You need volts or uv to generate the current that lags 90 degree behind it. Without voltage/potential difference to kickstart the current there is no current.
Thats why i max lies 1/4 wave down the radiator from Vmax.
I mentioned to Bob above that this comment was a joke...just like Bob indicated Jazz. You must have missed it.
If you looked at coax or basket as a 3 conductor line when cmc is present instead of a 2 conductor line you would understand it better.
The shield or basket is 2 conductors at RF not 1 due to the skin effect or the going up and looping over Donald mentioned.
I don't see the cone basket as coaxial and I don't think it will produce CMC for that reason. Even if it does, the currents are very small according to my Eznec model. I've explained this idea above already.
Its exactly that misunderstanding that lead to bazookas/sleeved dipoles.
You don't need to add a 3rd conductor. Its already there. With skin Effect RF current only penetrates microns on the inner surface and outer surface of shield/basket.
The third conductor idea, that IMO is misapplied in this thread, came from an idea published in the Eznec manual that I previously posted for Bob, maybe in another thread. With Eznec we can model a feed line attached to an antenna, but we have to add an extra wire in order to see the currents flowing...
assuming there are CMC's present on the feed line. This instruction in the manual does not talk about currents flowing on the antenna elements perse, and this has been misconstrued to mean radials with added wires in this thread. DB, tells us that the model was no-way-no, but he didn't like my questions as I was trying to understand what he did. I understand better now, but he will not answer my questions. I think a lot of folks must be confused at what DB was trying to do. If you read his latter post closely you will see that he told us stuff that was somewhat lost in the words.
The current on the centre conductor/radiator is I1, the equal and opposite phase current on inside of shield/basket is I2 and cancels I1 so no radation occurs.
Jazz, I agree with your description except to exclude the cone.The structural ratios necessary for coax to work as coax does...are not present in the the S4 radial cone design. It might look like a transmission line, but it is not coaxial like you described above Jazz.
I contend, instead, that if there are small currents flowing on the radials after cancellation, like you suggest above, those currents are antenna mode currents remaining as a result of incomplete cancellation between I1 and I2.
I further contend that any such current difference that exist after cancellation...is minimal at best and this difference can be constructive or destructive depending on the antenna construction. Again, whatever the difference is...it is not much according to my Eznec model.
I do not contend that there are no currents flowing on the cone...I just say the currents are minimal at best, regardless if they add to or substract from the top 1/2 wave element.
On the outside of the shield/basket is I3. It is equal and the same phase as I1 and opposite phase but equal to I2. It has no I4 to cancel radiation so its common mode as opposed to the transmission mode of I1 and I2 so without cancellation it radiates in phase with the I max of the radiator.
I agree we can experience I3 flowing as CMC on coax, if the feed point is not symmetrical or located badly. I disagree that the S4 radial cone is coaxial, and thus the cone does not produce CMC. My description of a pigtail suggest that as soon as the coax construction is altered or disrupted...the pigtail starts to radiate like and antenna, and that current is antenna mode currents.
Its exactly how and why a T2LT and Gainmaster work so well.
Both antennas noted use coax to produce the CMC's that radiate. We can't substitute tubing or wire for the coax in these antennas...like is being suggested for this idea for the radial cone structure in this thread.
The best way of looking at the basket is a transmission line shorted at one end and being of a cone shape profile giving it 0 impedance at base and high non constant impedance to top of basket. Which is how it matches to the top end fed high impedance 1/2wave radiator.
IMO a Jpole is considered by many to produce CMC on the feed line. If the 1/4 wave base area radiates...is it considered to be CMC' or antenna model currents? Either way the currents are typically very small depending on construction and location. IMO the J-Pole produces antenna mode currents from the bottom, if any, and antenna mode currents on the radiator. If there are CMC's flowing on this antenna at all...they are flowing on the feed line down to ground.
In my opinion similar to how a 1/2 wave or 5/8 wave coil is tapped. Thats deliberately made shorter creating capacitive reactance to allow inductive feeding of inductive equal reactance.
I believe in the sigma 4 the radiator is made slightly longer to introduce inductive reactance so it can be gamma/capacitive fed with an opposite but equal capacitive reactance.
In my Eznec model of a 3/4 wave length antenna I find on raising the radials the radiator needs to be made longer in order to remain resonant...just like you describe.
Thats how I see it anyway. Which would also tally up with a non apparent colinear Cebik stated.
Jazz, I understand what Cebik told Bob, but when I asked Bob what it meant...he wasn't sure and they did talk anymore.
I've said it before, misguided as it may be, that all an antenna needs in order to be consider a collinear...is that it shows two current maximums. A 5/8 wave radiator is also referred to as a collinear antenna in the CB world. IMO, way back the idea was coined by HyGain describing their CLR2...and they described it as a collinear.
As the common mode current and varying transmission mode impedance transformation isn't staring you in the face especially if you view coax as a 2 conductor cable.
Just my take on it.
I understand the idea as it pertains to coax. I just don't see it concerning the radial cone on the S4 design. The cone is just radials, not coax. It is radiating the currents remaining after L1 and L2 do their thing and cancel to the extent possible...like you've noted above.
I accept that you have given us your opinions Jazz. I hope you accept that this is my opinion...even if we differ.