Total posts : 45366
[quote:c05f5f4791=”12vman”]Would the FCC see the center load as part of the radiator and add the coil wire length to the antenna? I have read in other references that a center load would give the best efficiency but not too many folks apply this to a legal Part-15 antenna. I guess the quesion is, Does the loading coil “Radiate” being that it’s at the center of the radiator or would it just be considered a “Load”?[/quote:c05f5f4791]
Predicting what the FCC might think of this situation is risky. But as shown in my last post, a loading coil adds so much resistance in series with the antenna current that the coil will absorb much of the available power, no matter where it is placed. On the other hand, if a loading coil is [i:c05f5f4791]not[/i:c05f5f4791] used, the SWR of a 3-meter Part 15 AM antenna is very high to a transmitter expecting a 50 ohm non-reactive load, and it can’t deliver much power into it. That is the dilemma.
[quote:c05f5f4791]For what I understand, the Rangemaster is an awsome unit and is very efficient. If there was a design that could be applied to other units using the 102″ whip theory that would just come close to the same efficiency, would be great! Rangemaster uses a torrid(sp) core multi tap ring to match the output for what I see.[/quote:c05f5f4791]
Any inductor that can produce the reactance needed for this short antenna and at the same time GREATLY reduce the DC resistance in the coil (with a good Q) will be an advantage. I don’t know the characteristics of the Rangemaster coil, but even if its DC resistance was only one ohm, that is still 20 times higher than the radiation resistance of the antenna, and the coil would absorb >99% of the transmitter power even if ground system losses were zero.
[quote:c05f5f4791]I believe the “Line of Sight” issue helps on range also.[/quote:c05f5f4791]
This is a characteristic of antenna designs like a 1/2-wave dipole used at VHF and above, where a surface wave along the Earth does not provide the signal to the receiving antenna. The useful path is by line of sight, only, and the higher the antennas, the better. But this isn’t true for MW verticals, whose radiation pattern and gain can only be developed in reference to Earth, and where the usable signal propagates by the surface wave.