One-port Measurements Research Articles

Broadband complex permittivity determination using a two-port U-shaped coplanar waveguide with artificial neutral network algorithm

A two-port U-shaped Coplanar Waveguide (U-CPW) used for broadband complex permittivity measurement of high loss solutions is presented. Compared with the one-port measurement device, this two-port U-CPW coupled with artificial neural networks algorithm has the ability of reducing the multiple-solutions. Also, the measured T/R (transmission/reflection) coefficients were used instead of simulated reflection coefficients for training the neural networks that enhanced the accuracy of measurement results. Two real-valued neural networks associated with the U-CPW are used to reconstruct the two parts of the complex permittivity separately from the measured T/R coefficients. First, a large number of measured T/R coefficients of broadband frequency points of ethanol-water mixtures along with their theoretical complex permittivity are used to train two separate neural networks. Second, the trained networks are employed to reconstruct the complex permittivity of other solutions using the measured T/R coefficients. Compared with the results of Cole-Cole equation, the reconstructed results of methanol-water mixtures and ethanol-methanol mixtures at different volume fractions have been obtained with sufficient degree of accuracy in the frequency range 1–3 GHz at 20°C. For predicted values using the developed artificial neural network (ANN) architecture and those obtained from literature, the average relative errors of real and imaginary parts of complex permittivity are 2.27% and 2.12%, respectively.

Indirect Contact Probing Method for Characterizing Vertical Interconnections in Electronic Packaging

This letter proposes a new indirect contact probing method to characterize vertical interconnections without contact damage. At the first step of the proposed technique, multiple one-port calibration measurements should be performed to characterize the contactor layer between the probe pads and the device-under-tests (DUTs). The characteristics of the actual vias as the DUTs are then extracted from indirect-contact measurements by de-embedding the contactor layer. In simulations and experiments at frequencies range from 2.5 to 18 GHz, we have verified via defects can be successfully identified from the indirect-contact measurements.

Two-step numerical procedure for complex permittivity retrieval of dielectric materials from reflection measurements

A two-step measurement procedure has been proposed for measurement of complex permittivity of dielectric materials using one-port reflection measurements. In the procedure, as a first step, a graphical method is applied to analyze on the complex reflection-coefficient plane the general pattern of dielectric behavior of the sample. Then, as a second step, optimization algorithms are utilized for retrieving electrical properties of samples. The procedure requires measurement of complex reflection scattering parameters of at least two samples with different lengths. It has been validated by X-band measurements of three polyvinyl chloride samples with lengths 5, 10, and 20 mm.

The Use of a Vector Circuit Analyzer to Measure the Parameters of Microwave pin-Diodes

A method for directly measuring the loss resistance for microwave pin-diodes using a vector circuit analyzer is considered. The problems involved in constructing a contact device for the pin-diodes and for calibration are analyzed. An installation circuit for one-port and two-port measurements is presented.

Repeatability and Mismatch of Waveguide Flanges in the 500–750 GHz Band

This paper presents a study characterizing the connection repeatability and reflection coefficient of submillimeter waveguide flanges in the 500-750 GHz band (WR-1.5 or WM-380). The connection repeatability of four types of flange was measured using one-port measurements and a “load-reference” technique with a vertically mounted system to mitigate gravitational bias. To measure the error-corrected complex reflection coefficients of pairs of waveguide flanges, a calibration procedure insensitive to flange misalignment was used. This SDD(RO) calibration method employs four standards: a flush short, two delay shorts with different but unspecified offsets, and a radiating open-ended waveguide. The uncertainty associated with this calibration method is investigated and it is used to estimate the reflection coefficient resulting from flange misalignment.

