lwa phase velocity
DESCRIPTION
space harmonicsTRANSCRIPT
• Space harmonics are expansion of field similar to fourier expansion but are not power orthogonal due to mutual coupling
• Spatial harmonics converge easily in evaluating field integrals and helps in accurate estimation of properties of radiation pattern and thereby designing antenna
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 field Microscopic 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 by
For 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.
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