The Department of Defense, specifically the United States Air Force, is seeking proposals for the development of a Conformal, Agile, Beam-Steering High Power Microwave Antenna under the SBIR program. The objective is to create an S-band, high power, frequency-scalable, steerable, and lightweight antenna capable of handling peak power levels exceeding 100 MW, with a focus on applications in directed energy weapons for ground-based or air-based missions. This initiative is critical for advancing high power microwave technology, emphasizing the need for extensive modeling, simulation, and prototype testing to meet stringent performance parameters. Interested parties should prepare to submit their proposals by June 25, 2025, with the opportunity details available on the official DOD SBIR website.

## Description

The performance of this direct to Phase II should include extensive modeling/simulation/theory of antenna and antenna feed that demonstrate ability to meet topic objective including scalability of design to different frequencies. Use of full-wave EM software such as HFSS, CST, and ICEPIC, is encouraged. For breakdown and power handling limits simulations should show fields which correspond with known models for breakdown (e.g. Kilpatrick criterion) and published dielectric breakdown and flashover strengths. Software such as SPARK3D may also be useful in this regard. For anything exceeding such limits, breakdown mitigation techniques can be proposed. Following design stage, it is also required that a prototype antenna be fabricated and tested to demonstrate key performance parameters. Antennas can be evaluated at AFRL facilities to demonstrate power handling capabilities. Those advancing to Phase III must have demonstrated a functional high power antenna or have a path forward to fix issues encountered in Phase II. Refinements can include design of control electronics to handle high power microwaves, polarizers, optimization to increase bandwidth, and improvements for managing shock and vibration. In Phase III antennas will need to refined and be scaled to operate at high frequency. Beam steering antennas arrays must be demonstrated with low side/grating/back lobes.

## Objective

Deliver an S-band high power, frequency-scalable, steerable, lightweight, conformal antenna. This capability would significantly advance the state-of-the-art of high power microwave antennas by taking advantage of advances in antennas for communication and adapting them to the extreme power handling requirements of directed energy weapons. Applications could involve ground-based or air-based missions. A primary consideration will be power handling. The antenna must be able to perform with high peak power (&gt;100 MW) and should also be able to operate at moderate average power (~ kW). Designs which can maintain these power levels even when scaled to high frequency bands, such as Ku-band, will be prioritized. Peak power density should meet or exceed 200 MW/m^2. Beam acceleration should be on the order of 100 degrees/s^2 with beam velocity exceeding this value. The goal is to quickly find track and maintain power on moving targets. This will also require wide angle steering with &gt;60 degrees off of boresight desired. Meeting these requirements could involve use of electronic or mechanical beam steering. High gain (30 dBi minimum) is desired and gain loss at wide angles should be minimized, e.g. follow a cosine distribution where loss is only owing to projected area decrease with angle. Gain will be evaluated against antenna size and ability to array the antenna &ndash; i.e. how large can a single antenna be scaled and how much gain is lost if the antenna must be arrayed to achieve high gain. Side/grating/back lobes should be minimized. Antennas should have switchable linear polarization or circular polarization. High fractional bandwidth (&gt;10%) is desired as a secondary attribute. 

## Phase I

Phase 1 awardees should demonstrate through theory and simulation and/or prototype an S-band antenna design which can meet the high performance requirements of the topic objective (frequency-scalable, steerable, lightweight, conformal). Key requirements include gain as a function of beam steering angle, antenna acceleration/deceleration and max velocity, polarization. Side/grating/back lobes should be minimized. The antenna should be reasonably amenable to high power operation in at least the MW regime (e.g. designs based on architectures such as microstrip that are known to be low power handling should not be considered unless a clear power handling strategy is given). Quarterly reports should be sent to AFRL and a final report should be written to include antenna design and verification of all required/key performance parameters including raw data, standard operating procedures, and analyses of experiments vs. simulation/theory.

## Phase II

Phase 2 awardees should procure necessary materials to design, fabricate, and test antennas. Experiments should be performed to demonstrate key performance parameters including gain as a function of beam steering angle, antenna acceleration/deceleration and max velocity, polarization. Side/grating/back lobes should be characterized. Through theory/simulation/experiment it should be demonstrated that the antenna and feed either can or can be reasonably expected to meet power handling requirements. Quarterly reports should be sent to AFRL and a final report should be written to include antenna design and verification of all required/key performance parameters including raw data, standard operating procedures, and analyses of experiments vs. simulation/theory. A plan for Phase III should be provided.

## Phase III: Dual Use Applications

Phase 3 awardees must build a high power antenna as outlined in Phase 2 and the topic description with all breakdown issues resolved. This antenna will include refinements including high power motor controls and ability to polarize beam arbitrarily across steering angles. Antenna should be tested for shock and vibration performance. Arrays of 2 or more antennas shall be demonstrated exhibiting low side, back, and grating lobes with emphasis on key performance parameters including maximum power handling (peak and average) and gain and beam agility to wide angles. Designs should be provided which demonstrate ability to scale to higher frequencies (preferably up to Ku-band) without breakdown through use of modeling and simulation and comparisons to previously determined power/field handling limits on S-band design. Contractor will work with DoD and other industry partners to identify more applications of technology including electronic warfare, radar, and communications.

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