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Capacitance hats on antenna systems are not magical. A radio antenna is a radio frequency energy load that possesses the properties of a radiator. In doing so, the antenna performance is, to some degree, governed by ohms law. Therefore, we can draw a schematic of the antenna as individual electronic components; resistor, capacitor and inductor. The inductor and capacitor produce REACTANCE (Xl/Xc), either inductive or capacitive. The resistor produces a pure RESISTANCE (R). The combination of net reactance and resistance equals the IMPEDANCE of the antenna. Each antenna has a specific impedance at a specific frequency. That means as the frequency changes something in the formula changes the impedance. That something is the reactance.
We can then draw the conclusion that a “capacitance hat” on an antenna adds capacitance to the antenna. This is done primarily to raise the impedance of the antenna load. The antenna need not be resonant to radiate. In fact, resonance only actually occurs in the antenna system at a single frequency when both flavors of reactance cancel out leaving the antenna nearly resistive only. You will notice most antennas are listed as having a specific working impedance, 50 Ohms and such. The working impedance changes as the frequency of the radio energy fed into the antenna changes. This helps determine the bandwidth of the antenna.
So, all that the capacitance hat would accomplish for the 102 inch whip on the Rangemaster is raise the impedance of the antenna. By doing so, the final tuning /tank circuit of the transmitter (which is designed for very low impedance, 2-3 Ohms) would very likely not tune the transmitter to the “cap-hat” antenna. In short, the transfer of energy from the transmitter to the antenna would be much less; certainly not enough to be overcome the small improvement in efficiency of the
cap-hat” antenna system.
This might be as clear as mud, but leave it said, others have expressed their skepticism here. I echo their thoughts.