Question
Which of the following describes a log-periodic antenna?
Answer Options
- A) Element length and spacing vary logarithmically along the boom
- B) Impedance varies periodically as a function of frequency
- C) Gain varies logarithmically as a function of frequency
- D) SWR varies periodically as a function of boom length
Correct Answer: A
Explanation
The log-periodic antenna (LPA) derives its name from the relationship that defines the dimensions of its elements. To achieve its wide-bandwidth, frequency-independent characteristics, the length of each successive element and the spacing between them follow a defined mathematical progression.
The defining characteristic is that element length and spacing vary logarithmically along the boom. This logarithmic relationship ensures that for any frequency within the design range, there is always a pair of adjacent elements that act as the active radiating portion, maintaining consistent gain and impedance across the entire operational range.
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