Ryoko Kishikawa

Metrological Traceability in Waveguide S-parameter Measurements at 1.0 THz Band

We have improved the measurement uncertainty for rectangular waveguide vector network analyzer (VNA) measurements in the WM-250 (WR 1.0), 750 GHz–1.1 THz frequency band. We developed a new waveguide flange design for precise connections and dimensional measurements to establish traceability to SI in VNA measurements. This is the first such achievement to be reported using a VNA in the terahertz frequency band.

Complete characterization of rectangular waveguide measurement standards for vector network analyzer in the range of millimeter and sub-millimeter wave frequencies

This paper describes a complete dimensional evaluation technique andelectrical characterization of waveguide shims as primary standards suitable for vector network analyzer (VNA) calibration at millimeter-wave and sub-millimeter wave frequencies. The NMIJ has established techniques for dimensional measurements of aperture size and for evaluating aperture corner radii and flange misalignment. Scattering parameters for the waveguide shim were calculated both from basic electromagnetic theory and by computer simulation. Surface roughness was also evaluated as it affects the transmission loss of a waveguide shim. In this paper we summarize the evaluation and calculation of waveguide shim standards, discuss the reproducibility in VNA measurements and consider extensions of the method to waveguide shims with smaller aperture sizes.

Performance of new design of waveguide flange for measurements at frequencies from 800 GHz to 1.05 THz

Waveguide flange design makes major impact to measurement reproducibility in the range of sub-millimeter-wave frequencies, e.g. 1.0 THz. The fundamental performance of new flange design at millimeter wave frequency, i.e. the frequency range from 220 GHz to 330 GHz, has been investigated and presented in 2011 [1]. Its flange alignment is ensured using alignment ring with tight tolerance, then, it is fully compatible to MIL-DTL-3922/67C (UG-387) flange. This paper describes an evaluation result of its capability of connection repeatability in the WM-250 (WR-1, 750 GHz-1100 GHz) frequency band. Furthermore, the quarter wave length shim, as a TRL “through” line standard, is specially modified to fit with a new design flange, then, its capability of connection repeatability is also evaluated and discussed.

Comparing accuracy of waveguide VNA measurement calibrated by TRL calibration using different length of line standard in terahertz band

We have evaluated the measurement uncertainty for rectangular waveguide Vector Network Analyzer (VNA) measurements in the WM-250 (WR 1.0), 750 GHz - 1.1 THz frequency band. We developed a new waveguide flange design for precise connections and dimensional measurements to establish traceability to SI in VNA measurements. TRL calibration method is useful for VNA calibration in the millimeter wave frequency region, but TRL line standards become thin, fragile and then increment of the risk of breakage of line standard at connection/reconnection cycle. This is the total investigation of measurement uncertainty for VNA measurement at Terahertz band comparing between both calibrations performed by single thin line and double thick lines as TRL line standards.

Standards Research in Japan: Latest Development of Millimeter-Wave and Submillimeter-Wave Measurements

In recent communication networks, 100 Gb/s passive optical Ethernet networks have been established and started becoming widely used. In consumer broadcasting, the use of high-definition television in studio and live-relay broadcasts has been planned by the Japanese government. These high-speed wireless technologies require the millimeter-wave frequency band from 30 to 300 GHz to provide sufficient bandwidth. In a wireless link system, spurious signals must be identified and managed in accordance with Japanese Radio Law relating to the recommendations by the International Telecommunication Union Radio section (ITUR). According to the regulations for spurious domain emission in ITU-R SM 329-10 (02/2003), limits on spurious domain emissions for radio equipment over the range of 9 kHz to 300 GHz must be currently considered and tested before being applied. The recommended frequency ranges of spurious domain measurement depend on the fundamental frequency in the wireless link system.

Consideration of error model with cable flexure influences on waveguide vector network analyzers at submillimeter-wave frequency

In microwave and millimeter wave frequency region, systematic error terms, i.e. directivity, matching and tracking, in vector network Analyzer (VNA) can be corrected by a calibration process. However, it is difficult to correct the other random error terms, i.e. connection repeatability and flexure influences of cables attached to test ports, etc. In the waveguide VNA using frequency extension modules, fortunately, it is unnecessary to consider cable flexure influences of test ports in the measurement uncertainty due to no test port cables being used. However, LO and RF cables making connection from frequency extension modules to microwave VNA have a large impact on the uncertainty in the transmission phase measurements. This paper proposes and demonstrates an evaluation technique of cable flexure influences of RF and LO cables in the millimeter and submillimeter wave VNA using frequency extension modules. Then, new VNA error model considering the LO and RF cable flexure influences are discussed.

Traceability to national standards for S-parameter measurements in waveguide at 1.1 THz

This paper describes a new measurement system to provide high precision traceable scattering parameter measurements of waveguide devices in the frequency range from 750 GHz to 1.1 THz (i.e. in waveguide size WR-01, WM-250). The measurement system comprises Vector Network Analyzer (VNA) at Yamaguchi University and associated primary reference standards provided by the National Metrology Institute of Japan (NMIJ). The standards are precise line sections of waveguide that are used in pre-calibration of the VNA. Traceability to the International System of units (SI) is achieved via precision dimensional measurements of the waveguide aperture and flange. Measurement results with uncertainties are given for traceable measurements in waveguides.

Evaluation of complex residual error in vector network analyzer measurement system in the range of millimeter-wave and submillimeter-wave frequencies

This paper describes a technique for the evaluation of complex residual errors in coaxial and waveguide vector network analyzer (VNA) measurements in the range of microwave, millimeter and submillimeter wave frequencies. The technique is based on reference values of scattering parameters for transmission line standards consisting of coaxial air dielectric lines and waveguide standard sections. Reference values traceable to SI-base units were calibrated for the standard transmission lines by the National Metrology Institute of Japan (NMIJ). Complex residual analyses are shown for VNA measurements with a PC-7 coaxial line system and with WR-15, WR-10 and WR-3 waveguide systems up to 330 GHz.

Measurement uncertainty in waveguide VNA calibrated by offset short calibration with oversized waveguide aperture at sub-millimeter wave frequency

This paper describes a new concept of calibration standards for waveguide Vector Network Analyzer (VNA) measurement in the millimeter and sub-millimeter wave frequency bands. High precision and traceable scattering parameter measurements have been established by using precision design of waveguide interface [1] and optimizing the measurement condition and setup of measurement system [2]. Even if using precision machining to make a precision waveguide, there is non-zero mechanical tolerance providing the degradation of connection repeatability. The National Metrology Institute of Japan (NMIJ) proposes to use the waveguide standard line with oversized aperture compared to aperture size of test-port waveguides. This new concept provides to improve the connection repeatability coming from misalignment. Results of the measurements and uncertainty estimation are described, and then, comparison results between conventional and new concepts are described for measurement uncertainty.

Establishment of S-parameter Traceability for 3.5 mm Coaxial Lines from 10 MHz to 100 MHz

This paper describes the National Metrology Institute of Japans (NMIJ) development of the International System of Units (SI) traceable S-parameter standard and measurement techniques in 3.5 mm coaxial lines at radio frequencies (from 10 to 100 MHz). The primary standard is a 300-mm-length air line. The S-parameters of the air line were evaluated by measuring the dimensions and the insertion loss. Using the offset load method, the reflection coefficient of a matched load termination was characterized to perform thru–reflect–match calibrations in vector network analyzer measurements. The uncertainty of the matched load termination, estimated by Monte Carlo simulations, was approximately 0.001 at 100 MHz.