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This course cover two topics of about 10 hours of lectures each plus
exercises, all concentrated in a week. The first part cover the basic
issue concerning with the fundamentals of high-frequency techniques;
the second part is concerned with travelling wave antennas and basic
leaky wave phenomena.
High-frequency techniques
- 1. Introduction on fundamentals - Equivalence principle, PO
and Kirchhoff aperture radiation - Non uniform asymptotics - Space
domain and spectral diffraction integrals- GO+diffraction, PO+fringe.
- 2. Uniform asymptotic evaluation of radiation and scattering integrals.
- 2.1 Single variable diffraction integrals- interacting
(saddle-point) - pole (wedge problem - spectral domain) - interacting
(saddle-point) - end point (wedge problem-spatial domain)- interacting
(saddle-point) - branch point (Sommerfeld problem) - three collinear
saddle points (curved face).
- 2.2 Double variable diffraction integrals- saddle point 2D/partial derivative saddle points - saddle points and poles.
- 3. Uniform theory of diffraction - Edge problem- Double edge- Corner problem - Curved surfaces.
- 4. Incremental diffraction theories- PTD and ILDC- Incremental theory of diffraction (ITD)
- impedance BC and generalized impedance BC.
- 5. Truncated Floquet Wave (FW) diffraction theory - Semi-infinite array- Corner array
- multilayer environment .
Travelling wave antennas
General features and applications. Fields of a traveling-wave source,
leaky waves in open structures. Characterization of traveling-wave
antennas: determination of the phase and attenuation constants,
relation to the radiation properties. Mechanisms employed to produce
leakage: apertures, asymmetries, use of suitable modes. Scanning
behavior, phased arrays of leaky-wave line sources, unit-cell approach.
Transverse-equivalent networks, aperture admittance,
transverse-resonance technique. Radiation-pattern shaping, aperture
distribution: tapering procedures for leaky-wave antennas. Example of
practical antennas: partially-open metallic waveguides, dielectric
structures, printed lines. Feed, losses, manufacture issues.
Measurement techniques.
Responsibles:
S. Maci - macis@ing.unisi.it
F. Frezza - fabrizio.frezza@uniroma1.it
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