Method and system for testing conversion losses of terahertz mixers capable of eliminating influence of radio frequency sources

A system for testing conversion losses of terahertz mixers capable of eliminating the influence of radio frequency sources, comprising a mixer to be tested and at least two reference mixers;

• all the mixers being grouped in pairs, and in each group, a signal with a first preset frequency and a first preset power is input at an intermediate frequency port of a first mixer;
• the signal is up-converted through the first mixer and then is output to a radio frequency port of a second mixer through a directional coupler, after the second mixer performs down-conversion, a first output power with a frequency same as the first preset frequency being obtained;
• wherein, the up-conversion and the down-conversion comprise the following steps:
• in the each group, a first microwave signal source provides the signal with the first preset frequency and the first preset power, and the signal is input through the intermediate frequency port of the first mixer and up-mixed with a first local oscillation signal generated by a second microwave signal source and a first local oscillation link to generate a mixed signal with the first preset frequency;
• the mixed signal is fed in through an input port of a directional coupler, then is fed to a radio frequency port of the second mixer through a coupling port, and then is down-mixed with a second local oscillation signal generated by a third microwave signal source and a second local oscillation link;
• obtaining a relationship between the first output power and the first preset power and losses of two mixers in the each group;
• wherein, the relationship is defined as a sum of the losses of the two mixers in the each group is equal to a different value between the first output power and the first preset power of a corresponding group, the following formulas:
• CL_A+CL_B=PIF_IN_AB−PIF_OUT_AB,
• CL_C+CL_B=PIF_IN_CB−PIF_OUT_CB,
• CL_A+CL_C=PIF_IN_AC−PIF_OUT_AC,
• wherein, CL_A, CL_B and CL_C respectively are the loss of the mixer to be tested and the at least two reference mixers;
• PIF_IN_AB, PIF_IN_CB and PIF_IN_AC respectively are the first preset power of the corresponding group;
• and, PIF_OUT_AB, PIF_OUT_CB and PIF_OUT_AC respectively are the first output power of the corresponding group;
• and
• the loss of the mixer to be tested is obtained according to the relationship obtained from the each group.