long the wires are.
If they are parallel and closely spaced symetrically fed and the load is balanced & no conductors are near them upsetting balance,
currents on the wires will have equal magnitude & opposite phase cancelling radiation.
As soon as you start walking one leg around you get radiation increasing as the angle of the wires increases,
All lenghs of wire will radiate,
There are NO wavelengths or fractions of wavelengths of wire that won't radiate like any dipole.
I have no idea how you could possibly believe what you claim.
"Bob, you're imagining that a full wave acts the same as a 1/2 wave dipole.
Walk one leg of a 1/2 wave dipole around?
Yes, from cancellation to radiation, however the same is not true for a full wave.
Bad logic, one is right, one is wrong"
Its not like that NB, it is you that is wrong.
It makes no difference how long the wires are.
If they are parallel and closely spaced symetrically fed and the load is balanced & no conductors are near them upsetting balance,
currents on the wires will have equal magnitude & opposite phase cancelling radiation.
As soon as you start walking one leg around you get radiation increasing as the angle of the wires increases,
All lenghs of wire will radiate,
There are NO wavelengths or fractions of wavelengths of wire that won't radiate like any dipole.
I have no idea how you could possibly believe what you claim.
Bob you've presented a very convincing argument here.
I've decided that if it's actual then I need to see it thus, like viewing a cube drawing of only the cube edges from an obtuse angle, it's either facing upward toward the right or downward toward the left, depending upon the mind's eye's chosen perspective
.
...So I put on my imaginary RF visualizing glasses and dialed "voltage" so I'll be able see the voltage:
Red for positive
and
Green for negative.
I decided to start off with the collapsed antenna where both 1/2 wave sides are folded side by side as in your first 2.2 example, similar to balanced line.
I see a shape which appears similar to an hourglass on it's side, the high points and low points at the ends, red above the line of the wire and the same mirrored image in green below the line of the wire.
Now, I walked one end of the wire around so it is outstretched it into a dipole and stood back to see what appeared to resemble a full pep sine wave, a full circle of red & green voltage at the center of the now fully outstretched dipole wire, and two half-circles - cut in half vertically - on each end of the dipole.
The top half of the center full voltage circle and the two half-circles (above the dipole wires) appeared red, the bottoms below the line of the wire were green.
I now decided to view the currents but when switching my magic RF glasses to blue & yellow for current I now see only the faintest line across the middle, right where the wire is.
Ah, that's right, they are 90° out of phase!
So I folded the dipole back into a parallel balanced line to start over and got into my Heli-Drone and flew up to directly above the wire, 90° perspective from the ground view.
- Looking down on it from above I now see the currents as a complete 1/2 wave diameter circle the same size as the entire length of the folded wire, but it's a murky orange-purple... Ah yes, the two wire currents are cancelling each other, equal but opposite currents!
So I decided to return it to a dipole and radioed to my assistant on the ground to walk one of the 1/2 wave long wires around toward the North, stretching it out to the Northern-most point of this full-wave dipole.
I noticed as she walked it around, the blue on the East side of the moving wire (which was cancelling the yellow on the East side of the other, stationary, wire) began to become more blue and as she continued to walk it around it came from murky-blue pointing to the East, around toward the North then finally it was full blue on the West side of the moved wire, just like the other side of the dipole - blue toward the West.
Now, outstretched into a dipole, I see both of the full 1/2 wave long current circles, one on each side of the feed point, the entire length of each side, and still looking down from directly over the dipole, both circles are blue on the West side of the wire and yellow on the East side of the dipole, currents In-phase.
- This is the only way I can visualize in my mind's eye how they can be In-phase, by actually putting the voltage & current 90° out of phase in the physical 3D realm, as both you & The DB mentioned earlier.
So IF true, I'm left wondering what was wrong when I tried to do this on 40m using my 80m 1/2 wave 90° inverted vee.
- Must've had something to do with the way the two currents interacted in a 90° inverted vee with regard to the TOA/AOR as a full-wave inv vee on 40m.
Merry Christmas!
I've decided that if it's actual then I need to see it thus, like viewing a cube drawing of only the cube edges from an obtuse angle, it's either facing upward toward the right or downward toward the left, depending upon the mind's eye's chosen perspective
.
...So I put on my imaginary RF visualizing glasses and dialed "voltage" so I'll be able see the voltage:
Red for positive
and
Green for negative.
I decided to start off with the collapsed antenna where both 1/2 wave sides are folded side by side as in your first 2.2 example, similar to balanced line.
I see a shape which appears similar to an hourglass on it's side, the high points and low points at the ends, red above the line of the wire and the same mirrored image in green below the line of the wire.
Now, I walked one end of the wire around so it is outstretched it into a dipole and stood back to see what appeared to resemble a full pep sine wave, a full circle of red & green voltage at the center of the now fully outstretched dipole wire, and two half-circles - cut in half vertically - on each end of the dipole.
The top half of the center full voltage circle and the two half-circles (above the dipole wires) appeared red, the bottoms below the line of the wire were green.
I now decided to view the currents but when switching my magic RF glasses to blue & yellow for current I now see only the faintest line across the middle, right where the wire is.
Ah, that's right, they are 90° out of phase!
So I folded the dipole back into a parallel balanced line to start over and got into my Heli-Drone and flew up to directly above the wire, 90° perspective from the ground view.
- Looking down on it from above I now see the currents as a complete 1/2 wave diameter circle the same size as the entire length of the folded wire, but it's a murky orange-purple... Ah yes, the two wire currents are cancelling each other, equal but opposite currents!
So I decided to return it to a dipole and radioed to my assistant on the ground to walk one of the 1/2 wave long wires around toward the North, stretching it out to the Northern-most point of this full-wave dipole.
I noticed as she walked it around, the blue on the East side of the moving wire (which was cancelling the yellow on the East side of the other, stationary, wire) began to become more blue and as she continued to walk it around it came from murky-blue pointing to the East, around toward the North then finally it was full blue on the West side of the moved wire, just like the other side of the dipole - blue toward the West.
Now, outstretched into a dipole, I see both of the full 1/2 wave long current circles, one on each side of the feed point, the entire length of each side, and still looking down from directly over the dipole, both circles are blue on the West side of the wire and yellow on the East side of the dipole, currents In-phase.
- This is the only way I can visualize in my mind's eye how they can be In-phase, by actually putting the voltage & current 90° out of phase in the physical 3D realm, as both you & The DB mentioned earlier.
So IF true, I'm left wondering what was wrong when I tried to do this on 40m using my 80m 1/2 wave 90° inverted vee.
- Must've had something to do with the way the two currents interacted in a 90° inverted vee with regard to the TOA/AOR as a full-wave inv vee on 40m.
Merry Christmas!
- No one is chatting at the moment.
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