VNA frequency extenders cover waveguide bands from 50 to 220 GHz. They are compatible with many VNAs that provide external LO and IF signal access. Standard models come as a pair to support full 2-port S-parameter testing. RF test power is adjustable over a 20-dB range. Typical measurement dynamic range is 110 dB. 

 https://www.eravant.com/products/vector-network-analyzer-extenders