Air-line Impedance Standards Research Articles

Extended cross-ratio reflection correction at microwave frequencies using waveguide air-lines

It is shown that the extended cross-ratio method of correction of the complex reflection coefficient /spl Gamma/ is applicable not only in coaxial lines but also in waveguides at microwave frequencies when precision waveguide sections of well-defined cross dimensions are used as reference air-line impedance standards. A detailed uncertainty calculation which includes the influence of waveguide imperfections is given. Small total expanded uncertainties less than 0.002 for |/spl Gamma/|/spl les/0.25 can be achieved.

Determination of mismatch factor with RF power calibration using air-line impedance standards

A method to calibrate a coaxial rf power meter by comparison with a standard power meter is described, the ratio of the mismatch factors being determined using two calculable coaxial air-line impedance standards. An initial investigation of the uncertainty of calibration has been made, and initial experimental results of measurements performed with the 7 mm coaxial system and for type N connectors at frequencies from 2 GHz to 18 GHz are presented.

Correction of the RF complex reflection coefficient using air line impedance standards

A simple method based on the invariance property of the cross-ratio of the bilinear transformation is described in which complex reflection coefficient values obtained with a reflectometer are traced back to calculable air line impedance standards. First experimental results obtained for various coaxial systems and frequencies up to 18 GHz are presented. >

Simple method for correction of reflection values by means of coaxial quarter wavelength air line impedance standards

If only impedance standards of low quality are available for the calibration of a reflectometer of a network analyser, a simple correct method can be applied in which complex reflection coefficient values are traced to calculable air line impedance standards. The method has been tested in experiments in 14 mm and 7 mm/N coaxial techniques.

Some Fundamental Design Principles for the Development of Precision Coaxial Standards and Components

Significant advances in the performance of precision coaxial standards and components have resulted from rigid adherence to three basic design principles: 1) incremental constancy of characteristic impedance, 2) coplanar compensation of discontinuities, and 3) control of mechanical tolerance sensitivity. The advances include dielectric supports with extremely small interface discontinuities, contacting members that are insensitive to mechanical tolerances, calculable airline impedance standards of very high absolute accuracy, nearly reflectionless terminations based on a cylindrical metal-film resistor, and adaptors between line sizes based on smooth (rather than stepped) diametral transitions. Extensions of the design principles have resulted in the introduction of closely controlled reflections provided by a novel impedance-matching tuner, broadband calibrated mismatches, and resistance-standard terminations that retain their nominal dc values to very high frequencies.