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Short note: E-plane tee

Short answer

E-plane tee is a series tee with side arm on the broad wall. Input at side arm splits equally to collinear arms 180 degrees out of phase; equal in-phase inputs cancel at side arm. Its S-matrix has 1/2 and 1/sqrt(2) entries.

Write a short note on E-plane tee.

An E-plane tee (series tee) is a waveguide tee junction in which the side arm (port 3) is attached to the broad wall of the main guide, so the side arm axis is parallel to the E-field of the TE10 mode. Ports 1 and 2 are the collinear arms.

          port 3 (E-arm)
             | |
   ----------+ +----------
 (1)                    (2)
   -----------------------

Behaviour:

  • Input at port 3 divides equally into ports 1 and 2 180° out of phase (the E-field lines bend in opposite directions).
  • Equal in-phase inputs at 1 and 2 cancel at port 3; anti-phase inputs add at port 3.
  • It acts like a series connection of the side arm with the main line.

S-matrix (lossless, side arm matched):

       |  1/2    1/2    1/√2 |
 [S] = |  1/2    1/2   -1/√2 |
       |  1/√2  -1/√2    0   |

Uses: power division with phase reversal, balanced mixers, impedance tuners (with a sliding short in port 3) and as part of a magic tee.

✓ Answer checked by Claude Opus 5.5 (high effort)

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