Electromagnetic materials and structures for SWaP-C optimization of broadband permeable antennas
Abstract
ABSTRACT # Approved for Public ReleaseThis proposal addresses ONR#s Communications and Networking Program interest in antennas withhigh spectrum/energy efficiency to support high throughput communication networks under challenging battlefield conditions. Specifically, we address the need for electrically small, low-profile, multi-function antennas, operating over wide (2:1) to broad (10:1) frequency bandwidths. The technology of choice to meet these needs is the conformal permeable antenna: Intrinsically designed to be broadband and multi-function, these antennas offer novel solutions for C2, sensor, and weapon systems that mitigate conventional communications system impairments and help improve performance and reliability.These antennas surmount the greatest impairment experienced by conventional antennas in the battlefield environment. Whereas all linear, passive, electrically small antennas are constrainedby the laws of Physics to the same maximum Gain-Bandwidth Product (GBWP) infree space, this is not so in the realistic battlefield environment. DoD communication platforms, supporting multiple functions, across multiple frequency bands, are driven by the RCS survivability requirements to crowd multiple antennas into an ever-shrinking real-estate. But when conventional metal-and-dielectric antennas are forced into an electrically small form factor, in intimate proximity to the communication platform, their GBWP degrades rapidly. This is because radiating electric currents induce image currents on the platform that always oppose the source currents. As a result, the antenna#s operational GBWP becomes 10 to 1000 times smaller than the theoretical free space maximum. The only kind of conformal antenna that does not suffer this image current degradation is the conformal permeable antenna because it radiates using true magnetic currents (dB/dt). Instead of degrading their performance, the image effect increases the apparent volume of these antennas. Low-profile conformal permeable antennas (1/40th to 1/200th of the wavelength thick), exhibiting extraordinary GBWP, have already been demonstrated.Initially developed and demonstrated in a series of DoD funded programs over the last decade, the second generation of these antennas is now the subject of ongoing work in ONR#s LOCM-UP program. But there are two obstacles preventing pervasiveuse of this technology in DoD: (a) the high cost of the permeable material and (b) the high input impedance of the antennas.(a)The present material of choice, used in demonstrating VHF-UHF SATCOM permeable antennas, is a specialty alloy (CZN) microwave-sputtered in vacuum onto a Kapton substrate. Those prototype antennas typically use $20,000 worth of this material. (b)Currently, the antenna engineer is faced with the problem of matching a complex impedance function in the 1500 ohms range down to the conventional 50-ohm standard of communication systems, over bandwidths as large as 10:1.Accordingly, our objectivesare: (a) Identify and validate a viable low-cost electrochemical deposition route to produce equivalent materials. (b) Demonstrate that next generation permeable antennascan be constructed with input ports intrinsically matched to 50 ohms while still preserving their high GBWP. Using a combined computational and experimental effort, we will evaluate: (a) materials and processes amenable to aqueous chemistry that could yield equivalent permeability performance at 40% of the cost and possibly as low as 10% of the cost, (b) hybrid permeable antenna topologies with compact, high-power, matching network components that could lead to permeable antennas with standard-impedance feed ports over the entire band. Success in the proposed effort will advance the technology toward higher Technology and Manufacturing Readiness Levels to provide DoD with a conformal antenna technology that maximizes survivability, while supporting broadband, multi-function, resilient RF communication systems.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jun 13, 2024
- Source ID
- N000142412382
Entities
People
- Rodolfo Diaz
Organizations
- Arizona State University
- Office of Naval Research
- United States Navy