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Current across the antenna loading coil - from scratch
"Richard Clark" wrote Hi Yuri, This must be a convention that is particular to only a very few Hams. The FCC database describes AM antennas in both electrical and physical height as follows. WGOP 80.00° tall 125.2 meters tall 540 kHz WWCS 63.50° tall 98.8 meters tall 540 kHz WFTD 79.00° tall 64.0 meters tall 1080 kHz KYMN 118.60° tall 92.3 meters tall 1080 kHz WWLV 90.00° tall 47.2 meters tall 1620 kHz WTAW 204.00° tall 106.7 meters tall 1620 kHz There may be some discrepancy, but it certainly looks like antenna specification is by the electrical equivalent of the physical height (and whatever l/d fudging) and with only one happening to be 90°. Further, given most references (for professionals) is aimed at a common specification that is largely driven by this agency, it would seem odd to step out of this expectation to change to calling all antennas 90° simply because they resonate. http://www.fcc.gov/mb/audio/amq.html 73's Richard Clark, KB7QHC That's fine, no argument there. But do you agree that there are towers of X height in meters and when "naked" having Y electrical degrees, loaded with top hat of size S, not changing the physical height, but adding Z degrees. So the top hat adds some degrees to the tower. Is it such ham radio crime to say that coil can do that too, if it is inserted within the radiator? We use imaginary lumped inductor to understand coils better, but we can not use electrical degrees to 'splain the behavior of coiled antenna wire? I think we are progressing into antenna modeling and design and I see nothing wrong with using degrees to describe electrical properties (resonance) of the loaded radiator. 73 Yuri, K3BU actually WWLV 90.00° tall 47.2 meters tall 1620 kHz should show closer to 92 deg. and assuming that they use fatter tower, even more. |
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