Extremely High Frequency Transmitter for Radar Applications

OUSD (R&E) MODERNIZATION PRIORITY: General Warfighting Requirements (GWR) TECHNOLOGY AREA(S): Weapons, Sensors 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: Design, build, demonstrate, and deliver a high power amplifier (transmitter) operating at an atmospheric transmission window towards realizing short-range Radar applications above 100 GHz. DESCRIPTION: Robust short and medium-range air surveillance is an essential capability for the security of critical assets and areas as unmanned aerial vehicles commonly known as drones are gaining increased attention in various fields due to their vast application potential. Several air surveillance capabilities in the form of traditional Radar systems operating at X-band and below as well as active and passive infrared and optical systems are tasked to solve the issue of providing a robust air picture, with limited success in a stressing and congested environment. The upper region of the extremely high frequency millimeter wave band is loosely defined for frequencies between 100 and 300 GHz. This band has shown promising potential for imaging and high-resolution Radar applications. However, those have been limited to very short ranges of centimeters to meters due to the lack of a transmitter that can amplify a waveform in this band to meaningful levels for Radar applications. Other major parts of a high frequency millimeter wave Radar systems exist to include continuous wave and pulsed signal generators, frequency mixers, antennas, and super heterodyne receivers. What remains is the high power amplifier to complete the hardware requirements for a Radar system. It is the goal of this project to push the technology of high frequency millimeter wave Radar to instrumented ranges that are useful for cued air surveillance applications and to produce another frequency band for meeting the challenge of short-range air surveillance. In particular, a high power amplifier operating in a propagation window bounded between 100 and 300 GHz (W-band is purposefully excluded to foster technology development at extremely high frequencies above 100 GHz) is needed for ranging applications reaching 20 km for a 1 square meter target. Initial models suggest that an amplifier with peak output powers of tens of Watts (50 W objective, 15 W threshold) is required assuming high gain antennas (60 dBi) are used. In order to promote multiple approaches, such transmitter may operate in continuous wave mode and/or pulsed mode with a minimum duty cycle of 5%. Associated waveform parameters (pulse width, instantaneous bandwidth, frequency tunability, pulse repetition frequency, harmonics, spurs, etc.) are to be defined by the proposer but should meet the requirements for Radar applications (e.g. an instantaneous bandwidth of 10% is desirable). PHASE I: Design a high power amplifier operating in an atmospheric transmission window between 100 300 GHz (e.g. 140 GHz, 220 GHz). The amplifier solution needs to be compact to allow for transport and use outside a laboratory environment. The delivery is a detailed and technically sound solution for building proposed transmitter within the schedule and budgetary constraints of a Phase 2 award. The transmitter shall accept and amplify a signal provided by an external signal generator with output power of 0 dBm. The transmitter shall output the signal in the form of a rectangular waveguide. PHASE II: Construct, demonstrate, and deliver the high power amplifier described above. The transmitter shall allow for operation with general AC power supply equipment (e.g. 120V single phase, 208V 3 phase shore power or generator power), meaning the DC power supply has to be included with the transmitter build. Forced air and liquid cooling are both acceptable. PHASE III DUAL USE APPLICATIONS: High power transmitters operating above 100 GHz will open a commercial sector in this frequency region for ranging and high bandwidth communications. With the proliferation of drone usages in urban areas and the ever-increasing need for high bandwidth wireless communications to connect commercial and residential areas and push the availability of high-speed internet to rural areas, high power extremely high frequency millimeter wave signal generation is needed now. REFERENCES: High Frequency Integrated Vacuum Electronics (HiFIVE) https://www.darpa.mil/program/high-frequency-integrated-vacuum-electronics; Sub-millimeter wave receivers https://www.vadiodes.com/en/products/custom-receivers Backward wave oscillator for high power generation at THz frequencies SPIE Proc. VIII, Terahertz Emitters, Receivers, and Applications VIII (2017). Performance improvement of a sub-THz traveling-wave tube by using an electron optic system with a converging sheet electron beam Elsevier, Results in Physics, Vol 12, 799-803 (2019). KEYWORDS: millimeter wave, radar, terahertz, sub-millimeter wave, transmitter, high power amplifier