1. “FREQUENCY SELECTIVE SURFACES (FSS): THE BIRTH OF STEALTH”
A TECHNICAL BRIEFING FOR AMATEUR RADIO OPERATORS
“FREQUENCY SELECTIVE SURFACES (FSS): THE BIRTH OF STEALTH”
PRESENTED TO:
ARASWF
NAPLES, FL 34119
February 2019
PRESENTED BY:
DR. AL TORRES
KP4AQI 1 1

2. January 2019: “RLC: La Familia (the Family)”
For Year 2019
January 2019: “RLC: La Familia (the Family)”
February 2019: “Frequency Selective Surfaces (FSS): the Birth of Stealth”
March 2019: “Dielectric Resonator (DR) Antennas: Small, and Broadband Radiators” 2

3. PRESENTATION OUTLINE Introduction
FSS Inductive and Capacitive Configurations
FSS for Stealth Aircraft
FSS Typical Elements
A Low Pass Dichroic Combiner
Picture of Dichroic Combiner
SUMMARY 3 3

4. Introduction
A frequency-selective surface (FSS) is any thin, repetitive surface (such as the screen on a microwave oven) designed to reflect, transmit or absorb electromagnetic fields based on the frequency of the field. In this sense, an FSS is a type of optical filter or metal- mesh optical filters in which the filtering is accomplished by virtue of the regular, periodic (usually metallic, but sometimes dielectric) pattern on the surface of the FSS. Though not explicitly mentioned in the name, FSS's also have properties which vary with incidence angle and polarization as well - these are unavoidable consequences of the way in which FSS's are constructed. Frequency-selective surfaces have been most commonly used in the radio frequency region of the electromagnetic spectrum and find use in applications as diverse as the aforementioned microwave oven, antenna radomes and modern metamaterials.

5. Introduction (Cont.)
FSS are the basic foundation for the generation of stealthy platforms. They allow the transmission and reflection of electromagnetic waves, at certain frequencies, while maintaining the physical and structural integrity of the platform or object.
FSS in essence are periodic surfaces which can be configured as high pass, band pass, or low pass of electromagnetic waves or signals (radar, communications, microwave sources, etc.) .

6. FSS Inductive and Capacitive Configurations

7. The Frequency Selective Surface

8. FSS Typical Elements

9. A Low Pass Dichroic Combiner
Allows the transmission of RF below 100 GHz
Excellent dichroic combiner for RF and Electro Optical sources
Great for Space Blanket application…..keeps solar radiation from Space antennas
Made from Classical FSS elements

10. Low Pass Dichroic Combiner

11. Equivalent Circuit Model

12. FSS Theory and Design

13. SUMMARY WE HAVE DEFINED WHAT IS A FREQUENCY SELECTIVE SURFACE (FSS)
THEY ARE NORMALLY “EMBEDDED” IN RADOMES AND METAL SURFACES FOR STEALTHY AIRCRAFT
THE SURFACES HAVE COMPLIMENTARY EQUIVALENTS TO MOST CIRCUITS AND CIRCUIT DESIGN (INDUCTORS AND CAPACITORS)
MANY APPLICATIONS FOR SPACE PROTECTION OF ANTENNAS, AIRCRAFT AND STEALTH IMPLEMENTATIONS, DICHROIC REFLECTORS FOR RF AND ELECTRO-OPTICAL COMBINERS
USED BY ELECTROMAGNETIC DESIGNERS FOR MULTIPLE APPLICATIONS 13 13

14. MORE INFORMATION or COPY OF PRESENTATION
SEND AN TO THE FOLLOWING URL:
CONTACT ME AT:
AL TORRES
KP4AQI
P. O. BOX 24283
DAYTON, OH 14 14