The IF Output Impedance of SIS Mixers

In this paper, we describe a measurement setup to characterize the intermediate frequency (IF) impedance of cryogenically cooled superconductor-insulator-superconductor (SIS) mixers. A setup based on a commercial vector network analyzer (VNA), a circulator and a low noise amplifier (LNA) has allowed to increase the dynamic of the VNA and to perform accurate one-port measurements across a high dynamic range of the SIS mixers IF band. The mixers were biased in three different regions of their unpumped IV curve to obtain three known impedances which are close to the classical calibration SOLT standards (Short, Open, Load, Thru): the reference plane was located at the SIS junction itself and the calibration procedure allowed to calibrate out all IF circuitry of the measurement setup, including the on-chip SIS mixer intrinsic capacitance and inductance without requiring to thermally cycle and open the cryostat to locate and measure the different calibration standards. Thus, the devised method provides a simple and direct measurement of the SIS mixers IF impedance which can be used for quick, accurate and highly repeatable IF characterization of any type of millimeter and sub-millimeter wave SIS mixers. The measurement method is described and the experimental results of the IF output impedances of 3 mm band DSB and SSB mixers with 4 GHz wide IFs (across 4-8 GHz) are presented and compared with simulated predictions obtained from combining Tucker's SIS mixer theory and accurate electromagnetic modeling of the mixer structure.

A new method to measure permittivity and permeability in nanopowder materials in microwave range

A new method for measuring the electromagnetic properties (permittivity and permeability) of nanopowder materials in a wide microwave region is presented. Unlike previously developed systems, our experimental setup is based on reflection measurements over a short-circuited transmission line combined with the application of a uniform magnetostatic field. When this field is sufficiently high to saturate the material, the effective permeability of the sample equals the permeability of free space, without modifying its electrical properties. Hence, for each frequency, the permittivity can be obtained through the measurement of a single scattering parameter, such as the reflection coefficient. After this first measurement, and once the external field is removed, the reflection coefficient can be used again to obtain the permeability by means of the permittivity value obtained before. As the major advantage, this procedure allows the recording of the experimental data in just one sweep, using one-port measurements, and without modifying the geometrical characteristics of the sample holder. Hence, the measurement process can be easily automated.

Experimental and numerical determination of the correlation function of level velocities for microwave networks simulating quantum graphs

The parameter-dependent correlation function of level velocities is studied experimentally and numerically. The measurements were made for microwave networks simulating quantum graphs. One- and two-port measurements of the scattering matrix necessary for determining the correlation function were realized for the five vertices networks. For the fully connected six vertices network, one-port measurements were made. The obtained experimental and numerical results are compared with the predictions of random matrix theory.

Estimation of Complex and Linear Uncertainities in S-Parameter Measurements for Metrology Applications

The present paper aims to develop a uniform procedure of estimating uncertainty components in VNA measurements whether in complex or linear units. The individual response of each uncertainty components have been studied in the frequency range 1 to 18 GHz, which are applicable for one-port and two-port measurements. The Vector network analyser (VNA) measurements are performed to assign an overall uncertainty for the respective measuring parameter in terms of comp lex and linear units for coaxial step attenuator, fixed attenuator and mis match. These measurements are then verified through the primary and transfer standards of the attenuation and impedance parameters and thus the traceability of the VNA measurements is established. Finally, the outcome of co mplete study has been presented as VNA measurements based new calibrat ion and measurement capabilit ies (CM Cs) for NPL, India. It has shown that the final combined uncertainty is found same or nearby by obtaining from uncertainty components either in complex or in linear units. Thus, this paper reports the estimation of VNA measurement uncertainties for various parameters as per the requirements of IS O/IEC 17025:2005 standard.

High-$Q$ Integrated CMOS-MEMS Resonators With Deep-Submicrometer Gaps and Quasi-Linear Frequency Tuning

Integrated CMOS-MEMS free-free beam resonators using pull-in mechanism to enable deep-submicrometer electrode- to-resonator gap spacing without interference in their mechanical boundary conditions (BCs) have been demonstrated simultaneously with low motional impedance and high Q. The key to attaining high Q relies on a decoupling design between pull-in frames for gap reduction and mechanical BCs of resonators. In addition, the use of metal-SiO2 composite structures has been proved to greatly benefit the thermal stability of CMOS-MEMS resonators. Furthermore, tuning electrodes underneath pull-in frames were designed to offer “quasi-linear” frequency tuning capability where linear relationship between tuning voltage and frequency was achieved. In this paper, CMOS-MEMS free-free beam resonators with gap spacings of 110, 210, and 275 nm, respectively, were tested under direct one-port measurement in vacuum, demonstrating a resonator Q greater than 2000 and a motional impedance as low as 112 kΩ and, at the same time, allowing quasi-linear frequency tuning to achieve a total tuning range of 5000 ppm and a sensitivity of 83.3 ppm/V at 11.5 MHz with zero dc power consumption. Such a resonator monolithically integrated with a CMOS amplifier, totally occupying a die area of only 300 μm × 130 μm, was also tested with enhanced performance, benefiting future timing reference and RF synthesizing applications.

