Home › Forums › temp › Loading coil chart for 10-ft broadcast AM vertical antenna › Re: Maybe i could
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[quote=YvesRoy]Can you give me the diameter of your 102 inch whip antenna? Maybe i could do a second chart for this whip antenna.[/quote]
Just to note that for a given operating frequency, reducing the average diameter of the 3-meter-long section of radiator attached to a Part 15 AM tx at its “antenna output” terminals will increase the capacitive reactance of that radiator, and at the same time reduce its SWR bandwidth (eg, it will increase the “Q” of that radiator).
This means that the X(sub L) of the loading coil needed at the feedpoint at the base of that antenna to bring it to resonance will increase. Typically that increases the r-f losses in that coil, and so lowers the radiation efficiency of that antenna configuration.
So with other things equal, the smaller the average diameter of the radiating structures (including those of the “ground lead,” “ground conductor,” and/or “ground wire,”) the less will be the overall radiation efficiency and r-f bandwidth of that radiating system.