A broadband Microwave Transceiver Front-end for an Airborne Software Defined Radio Experiment


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Virginia Tech


This document describes the design, simulation, construction, and test of a wideband analog transceiver front-end for use in an airborne software defined radio (SDR) experiment. The transceiver must operate in the GSM-1800 and IEEE 802.11b/g WiFi frequency bands and accommodate beamforming. It consists of a transmitter and dual band receiver. The receiver input is fed by a helical antenna and the outputs are digitized for use in the SDR. The transmitter is fed by a complex baseband output from a Digital-to-Analog Converter (DAC) and its output fed to another helical antenna. The requirements for the transceiver were driven by a spectral survey of the operating environment and the physical and electrical limitations of the platform. The spectral survey showed a great disparity in the received power levels between the signals of interest and potential interferers. Simulations of several candidate receiver architectures showed that meeting the needs of the experiment would require a high degree of linearity and filtering. It was found that the receiver requirements could be met by a single downconversion with high order filters and passband sampling. A series of analyses determined the requirements of the individual components that make up the system. Performance was verified by simulations using measured data of the individual components and lab tests of the assembled hardware. Suggestions for improved performance and expanded operation are made.



communications, RF, Software radio