Lwa Phase Velocity

Click here to load reader

download Lwa Phase Velocity

of 10

  • date post

    25-Dec-2015
  • Category

    Documents

  • view

    9
  • download

    2

Embed Size (px)

description

space harmonics

Transcript of Lwa Phase Velocity

Slide 1

Space harmonics are expansion of field similar to fourier expansion but are not power orthogonal due to mutual couplingSpatial harmonics converge easily in evaluating field integrals and helps in accurate estimation of properties of radiation pattern and thereby designing antenna

Spatial harmonics TE & TM modesConverges rapidly for small values of d/0 Converges rapidly for large values of d/0

Travelling with uniform amplitude in closed guide along transverse direction.(pass band)Evanescent in closed guide along transverse directionWaves transport energy in direction transverse to axial (phase shift wall wave guide) Waves transport energy in axial direction(opaque wall)Satisfies boundary conditions when addedSatisfies boundary conditions separatelyNot power orthogonal by naturepower orthogonal

Floquet theoremTranslational symmetry of axially periodic structures in which mode is guided axially.

Cross-sectional complex field distribution of a periodic structure remains unchanged under an axial translation of observational point through period d , while amplitude multiplies itself by a complex constant Macroscopic fieldMicroscopic field

Fourier expansion of a Bloch wave indicates that field of a normal mode of axially periodic structure is expressible in terms of an infinite number of travelling waves

Each spatial harmonic has a phase velocity given byFor sufficiently large values of abs(n) all harmonics are axially slow n >= 0 forward travelling wavesLarge negative values if n backward travelling waves

Orthogonal polarization end fire scanning possibleWave number key for all radiation characteristicsLeakage interruption of current flow by slots on top wall

Wide microstrip shorted by vias at edges to form SIWEasy integration with planar circuits as a promising antenna for integrated microwave and millimeter wave applications

[17] Collin, R. E., & Zucker, F. J. (1969). Antenna theory. 2 (1969). McGraw- Hill, ch. 19 and 20. REFERENCES