Frequency-response fundamentals: a Bode diagram consists of which plots for a linear system's transfer function when expressed versus frequency?

Introduction / Context:
Bode diagrams are the cornerstone of single-input single-output frequency-response analysis. They allow engineers to read gain margins, phase margins, and asymptotic behavior directly from log-scale plots, aiding robust control design and filter synthesis.

Given Data / Assumptions:

• AR denotes amplitude ratio (magnitude) of the transfer function.
• Φ denotes phase angle in degrees (or radians).
• Frequency axis is logarithmic to span decades efficiently.

Concept / Approach:
A complete Bode plot has two subplots sharing the same log-scale frequency axis: the magnitude (in decibels, 20 log10|AR|) versus log(f), and the phase Φ versus log(f). Using a logarithmic frequency axis linearizes slope interpretations and makes corner frequencies and asymptotes easy to visualize across wide ranges.

Step-by-Step Solution:

Verification / Alternative check:
Classical control texts show straight-line asymptotes for poles/zeros on the magnitude plot and characteristic phase transitions around break frequencies.

Why Other Options Are Wrong:

Common Pitfalls:
Forgetting to convert magnitude to decibels; while raw |AR| can be plotted, the “Bode magnitude” is conventionally in dB on a log frequency axis.

Final Answer:
log(AR) vs log(f) and Φ vs log(f)