A low cost 10.0-11.1 GHz X-band microwave backscatter communication testbed with integrated planar wideband antennas

We present a low cost X-band microwave backscatter communication testbed incorporating integrated planar wideband bow-tie antennas. This testbed leverages low cost silicon germanium (SiGe) integrated circuits intended for the satellite television market to provide an experimental capability for backscatter experimentation in the 10.0 GHz to 11.1 GHz band. The integrated wideband bow-tie antennas have a 10 dB return loss bandwidth of 9.63-13.15 GHz and a gain of 6 dBi. The transmitter consists of a single-chip frequency synthesizer and buffer amplifier with an output power of -2 dBm. The receive downconverter consists of an integrated LNA, mixer, and LO frequency synthesizer, with an RF frequency range of 10.0 GHz to 13.0 GHz and an IF frequency range of 250 MHz to 3250 MHz. The downconverter's measured conversion gain is 36 dB with a noise figure of 7 dB. The IF signal processing leverages a Universal Software Radio Peripheral (USRP) to support arbitrary backscatter modulation schemes such as ASK, PSK, or QAM backscatter with an IF bandwidth up to 50 MHz. We found good agreement between the measured and simulated free-space path loss at ranges of up to 4.1 m in a laboratory environment, and demonstrate the use of this testbed in a BPSK backscatter configuration at a rate of 10 Mbps.