Electromagnetic penetration of slot apertures with depth and losses
Typical aerospace joints lead to apertures which are very narrow and thick. We develop a systematic analytical treatment of this type of aperture (precise conditions of validity given in the text), although the results are also applicable to apertures on a thin conducting body. An antenna integral equation with an equivalent antenna radius is used to describe the voltage across a narrow and thick aperture in a perfectly conducting plane. The result shows the voltage across the aperture has very high Q (quality-factor) resonances, because the equivalent radius is exponentially small. Transmitted power also exhibits similar behavior. When metallic and gasket losses are included, a nonlocal antenna model together with a local transmission line model is used to describe the voltage across the aperture. Good metallic walls, such as aluminum, are found to significantly reduce the penetration of an aperture of typical dimensions. Gaskets with relatively small loss tangents also result in significant penetration reductions. A simple transmission line with uniform loading is used to approximate the governing equation described in. In the lossless limit and for moderate fatness parameter this simple transmission line model is comparable in accuracy to King's three-term theory. The loading of the bolts or hinges is demonstrated to act in many cases as a short. Finally, the low frequency penetration for a narrow slot aperture of arbitrary depth is characterized by the equivalent polarizabilities (dominating longitudinal component) as a function of the ratio of the depth to the width and ratio of the length to the width. A general relationship is shown to exist between the equivalent radius and the transverse line dipole moments of a slot aperture with depth. The longitudinal equivalent polarizabilities of antennas and slot apertures are used to derive a coupling energy bound for a step function EMP. 9 refs., 8 figs.
- Research Organization:
- Sandia National Labs., Albuquerque, NM (United States)
- Sponsoring Organization:
- USDOE; USDOE, Washington, DC (United States)
- DOE Contract Number:
- AC04-76DP00789
- OSTI ID:
- 5511570
- Report Number(s):
- SAND-91-1737C; CONF-9109228-1; ON: DE91016401
- Resource Relation:
- Conference: 1991 international conference on electromagnetics in aerospace applications (ICEAA), Torino (Italy), 17-20 Sep 1991
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
GENERAL PHYSICS
ELECTROMAGNETIC FIELDS
MATHEMATICAL MODELS
AIR
ANTENNAS
APERTURES
DEPTH
ELECTRIC POTENTIAL
ENERGY LOSSES
GASKETS
INTEGRAL EQUATIONS
JOINTS
RECTANGULAR CONFIGURATION
WALL EFFECTS
CONFIGURATION
DIMENSIONS
ELECTRICAL EQUIPMENT
EQUATIONS
EQUIPMENT
FLUIDS
GASES
LOSSES
OPENINGS
SEALS
657002* - Theoretical & Mathematical Physics- Classical & Quantum Mechanics