2X-thru

s11 and s21:hows the ADS simulation of 2X-thru, where the S2P files of fixtures A and B are introduced to observe whether fixtures A and B are symmetric. It can be seen from the insertion loss S21 and return loss S11 of the 2X-thru simulation in Fig. 5(c) that the insertion losses of fixtures A and B almost coincide, but the return loss is not completely coincident because of the discontinuous impedance of the transmission line of fixtures A and B at the connection between the coaxial connector and the PCB. In Fig. 5(c), T11, the impedances of fixtures A and B at the interface of the SMA to the microstrip line are 55.15 and 52.24 Ω, respectively, with a difference of 2.91 Ω. Owing to process instability and errors in circuit fabrication, there are large differences in the S parameters of fixtures A and B, which may lead to inaccurate and unsatisfactory test results. In the actual production process, completely symmetric fixtures A and B could not be fabricated; therefore, errors between them were inevitable. In addition to the unavoidable factors, the 2X-thru structure designed in this study is symmetrical and can provide significant reference data for testing.