How do I make spectrum analysis measurements on signals above 110 GHz using a PSA Series Spectrum Analyzer (E4440A, E4446A, E4448A)?

The PSA with option AYZ enables the use of external mixers. Mixers above 110 GHz use the same port for LO in and IF out. In order to connect these types of mixers to the PSA, a diplexer is required. The purpose of the diplexer is to split the IF out so it can be connected to the IF port and combine the LO on to a single line connected to the mixers LO/IF line. A harmonic of the LO from the PSA mixes with the incoming RF and an IF signal is generated. The IF is low pass filtered in the diplexer and sent to the IF port of the PSA.

External harmonic mixers above 110 GHz generally require biasing. The PSA supplies bias current in the range of +/- 10 ma. This bias current is supplied on the IF port.