What happens to the resonant frequency when inductance is increased in an antenna circuit?

• A. The resonant frequency decreases
• B. The resonant frequency increases
• C. The resonant frequency remains unaffected
• D. The resonant frequency oscillates

Answer: (A)

When the inductance in an antenna circuit is increased, the resonant frequency decreases. This relationship is rooted in the fundamental principles of resonance in RLC (Resistor-Inductor-Capacitor) circuits, where the resonant frequency is given by the formula:

[ f_0 = \frac{1}{2\pi\sqrt{LC}} ]

In this formula, ( f_0 ) represents the resonant frequency, ( L ) denotes inductance, and ( C ) signifies capacitance. As can be observed, the resonant frequency is inversely proportional to the square root of inductance. Therefore, when inductance ( L ) increases while capacitance ( C ) remains constant, the value of ( \sqrt{L} ) increases, leading to a decrease in the resonant frequency ( f_0 ).

This principle is essential in antenna design, as adjustments to inductance can directly influence the operating frequency of the antenna. Consequently, understanding this relationship is crucial for tuning antennas for optimal performance in radiotelegraphy and other forms of communication.