N241-062 TITLE: Innovative Low Profile, Foldable, High Power Microwave Antenna

OUSD (R&E) CRITICAL TECHNOLOGY AREA(S): Advanced Materials; Directed Energy (DE)

The technology within this topic is restricted under the International Traffic in Arms Regulation (ITAR), 22 CFR Parts 120-130, which controls the export and import of defense-related material and services, including export of sensitive technical data, or the Export Administration Regulation (EAR), 15 CFR Parts 730-774, which controls dual use items. Offerors must disclose any proposed use of foreign nationals (FNs), their country(ies) of origin, the type of visa or work permit possessed, and the statement of work (SOW) tasks intended for accomplishment by the FN(s) in accordance with the Announcement. Offerors are advised foreign nationals proposed to perform on this topic may be restricted due to the technical data under US Export Control Laws.

OBJECTIVE: Develop a lightweight, affordable, foldable/stowable, frequency-scalable, gain/aperture scalable, steerable, low-profile antenna design to improve the performance of High Power Microwave (HPM) weapons. The threshold Radio Frequency (RF) range of interest is 1-to-20-GHz. The antenna system must be capable of High Power use = 100 MW peak power, and waveguide fed.

DESCRIPTION: Components for HPM weapons often work well in the laboratory, but fail in the tactical environment (e.g., dirt, shock and vibration, extreme temperature, exposure to salt water). The objective of HPM weapons is generally achieved by maximizing the Radio Frequency (RF) power density (PD) (PD in units of W/m^2) at the target. PD on target depends on power handling capabilities and gain of the antenna system. A limitation on HPM weapons is achieving appropriate even gain across a large enough bandwidth while maintaining high peak power handling capabilities. The current systems, which couple to HPM antennas, utilize a waveguide output and a wide variety of high-power mode converters already exist, thus any waveguide input can be considered but fundamental modes are encouraged.

While high power antennas exist, most have not been designed with harsh military environments or lightweight steerable mounts in mind. Considerations such as materials that support lighter weights while maintaining mechanical strength to combat wind and water loads (i.e., watertight, wave slap, salt fog, etc.), foldability for storage when not in use, and precise steering to quickly engage multiple targets.

Producing high RF power density at the HPM source (in order to produce high PD at the target) will require a multi-disciplinary investigation. Electrical engineering and physics will be required to achieve the objective for high electric field (E) in the antenna input as well as the mechanical requirements needed to survive the harsh military environments. The high power and pulse repetition rate present potential for electrical breakdown in the antenna systems. The pulse duration and maximum size of the aperture can lead to reduced aperture efficiency due to pulse traversal time across the aperture. Current designs feature vacuum-insulated overmoded waveguide feeding a reflector-type antenna. Of course, innovative designs must not introduce unwanted effects; for instance, a voltage standing wave ratio (VSWR) sufficient to damage the source. An innovative design must be able to handle the stress environment of tactical employment, including reducing side lobes to minimize potential Electromagnetic Interference (EMI) to nearby assets and systems, manufacture, transport, storage, launch and operation. The evaluation of the stress environment should include, but is not limited to, shock, vibration, fatigue, water tight, wind loads, corrosion, etc.

KEY ANTENNA PARAMETERS

Will be negotiated with each proposal depending on submitted design. After award a more specific design case may be provided.

• Operating frequency in the range of interest between 1-20 GHz.

• Reliable, operating at peak power levels = 100 MW.

• Maximum possible gains for specific use cases.

• Aperture Area: 10m^2 or greater but scalable and foldable (collapsible) for stowage and transportation when not in use.

• No electrical breakdown inside the antenna, especially at or near the source.

• Waveguide fed and steerable in azimuth and elevation.

• Radome structure to account for sea-state loading, green water load, and sea spray or salt fog corrosion, water tight, etc.

• Radome structure properties specifically beneficial to SOW-negotiated frequencies.

• Compact or low profile design, to-be-determined in SOW negotiation.

• Sufficiently low side and back lobes to permit operation within and near the desired platforms or systems. This will vary but a reasonable expectation may be -30 dB from the well-defined main beam.

