Characterization of superconducting microwave devices in frequency domain at millikelvin temperatures. The devices are measured in transmission or in reflection, across the frequency band 4-8 GHz. The methods include vector network analysis and spectrum analysis. A cryogenic temperature-variable resistive noise source is available. DC lines for biasing are available. The setup has high throughput (5 devices per cool-down), but only rudimentary calibration of the S-parameters is available (bypass transmission reference, open circuit reflection reference). The customer provides a microchip with a pre-determined size and arrangement of ports. Alternatively, the customer provides a packaged and connectorized RF module that fits inside the available shield.