simliar as in both been hat loaded 1/2waves with similar performance yes, but don't see them as the same type of antenna,
the only transmission-line mode currents i see in my minds eye with the top-one are circulating within the gamma section opposite in direction to antenna mode currents,
with the astroplane the feedpont impedance is set by the spacing of the legs to the mast forming the transmission-line,
i could be wrong but that sounds to me like a 1/2wave monopole with a 1/4wave sleeve mounted on a 1/4wave mast turned upside down,
a cst plot would show us what we need to see,
it either has radiation on the outside of the legs flowing the opposite direction to transmission-line mode currents inside the legs or it does not and i need a rethink on how it may operate.
Bob, in order to try and clear up the issue for me, where you reference the term transmission line (TML) currents often in your posts. Do you see these type currents flowing in a typical top hat, setup in the crossed (
+) configuration that are horizontal to the radiator or does you mind's eye tell you the currents in a top hat are always antenna mode currents?
Also, is what you see happen with horizontal radials attached to a vertical radiator...also producing transmission line currents, or again do you typically see antenna mode currents in radials that radiate well into the far field?
Do these two terms TML/AMC have anything at all to do with cancellation or the results of cancellation?
Are antenna mode currents (AMC) the opposite of TML currents...in that they do radiate into the far field while the TML currents do not for the most part?
I've always heard and understood that radials and top hats can effectively provide a path for return currents that allows for improved symmetry and decoupling of the coax at the feed point of a resonant radiator.
It is also my thinking...that these same currents do not radiate effectively into the far field as a result of the feed point being well balanced, and this is due to cancellation of parallel currents that are out of phase in such case, where we have currents flowing in the opposite direction...even if the magnitudes are the equal or not.
Does the instance of cancellation have any at all to do with transmission line currents and theory?
I've also heard that the currents that flow in the loop created by a typical gamma install works without effective radiation into the far fiedl due to cancellation, and I see these circular loops we find on the S4/Vector and the Astroplane also
do the same, where I see 1/2 the loop being out of phase with the other 1/2.
I hope this make sense?
