Virginia Diodes Inc (VDI), a spin off from research done at the University of Virginia (UVA), manufactures test and measurement equipment for mm-wave and THz applications, including millimeter-wave diodes, terahertz devices, integrated components and systems operating from 18 GHz to over 3 THz. These products include a Vector Network Analyzer, Spectrum Analyzer and Signal Generator Extension Modules that extend the capability of high performance microwave measurement tools to higher frequencies. The company's products are widely used in radio astronomy, millimeter-wave spectroscopy, compact radar, atmospheric physics, plasma diagnostics and in a wide range of other scientific instruments. The products are based on a proprietary GaAs Schottky diode technology that enables them to operate at frequencies beyond the standard commercial microwave and millimeter-wave bands. The firm aims to increase the usefulness of the terahertz region of the electromagnetic spectrum for scientific, military and commercial applications.