N242-090 TITLE: Low-Cost, High-Power Microwave Switches for Radar and Electronic Warfare (EW) Applications

OUSD (R&E) CRITICAL TECHNOLOGY AREA(S): Advanced Materials; Microelectronics

OBJECTIVE: Design, optimize, and fabricate prototypes for a low-cost, low-loss, high-power microwave switch with fast-switching speeds over large instantaneous bandwidths for radio frequency (RF) surveillance and Electronic Warfare (EW) applications.

DESCRIPTION: While phased array systems with analog or digital phase control at each element provide a highly flexible means of shaping transmit or receive antenna patterns, the per-element cost remains high for these systems, especially when tailored toward stringent Naval requirements. These requirements range from demanding radiated power levels, high system efficiency, coexistence with other emitters and receivers, operation over very wide bandwidths, and multi-function capabilities. On top of this, there is a growing need for adaptive array systems with low SWAP-C for surveillance, electronic warfare, and modern communication systems. To meet these objectives, some phased array approaches are looking toward tunable circuitry solutions that are applied after the high-power microwave source, rather than before.

Some of these solutions are implementing high-power handling output tuners that actively control the scan impedance of an array, improving overall system efficiency [Refs 1, 2], and investigating "reflectarrays" or "intelligent reconfigurable surfaces" [Ref 3]. Phased array systems employ a corporate feed for RF power distribution over small subarrays also have a need for high-power phase shifters. Ferrite phase shifters have historically had a role in this area, but the high losses have made these architectures undesirable.

Several types of RF switches, such as solid state switches (PIN diode, FETs), electromechanical switches (waveguide, coaxial, MEMS), semiconductor switches with new materials (GaN, SiC), photoconductive semiconductor switches (PCSS), and plasma switches (Gas Discharge Tube), have been investigated, each with various strengths and weaknesses with respect to insertion loss, isolation, linearity, switching speed, power handling, or wideband performance [Refs 4, 5, 6, 7]. Compromises between these metrics are limiting the uptake of high-power RF switches.

To that end, the Navy is seeking novel methods of designing and producing low-cost, high-power microwave switches with minimal compromises in other key performance parameters for radar and electronic warfare applications. The proposed approach shall provide significant performance improvement with respect to power handling, tuning speed, efficiency, and linearity, while reducing unit cost to enable low-cost phased array solutions for the Navy.

PHASE I: Develop a preliminary design of hardware for a novel, low-cost, high-power microwave switch that significantly exceeds the current state-of-the-art and improves the performance of current switches. Develop a design approach and produce simulated results of a high-power, fast microwave switch that meets or exceeds the following metrics:

• Operating frequency: Any one octave over 2-12 GHz (Threshold), entire 2-18 GHz band (Objective)

• Power handling (1-dB compression point) - Operative above a curve defined by the following frequency & power points:

Threshold Power: 250 W @ 3GHz // 50 W @ 10 GHz

Objective Power 750 W @ 3GHz // 150 W @ 10 GHz

• Targeted unit costs: $50/device (Threshold), $5/device (Objective)

• Insertion loss: < 1dB (Threshold), < 0.3 dB (Objective)

• Isolation: > 20 dB (Threshold), > 40 dB (Objective)

• Switching speed: 500us (Threshold), 50 ns (Objective)

• Cycles: > 3e9 (Threshold), > 30e9 (Objective)

• Linearity: Input third order intercept approximately 10dB above P1dB point.

• Duty cycle: Greater than 20% (Threshold), to CW (Objective)

Note – As with other research programs, proposed solutions may have sub-threshold performance in an area if it excels in other areas.

Prototypes and experimental testing that reduce technical or manufacturing risk are encouraged. However, the Government understands some fabrication processes are not feasible within Phase I funding, so modeling and simulation approaches are also acceptable. Lastly, provide a Phase II plan that includes the estimated performance of prototype switches to be fabricated in Phase II.

PHASE II: Produce a prototype or set of prototypes of the Phase I switch design. Laboratory based testing shall be completed under the Phase II effort to demonstrate that the technology meets performance metrics set at the end of Phase I. Efforts should characterize devices against metrics set forth in Phase I, identify and iterate on designs to improve performance, and provide a recommended path for higher-volume production.

PHASE III DUAL USE APPLICATIONS: Design, build, and deliver higher level subassemblies including the new switching technology, with assistance from the Navy. Possible subassemblies may include high-power phase shifters, low-loss antenna tuners, or switch-tuned filters. These efforts will target components and subassemblies that support both DoD applications (e.g., phased array radar or electronic warfare systems), and commercial applications (e.g., adaptive arrays for high power 5G/6G cellular base stations).

REFERENCES:

1. Vander Missen, Zach et al. "Plasma Switch-Based Technology for High-Speed and High-Power Impedance Tuning." 2021 IEEE 21st Annual Wireless and Microwave Technology Conference (WAMICON). https://ieeexplore.ieee.org/document/9443612
2. Calabrese, Caleb et al. "Fast switched-stub impedance tuner reconfiguration for frequency and beam agile radar and electronic warfare applications." 2020 IEEE International Radar Conference (RADAR). https://ieeexplore.ieee.org/document/9114834
3. Rossanese, Marco et al. "Designing, building, and characterizing RF switch-based reconfigurable intelligent surfaces." Proceedings of the 16th ACM Workshop on Wireless Network Testbeds, Experimental evaluation & Characterization, October 2022, pp.69-76. https://dl.acm.org/doi/10.1145/3556564.3558236; https://doi.org/10.1145/3556564.3558236
4. Iannacci, Jacopo. "RF-MEMS technology for high-performance passives." IOP Publishing Ltd., 2022. https://iopscience.iop.org/book/mono/978-0-7503-4199-8.pdf
5. Fisher, Alden; Jones, Thomas R. and Peroulis, Dimitrios. "Design and Optimization of a High-Power Solid-State Plasma RF Switch." IEEE Transactions on Microwave Theory and Techniques, 01 August 2023, pp. 1-14. https://ieeexplore.ieee.org/document/10199132
6. Loubriel, Guillermo M. et al. "Photoconductive semiconductor switches." IEEE Transactions on Plasma Science, Volume 25, Issue 2, 1997, pp. 124-130. https://ieeexplore.ieee.org/document/602482
7. Semnani, Abbas; Macheret, Sergey O. and Peroulis. Dimitrios. "A quasi-absorptive microwave resonant plasma switch for high-power applications." IEEE Transactions on Microwave Theory and Techniques, Volume 66, Issue 8, 2018. pp. 3798-3806. https://ieeexplore.ieee.org/ielaam/22/8425664/8361494-aam.pdf

KEYWORDS: Microwave switches, antennas, phased arrays, phase shifters

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