Importance and estimation of mismatch uncertainty for RF parameters in calibration laboratories

A number of calibration techniques are used in Radio Frequency (RF) calibration for power, attenuation and impedance parameters. Mismatch uncertainty plays a major role in these measurements and in estimation of combined uncertainty according to ISO/IEC 17025:2005 and GUM document. Formulas to evaluate the mismatch uncertainty in terms of reflection coefficient, voltage standing wave ratio and scattering parameters have been evaluated earlier and are being used in RF calibration. The present paper summarizes the mismatch formulas previously studied and the modified ones suitable to the measurement system and techniques available today. For power and attenuation calibration in the particular frequency range, an establishment of traceability for one-port measurement in the same frequency range is required. The methods to reduce and control this uncertainty component and their limitations are also discussed forbest measurements practices in the calibration laboratories.

Investigation of Loading Effect on Power Performance for Planar Gunn Diodes Using Load-Pull Measurement Technique

A one-port load-pull measurement has been carried out in order to investigate the effect of loading on the RF power performance of a planar Gunn diode operating in the transit-time mode at 102 GHz. A W-band manual E-H tuner was applied between a waveguide mixer and a wafer probe to vary the load impedance on the Gunn diode. It has been found that more than 25 dB variation of output power was obtained by systematically adjusting the tuner. By de-embedding the S-parameters of the probe, E-H tuner and mixer, the relationship between RF power and load impedance for the planar Gunn diode was derived. This method is extremely useful for assisting the design of matching networks to improve power output of one-port oscillator devices.

A New Indirect Calibration Method for an Equivalent Source Mismatch of a Power Splitter Using Measurements at Only One Port

A new measurement procedure is described for determining the equivalent source mismatch Γ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">G</sub> of a power splitter. It uses a vector network analyzer (VNA) configured for one-port calibration and measurement. The power splitter ports that are not connected to the VNA test port are loaded in turn with characterized standards, such as an open, a short, a load, and a termination. It also takes advantage of the reciprocity characteristic of the power splitter. As the system impedance is normalized to the impedance of the termination, the termination works as a perfect load in measurements and calculations for the S-parameters of the power splitter. Γ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">G</sub> is calculated from the renormalized S-parameters to <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Z</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> . The propagation of uncertainties is analyzed.

First-Order Elastic Nonlinearities of Bulk Acoustic Wave Resonators

We propose a procedure to characterize the intrinsic nonlinearities of bulk acoustic wave resonators by performing one-port measurements of the second harmonic and second-order intermodulation spurious signals. Closed-form expressions have been derived that relate the nonlinear stiffened elasticity with experimental observables. These formulas are valid in a wide range of frequencies around the resonance and have been verified with nonlinear circuit simulations. The measurement setup and its effects are also discussed in our approach. Measurements of a set of aluminum nitride-based devices from several manufacturers yield consistent model parameters and allow us to obtain a coefficient of the nonlinear stiffened elasticity intrinsic to this piezoelectric material.

Compact Gaussian Beam System for S-Parameter Characterization of Planar Structures at Millimeter-Wave Frequencies

This paper describes the design and implementation of a compact quasi-optical Gaussian beam system for measuring the frequency response of millimeter-wave materials, frequency-selective surfaces, and antenna elements in the array environment. The core components of this system are two wideband millimeter-wave focusing array antennas that act as adapters between the coaxial ports of the network analyzer and the wave ports defined at the input and output planes of the device under test. The use of planar focusing arrays for generating the Gaussian beams leads to very compact measurement setups with a total length of only a few centimeters. This paper addresses the design of the Ka/Q-band focusing arrays and demonstrates the utility of the proposed system through experiment. A useful method that allows reproducing two-port S-parameters from one-port measurements will also be introduced.

