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Old October 23rd 08, 04:09 PM posted to rec.radio.amateur.antenna
John KD5YI[_3_] John KD5YI[_3_] is offline
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Posts: 24
Default Antenna design question


"K7ITM" wrote in message
...
On Oct 22, 9:52 pm, "John KD5YI" wrote:
"Richard Harrison" wrote in message

...



Mike, N3LI wrote:
"Why would the velocity be less at increased (antenna element) width?"


Let B = the phase velocity on the antenna element, in radians per unit
length. 2pi/B = wavelength on the element.
Therefore, 2pi/B=velocity of phase propagation.
Due to the behavior of of open-circuited transmission lines and
open-circuited antennas:
B=2pif times sq.rt. of LC radians / unit length.


2 pi f / B = velocity of propagation.


It is intuitive that a fat antenna element has more L & C than a thin
element and thus a lower velocity of propagation.


Best regards, Richard Harrisob, KB5WZI


Hmmmm... my straight wire inductance equation from the ARRL handbook
indicates smaller wire diameters have larger inductance.

???

73,
John


Not surprisingly, that's what E&M texts say too--or leave as an
exercise. With a larger diameter, there's less net magnetic field for
a given current, so less energy stored, so less inductance.

Cheers,
Tom


So, then, it isn't intuitive (to me, at least) that a fat antenna has more
inductance. Intuitive to me is that the reverse may be true.

Cheers to you, too, Tom.

John