New calibration techniques for one-port measurements using a computer-corrected network analyser

The thesis presents three new computer correction methods for measuring immittances and reflection coefficients using an automatic network analyser. The first correction method called the "Three Short Circuit Correction Method" was invented to overcome the difficulty of measuring components embedded in microstrip or in confined environments where sliding matched terminations required by normal correction methods cannot be used. With this new method, error correction is carried out based on calibration measurements produced using three unevenly spaced short circuits. This method was subsequently published in the I.E.E. journal "Electronic Letters" of 22nd March, 1973. The second correction method using four evenly spaced short circuits was introduced to overcome the difficulty of accurately specifying electrical lengths in microstrip or in a transmission line with non-hmnogenous medium. The third correction method was evolved to overcome the practical difficulties of constructing good short circuits within microstrip lines. With this method, direct knowledge of the terminations of the calibration standards is unecessary. Rigorous theoretical derivations for the last two correction methods have been published in the I.E.R.E. journal "Radio and Electronic Engineer" issue of May, 1978. Detailed measurement results and comparisons of the different types of correction measurements have been published in the "Microwave Journal" issue of June, 1978. The last two correction methods also provide a means of measuring the attenuation and phase changes of transmission lines, and the effective dielectric constant of a nonhomogerous line may be calculated if its physical length is known. Comparative measurements carried out using the new correction systems as opposed to the older established correction syst.ems are included in this thesis. They agree most favourably. Results obtained using a.ny of the new correction systems have shown that measurement accuracies of + 0.5% with a confidence level of 99% are attainable. These results have been confinned by statistical data obtained from repeated measurements (100 in some cases) of an accurately defined test standard