N121-044 TITLE: Making airborne radome structural members

TECHNOLOGY AREAS: Air Platform, Materials/Processes, Electronics

ACQUISITION PROGRAM: PMA 231

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OBJECTIVE: Develop and fabricate one or more prototype structural members, for the Hawkeye Rotodome, which will minimize structural members� effect on Radio Frequency (RF) propagation.

DESCRIPTION: Radio signals are propagated as planar waves. Different media have different propagation speeds; when optical and radio waves cross from one media to another, such as air to fiberglass, the electromagnetic waves will refract. In 1967 Victor Veselago theorized development of substances which exhibit unusual or unnatural properties at a given wavelength of interest. Hawkeye radar works in the UHF Band and the IFF works in the IEEE L Band. The Hawkeye rotodome is fabricated with fiberglass structural reinforcements that refract the RF energy increasing sidelobes and distorting their antenna patterns. Using substances which have negative refractive indices in the B Band and L Band, as part of the of the rotodome structural reinforcements, has the potential of reducing the sidelobes and antenna pattern distortion.

Structural members with a negative refractive index that can allow antenna to perform as in "free-space" for use in Hawkeye Rotodome should be developed. Materials that have low absorption will be needed to "steer" the beam around the structure with a combination of natural and negative refractive index materials. Materials with high absorption could be utilized to minimize the impacts of Sidelobe interference. The first phase should include a design for a structural member made with negative refractive index material for use in the Rotodome which will allow B and L band radio waves to propagate through them as if they were in free-space. Isolate a structural member in the Rotodome to redesign, and obtain it�s structural requirements,

PHASE I: Design and determine the feasibility of fabricating prototype structural members, for the Hawkeye Rotodome, which will minimize structural members� effect on Radio Frequency (RF) propagation.

PHASE II: Develop a prototype(s) for ground electrical and structural testing. Demonstrate the prototype representative Hawkeye rotodome at an approved test facility. Construct a revised prototype and retest. Document test plans, instructions for use, and development artifacts. Fabricate, design and electrically test additional prototype structural members to be tested in a representative rotodome. Phase II completion goal is TRL-06.

PHASE III: Finalize and transition the structural members to appropriate platforms and/or backfit to fleet aircraft.

PRIVATE SECTOR COMMERCIAL POTENTIAL/DUAL-USE APPLICATIONS: The technology could be applied to nearly any commercial-sector B or L-band Radar system that has similar power transmission/antenna/Rotodome constraints. Broadcast television equipment also shares many requirements with the E-2 Radar and could benefit from improved transmission efficiency.

REFERENCES:
1. Veselago, V. G. (1968). The Electrodynamics Of Substances With Simultaneously Negative Values of e (small epsilon) and � (smal mu). SOV PHYS USPEKHI. 10 (4), 509�514. Retrieved from http://www.turpion.org/php/paper.phtml?journal_id=pu&paper_id=3699

2. The Law of Refraction. The University of British Columbia. Retrieved from http://www.math.ubc.ca/~cass/courses/m309-01a/chu/Fundamentals/snell.htm

3. Young, A.T. (2001). An Introduction to Mirages. Retrieved from http://mintaka.sdsu.edu/GF/mirages/mirintro.html

KEYWORDS: E-2; Radar; meta-materials; negative refractive index; wave propagation; Veselago

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