Question
As a conductor’s diameter increases, what is the effect on its electrical length?
Answer Options
- A) Thickness has no effect on electrical length
- B) It varies randomly
- C) It decreases
- D) It increases
Correct Answer: D
Explanation
The electrical length of a conductor (or antenna element) is its length expressed in terms of the signal wavelength (e.g., 1/4 wavelength). The physical length required to achieve a specific electrical length is affected by factors such as velocity factor and the conductor’s geometry. In the case of a single conductor, the electrical length relates to the characteristic impedance of the wire as a transmission line.
As a conductor’s diameter increases, its effective capacitance to the surroundings increases, and its characteristic impedance decreases. This change in impedance makes the conductor behave as a slower-wave transmission line. Consequently, the effect of increasing a conductor’s diameter is that its electrical length increases relative to its physical length, meaning the element must be physically shortened to maintain the same resonant frequency.
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