To lower the resonant frequency of a Hertz antenna, you would place an inductance in series with the antenna.

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Multiple Choice

To lower the resonant frequency of a Hertz antenna, you would place an inductance in series with the antenna.

Resonant frequency is set by the balance of inductive and capacitive reactance in the antenna circuit. For a Hertz antenna, you can think of it like an LC resonator where the resonance occurs when the inductive and capacitive effects cancel each other. The condition roughly follows f0 ≈ 1/(2π√(LC)); as the inductance L increases, the resonant frequency falls. Adding an inductor in series with the antenna increases the total inductance the signal sees, so the frequency at which X_L and X_C cancel moves to a lower value. That’s why this method lowers the resonant frequency. Placing inductance in parallel with the antenna changes the impedance in a different way and doesn’t directly push the resonance to a lower frequency. Putting a component across the transmitter or in the receiver doesn’t tune the antenna itself; it affects either the source/load or other parts of the circuit, not the antenna’s own resonance.

Resonant frequency is set by the balance of inductive and capacitive reactance in the antenna circuit. For a Hertz antenna, you can think of it like an LC resonator where the resonance occurs when the inductive and capacitive effects cancel each other. The condition roughly follows f0 ≈ 1/(2π√(LC)); as the inductance L increases, the resonant frequency falls.

Adding an inductor in series with the antenna increases the total inductance the signal sees, so the frequency at which X_L and X_C cancel moves to a lower value. That’s why this method lowers the resonant frequency.

Placing inductance in parallel with the antenna changes the impedance in a different way and doesn’t directly push the resonance to a lower frequency. Putting a component across the transmitter or in the receiver doesn’t tune the antenna itself; it affects either the source/load or other parts of the circuit, not the antenna’s own resonance.

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