This paper describes a wideband radio channel sounder. Such a device is able to measure the complex time variant impulse response of the propagation channel. The impulse response is obtained by inversion of an optimal multisine sequence (flat spectrum, low crest factor). In standard configuration, this device is able to measure the propagation channel impulse response with a maximum bandwidth of 2 GHz in the 26 GHz frequency range. The bandwidth can be extended up to 2 GHz in UWB configuration. Up to 1 antenna can be connected to the channel sounder for the analysis of multiantenna technologies. The receiver digital part is based on a 1 Gs/s digitizer with 26 Mb embedded memory. The large memory capacity enables high measurement rates (s) without limiting the maximum number of measurement points (32768). RF and digital parts have been integrated into a VXI system. VXI systems are well suitable for the design of measurement prototypes by providing useful facilities (power supply, fan cooling, data bus, and trigger).