Improved Propagation Constant Determination Using Two-Line Measurements

Accurate determination of the propagation constant (γ) in uniform microwave lines is critical but challenging due to the requirement for complex calibration and susceptibility to measurement noise. In order to overcome these limitations, a new objective function has been derived for improved propagation constant γ measurement of uniform lines with symmetric reflections through calibration-free line–line measurements. Well-known methods in the literature on the determination of propagation constants with reflection asymmetry and non-reciprocal behavior structures are investigated and compared. To this end, mathematical derivations related to theory of microwave networks are validated by measurements in microwave frequency range X-band (8.2–12.4 GHz). Its advantage relies on the fact that it uses a term which is in the product form of determinants of two characteristic terms, whose value is close to unity both in theory and experiments. Eigenfactor (complex exponential) and γ measurements of an X-band uniform (empty) waveguide section with symmetric reflections were carried out to validate our proposed formalism.