Synthetic TDR Measurements for TEM and GTEM Cell Characterization

This paper describes the main features of the timedomain reflectometry (TDR) measurement technique and, in particular, the TDR analysis performed using a proper operating mode of the vector network analyzer (VNA), which is called synthetic TDR. Furthermore, some results of reflection measurement, which aim to characterize the impedance behavior of transverse electromagnetic (TEM) and gigahertz TEM cells by means of a commercial VNA in time-domain mode, are presented

Accuracy Improvement of Real-Time Load-Pull Measurements

This paper describes a new procedure aimed to improve the effectiveness of real-time load-pull calibration. Loadpull measurement accuracy is strongly affected by calibration residual uncertainty. The novel methodology reduces this uncertainty contribution by means of error terms optimization. The proposed method has been tested with simulations and applied to actual measurement data. Considerable improvements have been achieve

New data on OZI rule violation in bar{p}p annihilation at rest

The results of a measurement of the ratio R = Y(phi pi+ pi-) / Y(omega pi+ pi-) for antiproton annihilation at rest in a gaseous and in a liquid hydrogen target are presented. It was found that the value of this ratio increases with the decreasing of the dipion mass, which demonstrates the difference in the phi and omega production mechanisms. An indication on the momentum transfer dependence of the apparent OZI rule violation for phi production from the 3S1 initial state was found.Comment: 11 pages, 3 PostScript figures, submitted to Physics Letter

Experimental antiproton nuclear stopping power in H2 and D2

Data about antiprotons slowing down in gaseous targets at very low energies (E<1 keV) show that the stopping power in D2 is lower than in H2; the right way to explain this behavior seems to be through a nuclear stopping power derived from the classical Rutherford formula

Trends of Traceability and Accuracy Assessment in Vector Network Analyzer

Modern Vector Network Analyzers are powerful vector measurement systems for high frequency device characterization, in terms of scattering parameters. These instruments need a complex calibration procedure, aimed to remove the greater part of the errors associated to the hardware and to trace measurements to primary standards. Actually, these primary standards are only indirectly associated to SI fundamental electrical quantities. The more suitable standards are sections of transmission lines, characterized by means of dimensional measurements. The system accuracy is mainly related to the uncertainty of the standards , which propagates to the calibration coefficients of the network analyzer, according to the algorithms used by the calibration process. Systematic errors not removed by the calibration process, define a scattering matrix that must be anyway evaluated, for the final measurement uncertainty. Network Analyzer accuracy assessment after calibration process is widely described in the literature, but some clarifications are necessary, in order to avoid not consistent interpretations. For the same reasons, the measurand analysis would need a revision. Indeed, also in high-level comparisons, discrepancies arise among participants using instrumentation of equivalent performances, a result clearly due to different interpretation of the analysis rules. The authors suggest simple principles, in order to improve the harmonization of the measurement results

Trends of traceability and accuracy assessment in Vector Network Analyzers

Modern Vector Network Analyzers are powerful vector measurement systems for high frequency device characterization, in terms of scattering parameters. These instruments need a complex calibration procedure, aimed to remove the greater part of the errors associated to the hardware and to trace measurements to primary standards. Actually, these primary standards are only indirectly associated to SI fundamental electrical quantities. The more suitable standards are sections of transmission lines, characterized by means of dimensional measurements. The system accuracy is mainly related to the uncertainty of the standards , which propagates to the calibration coefficients of the network analyzer, according to the algorithms used by the calibration process. Systematic errors not removed by the calibration process, define a scattering matrix that must be anyway evaluated, for the final measurement uncertainty. Network Analyzer accuracy assessment after calibration process is widely described in the literature, but some clarifications are necessary, in order to avoid not consistent interpretations. For the same reasons, the measurand analysis would need a revision. Indeed, also in high-level comparisons, discrepancies arise among participants using instrumentation of equivalent performances, a result clearly due to different interpretation of the analysis rules. The authors suggest simple principles, in order to improve the harmonization of the measurement results

A Simple Calibration Alghorithm for Partially Leaky Model Multiport Vector Network Analyzers

Calibration of leaky multiport vector network analyzers can be a long and time consuming procedure, unless calibration model and number of standard connections are somehow optimized. In this paper we present an optimized solution for a practical set of multiport problems, where calibration model can be divided in two separate leaky halves, neglecting leakage between them. This problem is typical for multiport on-wafer measurements, where multi-signal probes (e.g. GSGSG) are implied. We show that with a proper choice of calibration standards, the optimized calibration procedure takes the same time of a classical two port LRM or TR