A general purpose two-channel Frequency modulated continuous wave (FMCW)-sensor in E-band is extended to a digital-beam-forming (DBF) system. The hardware extension contains a transmit multiplexer, which allows switching of the (DBF) transmit signal of the sensor to any of 32 linearly arranged waveguide antennae. To maintain the spatial sampling condition by λ/2 element distance, the antenna ports are arranged in the E-plane. The ports can directly radiate or serve as primary radiators of a cylindrical dielectric lens focusing in the H-plane. By realizing the hardware extension based on a metal-backed substrate, some novel radio frequency (RF) structures became necessary. One of these structures is a special twisting microstrip-to-waveguide-transition to connect the switching matrix to waveguide ports arranged in the E-plane. Key elements of the multiplexer are commercially available pin-diode-based MMIC-switches in microstrip technology. To lower the inductance of the interconnects, they are embedded in cavities in the metal-backed RF-substrate. RF interconnects between the sensor and the extension are all done with waveguide ports. Further interconnects between the module and the extension are low-frequency or digital and are led via cables and removable plugs. Both module and extension can be powered separately. This gives an easily mountable extension for making a two-dimensional (2D) DBF sensor out of a 1D FMCW-sensor.