Solid-State High-Efficiency Radar Transmit Module

The flight capability of Unmanned Aerial Systems (UASs) is limited by many factors, especially power consumption of the on-board radar. Low-efficiency operation requires additional aircraft weight, more prime power, and effective heat removal. These impacts are expensive since propulsion and power generation are principal cost drivers.

The need for airborne stealth is driving future UASs to be small, light, and capable of high-altitude flight and prolonged flight time. This is currently prevented by UAS radar transmitters that can only operate at 20-30 percent efficiency, forcing on-board power generators to be large and heavy. Having a highly efficient power amplifier would reduce the system power requirement and substantially improve flight and radar performance (i.e., greater “up-time,” decreased fuel consumed, less heat generated, etc.). The technologies developed under this program are intended to significantly improve radar transmit module efficiency without sacrificing size and weight.

C-band Power Amplifier

This module was designed to achieve the highest possible efficiency at C-band. The solution is a super-compact MMIC with the lowest weight possible. The amplifier can operate CW as a MMIC or pulsed as a module. This circuit will be flight testing in June 2013.

Optimization Priorities:

• Size
• Output power
• Efficiency

C-band Low Noise Amplifier

This module is intended for use in a “sense and avoid” radar aboard an aircraft flying though a hostile electrical environment. Low noise amplification is needed to improve visibility without sacrificing the high-power survivability necessary for robustness. This amplifier will be used with the C-band power amplifier to complete the RF front end.

Optimization Priorities:

• Survivable power
• Noise
• Size

UHF Power Amplifier

This module delivers 400-600 W (depending on drain voltage) pulsed power from 400-450 MHz with 5070% efficiency. The C-band amplifiers use a similar design strategy, but at higher frequency and lower power. Unlike the C-band circuits, this prototype module was not optimized for size or bandwidth.

Optimization Priorities:

• Output power
• Efficiency
• Pulsing

Balanced Solution:

Design and deliver GaN power amplifiers that operate across two bands (UHF and C-band) with maximum efficiency. Form factor and robustness must be suitable for airborne platforms. Circuit technology should demonstrate scalability in both frequency and power.