Extremely High Frequencey Transmitters for Radar Application.

There are unmet needs for high power, extremely high frequency (EHF) power amplifiers and transmitters. Vacuum electron devices (VEDs) are critical components for DoD systems that are in of high power, high frequency (wide bandwidth), and high efficiency. The technology continues to be pushed to higher frequency for radar, communications and imaging among other applications. 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. This SBIR project calls out the need to push the power amplification into the upper region of the extremely high frequency millimeter wave (MMW) band of frequencies between 100 and 300 GHz to, for example, enable EHF MMW Radar to finally reach 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. To address this need, we are developing a 225 GHz, targeted 50 Watt with > 15 Watt, close to 10% instantaneous bandwidth (BW) microfabricated compact traveling wave tube (TWT) amplifier. Operation at EHF MMW poses significant challenges as the available power from both solid state and VEDs dramatically decreases with increasing frequency especially at MMW frequencies and above. At the high MMW frequency range, conventional construction of VEDs including TWTs is an intricate labor-intensive low yield process which significantly increases the cost and duration of the device design, build, and test cycle. Unlike conventional approaches, the compact EHF MMW high power TWTs we are developing are based on microfabricated/additive manufacturing of quasi-optical spatial power combining (QOPC) arrays of beam-wave interaction structures. We use advanced manufacturing including additive manufacturing (including 3D-Printing) and microfabrication to support high power EHF applications. Our solid state vacuum deviceTM (SSVDTM) microfabrication techniques and technologies including both batch processing of the radio frequency (RF) interaction circuits and microfabrication as the production "tools" of the RF interaction circuit at frequencies up to W-band and, now, for this SBIR, 225 GHz TWT amplifiers. Although highly challenging, based on the successful Phase I feasibility demonstration, we are extremely confident that this 225 GHz TWT high power amplifier can be successfully manufactured. We shall provide a complete turnkey 225 GHz transmitter including the power supply (both AC to DC and DC to DC versions). This Phase II work will produce significant advancements in sub-THz and THz power amplifiers and advanced VED manufacturing capability improvements in power, bandwidth, reliability, efficiency, and manufacturability as well as advancing the science and technology base for the next generation of VEDs for sub-THz.