Detection and Localization of Load Coils from One-Port Measurements

This paper deals with detection and localization of load coils in the copper access network. The load coil is a legacy device that must be removed before deploying broadband services on twisted-pair transmission lines. The proposed methods do not require dedicated hardware but utilize the already installed transceivers for one-port measurements of the line input impedance. The number of load coils is detected by counting the number of resonance peaks in the line impedance spectrum. An approximative model of the symmetric loaded line is presented, from which a low-complexity load coil locator is derived. For nonsymmetric lines, a load coil locator using model-based optimization is proposed. The two methods are compared and evaluated by computer simulations and by laboratory measurements on real transmission lines. The estimation results indicate that up to five load coils can be robustly detected and located with the proposed methods.

Line Topology Identification Using Multiobjective Evolutionary Computation

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> The broadband capacity of the twisted-pair lines strongly varies within the copper access network. It is therefore important to assess the ability of a digital subscriber line (DSL) to support the DSL services prior to deployment. This task is handled by the line qualification procedures, where the identification of the <emphasis emphasistype="boldital">line topology</emphasis> is an important part. This paper presents a new method, denoted topology identification via model-based evolutionary computation (TIMEC), for line topology identification, where either one-port measurements or both one- and two-port measurements are utilized. The measurements are input to a model-based multiobjective criterion that is minimized by a genetic algorithm to provide an estimate of the line topology. The inherent flexibility of TIMEC enables the incorporation of a priori information, e.g., the total line length. The performance of TIMEC is evaluated by computer simulations with varying degrees of information. Comparison with a state-of-art method indicates that TIMEC achieves better results for all the tested lines when only one-port measurements are used. The results are improved when employing both one- and two-port measurements. If a rough estimate of the total length is also used, near-perfect estimation is obtained for all the tested lines. </para>

Filter characterisation using one-port pulsed radio-frequency measurements

A method for extracting the loaded quality factor of the first resonator of a bandpass filter using one-port measurements is introduced. Properties of the quality factor are reviewed, and a time-domain approximation is used to estimate the loaded Q value from the decay rate of the filter's natural response. Narrowband 900 MHz Chebyshev filters are characterised.

Micromachined thin film plate acoustic wave resonators (FPAR): Part II

Improved performance thin-film plate acoustic wave resonators (FPAR) using the lowest order symmetric Lamb wave (S0) propagating in highly textured AlN membranes have been previously demonstrated for the first time. In this work, an experimental study of the resonators' performance vs. a variety of design parameters is performed. Devices operating in the vicinity of the stopband center exhibiting a Q-value of up to 3000 at a frequency of around 875 MHz are demonstrated. Further, low-loss high-Q micromachined 2-port longitudinally coupled thin-film resonators using the S0 mode are demonstrated for the first time. For the analysis of the proposed structures, the coupling-of-modes (COM) approach is successfully employed. Initially, the COM model is used for the extraction of physical parameters from one-port FPAR measurements. Subsequently, using the COM model, a satisfactory agreement with the proposed experimental frequency characteristics of S0 2-port FPARs has been achieved, and possibilities for further improvements in the performance discussed. Finally, the frequency spectrum of the one-port devices has been studied and the excited plate modes at different frequencies identified and presented with their Q-factors and temperature coefficients of frequency (TCF).

Split Frequencies and Susceptances of the Three-Port Junction Circulator From an Experimental Determination of the Complex Gyrator Circuit

The adjustment of the classic three-port circulator involves an in-phase eigen-network and a pair of split counter-rotating ones. The purpose of this paper is to use some recent relationships to experimentally extract the split susceptances of the counter-rotating immittances and the susceptance slope parameter of the junction by having recourse to a one-port measurement of its complex gyrator circuit. This is done under the assumption that the in-phase eigen-network of the junction may be idealized by an electric wall. The split frequencies of the counter-rotating eigen-networks of the circulator may also be deduced from this characterization and are in good agreement, under the same assumption, with those derived from one-port measurements on a terminated circulator. The latter arrangement does not, however, allow the split susceptances of the counter-rotating eigen-networks to be deduced.