• Unique radome designs to reduce side-lobes to ease EMI challenges with platform integration.

Work produced in Phase II may become classified. Note: The prospective contractor(s) must be U.S. owned and operated with no foreign influence as defined by 32 U.S.C. § 2004.20 et seq., National Industrial Security Program Executive Agent and Operating Manual, unless acceptable mitigating procedures can and have been implemented and approved by the Defense Counterintelligence and Security Agency (DCSA) formerly Defense Security Service (DSS). The selected contractor must be able to acquire and maintain a secret level facility and Personnel Security Clearances. This will allow contractor personnel to perform on advanced phases of this project as set forth by DCSA and ONR in order to gain access to classified information pertaining to the national defense of the United States and its allies; this will be an inherent requirement. The selected company will be required to safeguard classified material during the advanced phases of this contract IAW the National Industrial Security Program Operating Manual (NISPOM), which can be found at Title 32, Part 2004.20 of the Code of Federal Regulations. Reference: National Industrial Security Program Executive Agent and Operating Manual (NISP), 32 U.S.C. § 2004.20 et seq. (1993). https://www.ecfr.gov/current/title-32/subtitle-B/chapter-XX/part-2004

PHASE I: Consult with ONR to identify a nominal, perhaps-hypothetical, platform-payload configuration with operational parameters, to include SWAP-C, Effective Radiated Power (ERP), parameters for pulsed RF power, mechanical stress objectives and environmental considerations.

Consult with ONR to identify potential front-end HPM source systems (e.g., including pulsed power) that shall be configured to work with the innovative antenna subsystem.

Develop design strategies, Modeling and Simulation (M&S) and experimental validation for:

• Mechanical Stress analysis

• Mechanical concept design to include steering capabilities and limitations

• Weight analysis, environmental considerations, and transportability

• High power handling capabilities

• Low probability of electric breakdown with respect to previously stated considerations

• Innovative structural design and validation without unacceptable effects such as high VSWR

• Dielectric insulation choices

• Polarization choices, including but not limited to linear polarization (horizontal or vertical) or circular-elliptical polarization

• Feed network, mode converter

Conduct initial iterations of design, M&S and experimental validation.

Provide a convincing way forward for a Phase II effort.

PHASE II: Design, build and test (at low power) the innovative antenna subsystem. Provide low-power characterization to include sidelobe characterization and steering in azimuth and elevation. Perform the preliminary work necessary to prepare for high-power testing and characterization in Phase III.

Work in Phase II may become classified. Please see note in the Description.

PHASE III DUAL USE APPLICATIONS: Support ONR to configure the antenna subsystem with a high-power HPM source. Test and characterize at high power. ONR may also dictate the location and government assets used to verify the test and characterization.

REFERENCES:

1. Balanis, Constantine A., Antenna Theory: Analysis and Design, Third Edition, Wiley Interscience, ISBN 0-471-66782-X, 2005.
2. Benford, James, Swegle, John A., and Schamiloglu, Edl, High Power Microwaves, Third Edition, CRC Press, 2019.
3. Skolnik, Merrill I. (ed) Radar Handbook, Third Edition, Mc-Graw Hill Education, February 12, 2008, ISBN-13: 978-0071485470.
4. Haddad, A and Warne, D. Advances in High Voltage Engineering, IET. ISBN 0852961588. (2004).
5. Kuffel, E. "High Voltage Engineering: Fundamentals." Pergamon, 2016. ISBN 0-7506-3634-3. https://www.amazon.com/High-Voltage-Engineering-Fundamentals-Electricity/dp/008024212X
6. Milligan, Thomas A. "Modern Antenna Design, 2nd Ed." Wiley-Interscience, John Wiley & Sons. ISBN 0471720607 (2005).

KEYWORDS: High Power Microwave (HPM) weapons, High Power Wideband Antenna, Electric Field Breakdown in an RF environment, Mechanical Structure Tolerance, Shock, Vibration and Fatigue Testing, Modeling and Simulation (M&S), Electric Polarization, Antenna Mount, Fold

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