Precision coaxial airlines and waveguides are used as in-situ impedance standards for reflection measurement over extremely wide frequency spans. Tedious visual data interpretation is replaced by digital data reduction. Intrinsic limitations of bridges or directional couplers are virtualy eliminated. UHF-through-millimeter measurements can be made witb reflection-coefficient accuracy limits of 3-30 × 10-4 depending on the physical tolerances of the reference lines.

Calculable Physical Impedance References in Automated Precision Reflection Measurement

Broadband millimeter coaxial components, including a new connector are used to configure an accurate automated scalar network analyzer system with continuous coverage from 10 MHz to 40 GHz.

Development of Broadband Coaxial Components for a 0.01 to 40 GHz Measurement System

Coaxial components including a new connector system (the W connector), couplers, switches, terminations and waveguide to coax adapters, were used to configure a VNA with continuous coverage from 0.04 to 110 GHz. Wafer probes covering the same range are also described. >

Development of broadband coaxial components for a 0.04 to 110 GHz measurement system

The precision swept frequency reflectometer uses a precisely dimensioned coaxial air-line or waveguide of suitable length for the frequency resolution required as an in situ impedance reference. The unknown impedance at the far end of the above reference creates a rotating unknown reflection phasor at the near or measuring device end of the line during swept frequency measurement. A waveguide reflection measurement is described by Hollway and Somlo and the coaxial arrangement by Lacy and Oldfield.

Precision Automated Reflectometer Using Air-Line Spans UHF through Millimeter Ranges References

The conventional error analysis for the terminations was derived from the ripple techniques [1] and [2], and by using the scalar network analyzers. Since the vector network analyzers become available and affordable to more users, there is a need to adopt a new error analysis based on the international standards. A careful review of error analysis procedure based on the requirements of the ISO Guidance for Expression of Uncertainty in Measurement (GUM) was conducted for the Type N and V connector terminations.

Uncertainty analysis for 65 GHz terminations calibrated with vector network analyzers

A system is presented which provides a decade improvement in voltage reflection coefficient measurement accuracy over the range of 0 to 50 dB return loss. The technique separates the unknown from the error signals. Two methods using a combination of old and new techniques are presented Error Averaging and Magnified Swept Sensor. The basic ingredients are precision airline and directional bridge. A mathematical review of the old and the new reflectometer methods will be included.

W. Oldfield

Papers

A High Precision Swept Rf Reflectometer System in Coaxial Line