Communications: radio wave antennas – Antennas – Balanced doublet - centerfed
Patent
1967-04-03
1979-07-24
Wilbur, Maynard R.
Communications: radio wave antennas
Antennas
Balanced doublet - centerfed
H01Q 1700
Patent
active
041624963
ABSTRACT:
A radar attenuator panel incorporating reactive elements is provided comprising a composite of electrically semiconductive or reactive layers separated by relatively non-conductive layers with the entire structure bonded together with compatible thremosetting resins. The electrically reactive attenuator layers have a complex admittance wherein the imaginary portion is substantial compared with the real portion. A sheet having a ratio of the imaginary portion to the real portion of complex admittance in the range of 0.7 to 2.0 throughout the frequency range from S-Band through X-Band is provided by impregnating a glass fabric with a phenolic resin having amorphous carbon and aluminum particles dispersed therein. The carbon is preferably present in the range of 9 to 18 parts by weight and the aluminum is preferably present in the range of 5 to 42 parts by weight per 60 parts by weight of resin.
The reactive layers are separated by a cellular honeycomb relatively low dielectric material that may be free of semi-conductive particles to obtain a controlled space between the reactive sheets. The honeycomb comprises a phenolic resin glass fabric honeycomb core. Phenolic resin impregnated glass faric sheets are employed in the sandwich for high core shear strength and to fix the location of the particles in the attenuator sheets. A phenolic-epoxy resin adhesive is employed adjacent the honeycomb core to assure good bonding thereto.
A carefully controlled gradient of electrical properties in the reactive sheets is provided between the outer surface of the radar attenuator panel and the inner surface thereof. A conductive metal layer is provided on the inner surface of the panel to provide a controlled radar reflectance into the reactive layers. By incorporating at least some reactive sheets in the radar attenuating structure, the criticality of the dielectric constant and thickness of the spacing between the reactive layers is alleviated. Thus changes in thickness of the attenuator and changes in angle of incidence of radar on the structure may be accomodated without requiring large design changes.
REFERENCES:
patent: 2877286 (1959-03-01), Vance et al.
patent: 3568195 (1971-03-01), Wesch
Downen David N.
Eichenberger Bert A.
Goodwin Lawrence
Rockwell International Corporation
Silberberg Charles T.
Wilbur Maynard R.
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