eddie, the currents are in phase as you note, its the physical layout of symmetrical radials/hats that causes the cancellation of radiation.
nospec, I probably would have thought it doesn't make sense either until I learned to understand the idea, and why the "Split feed point" feature is provided.
When using the split feed point we are not using two feed lines nor do we have two feed points. The feature is just like it says, "Split." The feature is a virtual consideration and is not a physical reality. Check your manual for virtual features and/or split feed points.
Eznec will not allow us to place a feed point at the junction of two wires and I believe 4nec2 does the same.
So, in the case with a two wire dipole we can either locate the feed point on either wire at the end that is close to the connection, near the center of the dipole, or we can use a Split feature that allows us to split the feed point between the two wires at the virtual center of the connection of the two wires. This then places the feed point closer to the wire ends, splitting between the two wires at the connection and gets the feed point closer to the center of the dipole.
This is a virtual type feature that allows one to produce a dipole model that duplicates theory correctly and it minimizes the current differences in the two wires of the dipole and that provides for better symmetry and balance at the feed point. Only the Antenna View physically shows the split, all calculations include only one feed point, so I guess we should consider this a math function only.
You are using 4nec2, right?
If you look back at GHZ24's model of the L shaped dipole he posted earlier in this thread on the AstroPlane you will see the same two "0" "0" at the feed point he uses in his 4nec2 program, so you too can use the feature.
Note: this Split feature can only be used with two wire connections. So a two wire dipole with a mast attached in the center will have to use the standard feed point assignment feature (non-split), and that will place the feed point, at a minimum, several degrees away from the physical center of the model. Therefore there will remain a small amount of asymmetrical imbalance due to reactance in the model.
lets make up our own laws of physics about hat loading, radiation resistance etc , misuse software to make an astroplane look way better than it is and post that crap all over a forum,
ampower has competition no doubt.
Sory, i'm no speak english.
Well, if it comes to feeding a dipole at the center, just have to do it with a odd number of segments, we choose the center segment and problem solved.
If it is an inverted v antenna, only the middle segment bends 45 degrees and problem solved.
i should have quoted you eddie:blushing:
"As a result the models with even number of radials always shows all radials are in phase including opposing radials, and as I understand this aspect of antenna theory, the two opposing radials with currents flowing out toward the open tips should be out of phase with each other...and thus cancel each other out into the far field"
Astroplane is a decent antenna; but I certainly would call it the best vertical ever.
Now, a Vector 4000 or a GainMaster are still top of the list IMO.
Bob Nospec is new to the forum, and he just opened a thread to talk about his opinions for the best antenna he had the AstroPlane. We're not into the Advanced Study of Antenna Theory 502 yet, we're still talking mostly about our opinions.
Some of these guys don't even know about your previous life battling the almighty ampower in a world of nonsense and bitterness, where there were no winners...just losers.
I was never impressed with anything that guy said, so I would just forget about all of those old bad experiences if you can.
I understand you are using an interpreter Nospec, but I think I understand you here.
Can you make a wire bend in the middle of a wire when making a one wire inverted V while using 4nec2?
Can you make an L shaped dipole using a single wire and bend it at the apex where the two legs of the L shape connect and where the feed point should go?
CE
GW 1 3 0 0 7.25 -0.0707107 0 7.25 1.e-3
GW 2 150 -0.0707107 0 7.25 -1.979899 0 5.34081171 1.e-3
GW 3 150 0 0 7.25 1.90918831 0 5.3408117 1.e-3
GE 0
EK
EX 6 1 2 0 1 0
GN 0 0 0 0 13 0.005
FR 0 1 0 0 27.2 0
Beginners in modeling should never assume their models are more accurate than real world results. Especially when the results do not agree. The Astroplane is ONLY the best vertical when you are in a position where you can't install a longer antenna. It may be the best SHORT vertical antenna but it is definitely not the best vertical ever.
This is not to say that "longer" automatically means a stronger signal. That will be dependant on if the longer antennas radiation currents are in a constructive phase along the entire length of the antenna. Something both the Gain-Master and Vector have accomplished 100%.
OK I have to retract my previous statement I reversed wires on nospec's Inverted Vee model and found no effect at all.
I know I've seen it matter before I just can't remember where.
Must be something else at work. Wish I could remember what model it was so I could pin-point the circumstances. I do know it did not have a split feed
On marconi's sigma 4 the split feed didn't make a lot of difference but on that L I posted it makes a large difference (to remove one or the other).
Especially in the relative vertical vs horizontal polarization.
24, I asked nospec if his Inverted V was 1 wire and if he could bend it in the middle like I think he is suggesting. After opening his model up I see it is made up of three wires, with one really short wire in the middle where the feed point is inserted. I think I understand that 4nec2 will do the split source as a default under certain conditions where two wires are attached. Using Eznec the feature is an option with the standard application of the source as the default setting.
I wish I was as familiar with 4nec2 as you are. I have to trial and error my way thru the procedures and I get plenty of errors that closes the program.
One issue I have is the program does not see my printer and the print function allows me to find a printer, but when I select my printer, nothing happens. When I click on print the program closes. Is there a setup outside of the program that needs to be setup so 4nec2 is fully implemented?
I don't know either...why you saw change in performance results before, and now you don't.
I posted a response to you earlier that the only difference I see is with the currents and phase. I think I posted all of my output so maybe you could see what I was seeing. If you don't see the same or similar...then I don't have any more ideas why switching matters.
Did you check the currents and phase out on either your's or nospec's model?