Field distribution in TE10 mode — location of maximum E-field For the dominant TE10 mode in a rectangular waveguide, where does the electric field have its maximum magnitude?
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Aalong centre line of broad wall (i.e. x = a/2)
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Balong the broad wall (i.e. x = 0 and x = a)
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Ceither (a) or (b)
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Dneither (a) nor (b)
Answer
Correct Answer: along centre line of broad wall (i.e. x = a/2)
Explanation
Introduction / Context:Knowing where fields peak inside a waveguide is critical for breakdown assessment, probe placement, and coupling design. In TE10, the dominant transverse electric field varies sinusoidally across the broad wall dimension.
Given Data / Assumptions:
- Rectangular waveguide with width a (broad wall) and height b (narrow wall).
- Mode: TE10 (m = 1, n = 0).
Concept / Approach:The principal field component varies as a cosine function across the a-dimension and is uniform across b. Boundary conditions enforce zero tangential electric field at the conducting walls (x = 0 and x = a), with a maximum at the midpoint x = a/2. Thus, the electric field maximum lies along the center line of the broad wall.
Step-by-Step Solution:
Model transverse field: E(x) ∝ cos(π x / a).At x = 0 and x = a → conductor boundary condition forces field components to zero.Maximum occurs at x = a/2 → center line across the broad wall.Verification / Alternative check:Standard field plots and coupling-probe placements show strongest coupling at x = a/2 for TE10, confirming the location of the E-field maximum.
Why Other Options Are Wrong:
- B: The field is zero at the side walls, not maximum.
- C/D: Contradict the sinusoidal distribution and boundary conditions.
Common Pitfalls:Confusing TE10 with higher-order modes; misapplying boundary conditions at conductor walls.
Final Answer:along centre line of broad wall (i.e. x = a/2)