High-Sensitivity Transceiver for Airborne Ultra-Wideband Radio Echo Sounding of Polar Regions

This paper presents the design and development of a high-sensitivity ultra-wideband radar for sounding and imaging 5-km thick polar ice. The design is optimized to detect internal layers in ice from the surface to the bed with fine resolution. The radar consists of 8 transmitters and 16 receivers. Each transmit/receive module is designed to operate either as a standalone system or as a channel of multi-channel radar. Each subsystem is designed and optimized, and then integrated. Each transmitter's output power is 53 dBm and operates over the frequency band of 170 - 470 MHz. A push-pull amplifier configuration is used in the transmitter chain to reduce the second harmonic distortion of the transmitted chirp. A high-power, high-speed PIN diode transmit/receive switch is also designed to operate the radar with a single antenna array. The High-power switch cascaded with a low-power CMOS switch provides 80 dB isolation between the transmitter and receiver. The receiver subsection is designed to provide optimal performance with the digital subsystem. The receiver offers a 20-dB gain over the frequency of operation. Based on laboratory tests, the radar will have a loop sensitivity of about 250 dB for airborne measurements.