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I'm not saying the crossover point has moved from half wave downward from the tip. On a 3/4 wave antenna it will always have the crossover point at half wave. If you have a half wave monopole above the basket and a quarter wave basket then the crossover point is level with the basket. What I'm saying is - if you extend the basket upward another 1/8th wave by definition you have reduced the monopole exposed upper element length to 3/8ths wave. The question then arises where is the half wave phase cross over? Is it still on the monopole below the extended basket hoop or does the half wave use 3/8ths of the monopole in phase with an 1/8th wave from the top of the basket?
To answer this you have to imagine the modified vector as a closed sleeve antenna rather than on open sleeve. So imagine the whole of the basket is a sheet of aluminum shaped like an icecream cone with a thickness of 2mm just like a Sirio CX J-pole but instead of a cylinder surrounding the monopole, you have a cone.
During TX of said modified vector with a 3/8ths cone and a 3/8ths exposed monopole the current and voltage distribution is a vector sum of both 3/8th lengths and because there is a dead short between the two 3/8ths radiators at the feed point then the vector sum is 3/8ths of the upper exposed element in phase with an 1/8th wave of the top of the basket. The half wave crossover point is a vector sum of both 3/8th radiators which is 1/8 the way down the top of the cone.
If the cone was insulated from the monopole this would not take place. Instead, the monopole would form an half wave which would be partly obscured by the cone - in other words you'd have a folded dipole where one element is blocking the other. Because it's not insulated and it's a dead short and always 3/4 wavelengths long then both elements form a vector sum of an half wave over a quarter wave no matter where the monopole and basket are in relationship to one another.

<blockquote data-quote="nav2010" data-source="post: 752765" data-attributes="member: 14757">I&#039;m not saying the crossover point has moved from half wave downward from the tip. On a 3/4 wave antenna it will always have the crossover point at half wave. If you have a half wave monopole above the basket and a quarter wave basket then the crossover point is level with the basket. What I&#039;m saying is - if you extend the basket upward another 1/8th wave by definition you have reduced the monopole exposed upper element length to 3/8ths wave. The question then arises where is the half wave phase cross over? Is it still on the monopole below the extended basket hoop or does the half wave use 3/8ths of the monopole in phase with an 1/8th wave from the top of the basket?To answer this you have to imagine the modified vector as a closed sleeve antenna rather than on open sleeve. So imagine the whole of the basket is a sheet of aluminum shaped like an icecream cone with a thickness of 2mm just like a Sirio CX J-pole but instead of a cylinder surrounding the monopole, you have a cone.During TX of said modified vector with a 3/8ths cone and a 3/8ths exposed monopole the current and voltage distribution is a vector sum of both 3/8th lengths and because there is a dead short between the two 3/8ths radiators at the feed point then the vector sum is 3/8ths of the upper exposed element in phase with an 1/8th wave of the top of the basket. The half wave crossover point is a vector sum of both 3/8th radiators which is 1/8 the way down the top of the cone.If the cone was insulated from the monopole this would not take place. Instead, the monopole would form an half wave which would be partly obscured by the cone - in other words you&#039;d have a folded dipole where one element is blocking the other. Because it&#039;s not insulated and it&#039;s a dead short and always 3/4 wavelengths long then both elements form a vector sum of an half wave over a quarter wave no matter where the monopole and basket are in relationship to one another.</blockquote>

[QUOTE="nav2010, post: 752765, member: 14757"] I'm not saying the crossover point has moved from half wave downward from the tip. On a 3/4 wave antenna it will always have the crossover point at half wave. If you have a half wave monopole above the basket and a quarter wave basket then the crossover point is level with the basket. What I'm saying is - if you extend the basket upward another 1/8th wave by definition you have reduced the monopole exposed upper element length to 3/8ths wave. The question then arises where is the half wave phase cross over? Is it still on the monopole below the extended basket hoop or does the half wave use 3/8ths of the monopole in phase with an 1/8th wave from the top of the basket? To answer this you have to imagine the modified vector as a closed sleeve antenna rather than on open sleeve. So imagine the whole of the basket is a sheet of aluminum shaped like an icecream cone with a thickness of 2mm just like a Sirio CX J-pole but instead of a cylinder surrounding the monopole, you have a cone. During TX of said modified vector with a 3/8ths cone and a 3/8ths exposed monopole the current and voltage distribution is a vector sum of both 3/8th lengths and because there is a dead short between the two 3/8ths radiators at the feed point then the vector sum is 3/8ths of the upper exposed element in phase with an 1/8th wave of the top of the basket. The half wave crossover point is a vector sum of both 3/8th radiators which is 1/8 the way down the top of the cone. If the cone was insulated from the monopole this would not take place. Instead, the monopole would form an half wave which would be partly obscured by the cone - in other words you'd have a folded dipole where one element is blocking the other. Because it's not insulated and it's a dead short and always 3/4 wavelengths long then both elements form a vector sum of an half wave over a quarter wave no matter where the monopole and basket are in relationship to one another. [/QUOTE]

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