Question
What challenge is presented by a small wire-loop antenna for direction finding?
Answer Options
- A) It has a bidirectional null pattern
- B) It does not have a clearly defined null
- C) It is practical for use only on VHF and higher bands
- D) All these choices are correct
Correct Answer: A
Explanation
A small wire-loop antenna is commonly used for direction finding (RDF) because its figure-eight pattern provides deep, easy-to-locate nulls (points of minimum reception). However, this pattern presents a specific challenge in unambiguously determining the signal’s bearing.
The challenge presented by a small wire-loop antenna for direction finding is that it has a bidirectional null pattern. This means that while it tells the operator the line on which the signal source lies (e.g., a line pointing east-west), it cannot distinguish whether the signal is coming from 90° (east) or 270° (west). To solve this ambiguity, a separate ‘sense’ antenna is often used (see E9H08).
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