Ground Penetrating Radar Enabled by High Gain GaAs Photoconductive Semiconductor Switches
The ability of high gain GaAs Photoconductive Semiconductor switches (PCSS) to deliver fast risetime, low jitter pulses when triggered with small laser diode arrays makes them suitable for their use in ultrawide bandwidth (UWB), impulse transmitters. This paper will summarize the state-of-the-art in high gain GaAs switches and discuss how GaAs switches are being implemented in a transmitter for detection of underground structures. The advantage of this type of semiconductor switch is demonstrated operation at high voltages (100 kV) and repetition rates (1 kHz) with the potential for much higher repetition rates. The latter would increase the demonstrated average powers of 100 W to 1 kW and higher. We will also present an analysis of the effectiveness of different pulser geometries that result in transmitted pulses with varying frequency content. To this end, we have developed a simple model that includes transmit and receive antenna response, attenuation and dispersion of the electromagnetic impulses by the soil, and target cross sections.
KeywordsGround Penetrating Radar Sandia National Laboratory High Repetition Rate Voltage Waveform Laser Diode Array
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