Experimental research on passive intermodulation effect of microstrip lines

In this paper, a preliminary experimental research on passive intermodulation (PIM) effect of microstrip lines is conducted using customized PIM analyzer. First, various microstrip lines of 50Ω characteristic impedance with different lengths are designed and fabricated on microwave dielectrics. Then, the microstrip lines are connected to the PIM analyzer through low PIM silver plated N type coaxial connector and their PIM products are measured. Measurement results show that the 3rd PIM products increases about 2.7 dB when input carrier increases 1 dB; PIM products tend to decrease with increasing carrier frequency; PIM products increases with the length of microstrip lines; microwave dielectrics also has notable effect on PIM products. The obtained results can provide reference for design of high performance microwave integrated circuits.