Question
What is receiving directivity factor (RDF)?
Answer Options
- A) Forward gain compared to the gain in the reverse direction
- B) Relative directivity compared to isotropic
- C) Relative directivity compared to a dipole
- D) Peak antenna gain compared to average gain over the hemisphere around and above the antenna
Correct Answer: D
Explanation
The Receiving Directivity Factor (RDF) is a figure of merit specifically used for comparing receiving antennas, especially those designed to maximize the rejection of noise from the horizon and the atmosphere (such as LF or MF receiving antennas). It quantifies the antenna’s ability to focus on the desired signal while rejecting unwanted noise.
RDF is defined as the ratio of the peak antenna gain compared to the average gain over the hemisphere around and above the antenna. A higher RDF indicates that the antenna is better at suppressing noise and interference arriving from directions other than the desired signal’s direction (often low-angle, long-distance skywave signals).
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