Attenuation of Spurious Impulses from an Ultra-Wideband Radar: A High-Speed Switch for the Synchronous Impulse Reconstruction (SIRE) Frontend

Report No. ARL-TR-5750
Authors: Gregory Mazzaro, Marc Ressler, Gregory Smith, and Francois Koenig
Date/Pages: September 2011; 36 pages
Abstract: The performance of ultra-wideband (UWB) radar systems suffers from reflections between frontend components caused by impedance mismatch. The Synchronous Impulse Reconstruction (SIRE) radar built by the U.S. Army Research Laboratory (ARL) is no exception. While most of the radio frequency (RF) energy in each impulse is transmitted by the radar as desired, a portion of the RF energy reflects within the radar frontend. Undesired impulse echoes arrive back at the transmit antennas and are emitted from the radar. These undesired transmissions reflect from the radar environment and produce echoes in the radar image. The proposed solution for eliminating these echoes is to dissipate impulse reflections in a matched load before they are emitted. A high-speed switch directs the desired impulse to the antenna and redirects the undesired reflection from the antenna to a matched load. This report reviews the current SIRE frontend design and describes the solution for eliminating the echoes. The consequences of inserting each portion of the new circuit into the radar frontend are explained. Measurements on the new frontend show an attenuation of the undesired impulse transmissions of more than 18 dB at the expense of an attenuation in the desired impulse transmission of less than 3 dB.
Distribution: Approved for public release
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Last Update / Reviewed: September 1, 2011