FCC Exam Question: 3-46F6

When would it be more desirable to use an m-derived filter over a constant-k filter?

A. When the response must be maximally flat at one frequency.
B. When the number of components must be minimized.
C. When high power levels must be filtered.
D. When you need more attenuation at a certain frequency that is too close to the cut-off frequency for a
Correct Answer: D

Explanation: M-derived filters are a specialized type of filter designed to provide a very sharp attenuation characteristic and a "pole of attenuation" (a frequency where attenuation is theoretically infinite) at a specific frequency relatively close to the filter's cutoff frequency. This means they offer a much steeper roll-off and significantly greater attenuation just outside the passband compared to a constant-k filter, which has a more gradual attenuation slope. Therefore, if you need to precisely reject an unwanted signal that is spectrally very close to your desired passband, an m-derived filter is highly desirable to achieve the necessary isolation. A) is incorrect because "maximally flat" usually refers to Butterworth filters, which prioritize a flat passband response over sharp cutoff. B) is incorrect because m-derived filters generally require more precise components or more complex designs than basic constant-k sections to achieve their sharp characteristics. C) is incorrect because filter type (m-derived vs. constant-k) relates to frequency response, not power handling. Power handling depends on component ratings and physical construction.

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Includes Elements 1, 3, 6, 7R, 8, and 9.