Wave Propagation and Polarization
Transverse Electromagnetic Modes:
A mode is a particular field configuration.
TEM mode: E and H fields are contained in a local plane
(equiphase plane).
Plane waves: Equiphase planes are parallel.
Uniform plane wave: The field amplitudes are uniform over
the equiphase plane.
Uniform Plane Waves in an unbounded Lossless Medium:
Wave Impedance:
Ex:
Given the E field for a uniform plane wave
Find H ?
Ans:
Phase and Group Velocities, Power and Energy Densities:
Phase Velocity:
Energy Densities:
Group Velocity:
Time Average Power Density:
Standing Waves:
First traveling wave + Second traveling wave = Standing wave.
For
The instantenous field expression:
The standing Wave Ratio (SWR):
Pure standing wave (|Γ|=1):
Uniform Plane Waves – Oblique Angle:
The E field does not have a y-component: Transverse electric
to y (TEy) mode.
The phase constants,
and
or
The planes of constant phases,
Ex:
For TMy wave, write the E and H field expressions, assuming
the amplitudes are E0+ and E0-
Ans:
Wave Impedance:
Phase and Group Velocities:
(Phase and Group Velocities of a uniform plane wave)
Power and Energy Densities:
where
Ex:
For TMy wave, derive expressions fort he average power
density along β+ direction and for the directional power
densities along the +x and z directions.
Ans:
where
Transverse Electromagnetic Modes in Lossy Media: