Vector Network Analyzer Measurements Research Articles

Effects of natural zeolite and ferric oxide to electromagnetic and reflection loss properties of polyurethane nanocomposite

Microwave-absorptive polymeric composite materials are becoming important to protect interference of any communication systems due to increasing use of microwave-inducing devices. In this work, the microwave-absorptive polyurethane nanocomposites were prepared using natural zeolites of Sarulla North Sumatra and commercial ferric oxide as fillers. Weight ratios of the polyurethane to natural zeolite and ferric oxide were varied (90%:6%:4%; 80%:12%:8%; 70%:24%:6%) by weight. The fillers were prepared using ball milling technique and characterized for their particle size distributions using Particle Size Analyzer. The nanocomposites, prepared using in-situ reaction of polyethylene glycol, toluene diisocyanate and fillers. The complex permittivity (ε’and ε”) and complex permeability (μ’ and μ”) as electromagnetic properties were calculated using NRW method after collecting real and imaginary S parameter using Vector Network Analyzer measurement at X band frequency. Results show ratio of the fillers will affect the permeability, permittivity and reflection loss of the materials. The best reflection loss was shown -40.588 dB (>99 % absorption) at ratio for polyurethane : nanozeolite : ferric oxide (80%:12%:8%) by weight observed at 10.92 GHz. According to the measurement and calculation was shown the polyurethane filled with natural nanozeolite and ferric oxide is a good electromagnetic wave attenuation material.

Evaluation of a single-input multiple-output antenna array for ultra-wide band applications

Emerging applications for ultra-wide band (UWB) systems require high performance UWB array systems with excellent characteristics duly verified in time and frequency domains. Thus, we propose an UWB antipodal tapered slot antenna (ATSA) linear array operating over a 2–12GHz band, and present an experimental setup to validate the performance of the single-input, four-element output UWB antenna array system using time- and frequency-domain analysis based on vector network analyzer (VNA) measurements. The time-domain analysis of UWB antenna array is indispensable since each array element uses a wideband instead of a narrowband signal. We characterize the proposed array using an ultra-short pulse of 50ps. All measurements are done in an anechoic chamber to avoid multipath reflections. Our experimental work on time-domain analysis is a step towards realizing a practical timed array-based UWB test-bed for validating system performances in real conditions with practical impairments.

TEM-Like Launch Geometries and Simplified De-embedding for Accurate Through Silicon Via Characterization

Novel de-embedding launch geometries and a simplified analytical procedure are proposed to extract the exact electromagnetic behavior of a through silicon via (TSV) pair from measured data. First, the most recent de-embedding method is reviewed and it is deeply investigated using both 3-D simulation and vector network analyzer measurements to accurately evaluate its residual error. Then, some potential sources of error are hypothesized and overcome by the proposed launch geometries based on a de-embedding plane that is able to ensure a TEM (or quasi-TEM) mode propagation. The novel launches are studied through 3-D simulations; the previous de-embedding procedure is updated to consider the fringing effect of the open-end launch, and it is simplified reducing the launch standards from three to two. The proposed launch geometries and algorithm are shown to be more accurate in the TSV pair de-embedding with respect to the method currently employed.

A W-Band TE12-Mode Input Converter With Nonuniform Bragg Cavities

A method to launch a circular TE12 mode as the input converter of a W-band high-order mode gyrotron travelling wave tube was proposed and verified by the simulation and cold test. The TE12 mode is stimulated by a broadband Y-type power divider. Instead of the cutoff waveguide, a nonperiodic Bragg reflector was adopted to overcome the issues of smaller beam tunnel dimensions and higher electron interception. Simulation design reveals that two different kinds of Bragg reflectors can achieve the performance we need. Identical converters with and without the corrugated reflectors for the back-to-back millimeter wave measurements were manufactured using the computerized numerical control technique. Vector network analyzer measurements of the converter transmission, reflection, and isolation are all in good agreement with our simulated results.

Enhancement of microwave absorption properties on modified kapton film by ion implantation process

Kapton-polyimide films have been modified by using ion implantation of Fe and Gd ions at dose 1 × 1017 ions/cm2 and energy ions 30 keV. From X-ray diffractions (XRD) were verified the existence phases such as iron oxide, or Gd-oxide and graphitic carbon. Vibrating sample magnetometer (VSM) measurement the films showed a paramagnetic behavior. Microwave absorption (MWA) properties were measured by vector network analyzer (VNA) at X band range (8-12GHz). VNA measurement results showed the enhancement of MWA from -22dB for Kapton original film to -35dB for S11 vector direction and until -40 dB for S22 vector direction of modified Kapton film by Fe and Gd ions. It can be concluded that the nanostructure of embedded Fe-oxide or Gd-oxide nanoparticles on the near surface of Kapton film take a role and gives a rise the MWA properties of film.

Vector network analyzer measurement of the amplitude of an electrically excited surface acoustic wave and validation by X-ray diffraction

Surface acoustic waves are used in magnetism to initiate magnetization switching, in microfluidics to control fluids and particles in lab-on-a-chip devices, and in quantum systems like two-dimensional electron gases, quantum dots, photonic cavities, and single carrier transport systems. For all these applications, an easy tool is highly needed to measure precisely the acoustic wave amplitude in order to understand the underlying physics and/or to optimize the device used to generate the acoustic waves. We present here a method to determine experimentally the amplitude of surface acoustic waves propagating on Gallium Arsenide generated by an interdigitated transducer. It relies on Vector Network Analyzer measurements of S parameters and modeling using the Coupling-Of-Modes theory. The displacements obtained are in excellent agreement with those measured by a very different method based on X-ray diffraction measurements.

Co/graphite based light weight microwave absorber for electromagnetic shielding and stealth applications

The magnetic, thermal, thermo-mechanical, electromagnetic and microwave absorption properties of Co/graphite loaded polystyrene composites prepared by melt blending and injection molding techniques are studied in X-band (8.4–12.4 GHz) for seeking their usage as efficient light weight microwave absorbers. For profound understanding of electromagnetic absorption process at micro level, the advanced SEM and x-ray diffraction testing of the composites are carried out. The magnetic properties of the prepared Co/graphite loaded polystyrene composites are studied using the vibrating sample magnetometer. The thermal stability and thermo-mechanical properties of the prepared composites are analyzed by thermo gravimetric analysis and dynamic mechanical and thermal analysis, respectively. The complex permittivity and permeability values of the prepared composite samples in X-band of microwave frequency are extracted from the scattering data recorded during the vector network analyzer measurements. The minimum reflection loss (maximum absorption loss) of −32.02 dB (99.94%) is achieved at 10.13 GHz for Co/graphite loaded polystyrene composite with the excess loading of graphite flakes for sample thickness of 1.8 mm. High absorption loss, light weight and low thickness of the proposed multicomponent Co/graphite loaded polystyrene composites make them promising candidates for electromagnetic shielding and stealth applications.

Direct transduction method for measuring the ultrasonic attenuation in Si(111) in the frequency range 100 MHz–1 GHz

Abstract A direct ultrasonic transduction method was investigated as a function of frequency in order to evaluate the ultrasonic attenuation in doped n-type Si(111) by using a setup where an incorporated small spring acts as an adjustable coil. Measurements were performed in the frequency range from 100 MHz to 1 GHz using an AlN transducer produced directly on the Si sample. A vector network analyzer (VNA) was used to record the acoustic reflections. Dependence of the generated wave central frequency on transducer thickness, active area and circuit impedance was examined. One-dimensional (1D) simulations using an equivalent electrical circuit were carried out to validate the VNA measurements. An overall agreement was observed. The wave attenuation in the highly doped n-type Si(111) was found to have a quadratic dependance on the frequency.

Design and Microwave Measurement of a Novel Compact TE $_{0n}$ /TE $_{1n'}$ -Mode Converter

A novel method to generate a TE $_{0n}^{{{(\mathrm {C})}}}$ ( $n = 1$ , 2, 3) ( $C$ is circular for short) or TE $_{1n'}^{{{(\mathrm {C})}}}$ ( $n' = 2$ , 3, 4) mode via a TE $_{m0}^{{{(\mathrm {R})}}}$ ( $m = 2n$ or $m = 2n' - 1$ ) ( $R$ is rectangular for short) mode generator is proposed in this paper. Two main components, including a TE $_{10}^{{{(\mathrm {R})}}}$ –TE $_{m0}^{{{(\mathrm {R})}}}$ mode converter with multiple coupling apertures and matching steps and a TE $_{m0}^{{{(\mathrm {R})}}}$ –TE $_{0n}^{{{(\mathrm {C})}}}$ or TE $_{1n'}^{{{(\mathrm {C})}}}$ mode converter, were, respectively, demonstrated. Two novel compact mode converters, respectively, exciting the TE $_{01}^{{{(\mathrm {C})}}}$ and TE $_{13}^{{{(\mathrm {C})}}}$ modes at $Q$ - and $W$ -band based on the aforementioned methodology were designed and analyzed. In the TE $_{01}^{{{(\mathrm {C})}}}$ mode converter design, symmetric cylindrical ridges were introduced to improve the mode purity and suppress the unwanted TE $_{21}^{{{(\mathrm {C})}}}$ mode by cutting off its surface current on the metal wall. Such a mode converter operating at $Q$ -band was manufactured and vector network analyzer measurements showed excellent S-parameter performance (port reflection 90%), which agreed very well with our simulation. Besides, as an expansion of the TE $_{01}^{{{(\mathrm {C})}}}$ mode converter, the designed results of a high-order TE $_{13}^{{{(\mathrm {C})}}}$ mode converter excited by a similar methodology were also presented.

Structure, crystallization and dielectric resonances in 2–13 GHz of waste-derived glass-ceramic

Structure, kinetics of crystallization, and dielectric resonances of waste-derived glass-ceramic prepared via quench-heating route were studied as a function of dosage of iron ore tailing (IOT) within 20–40 wt% using X-ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), and vector network analyzer (VNA) measurements. The glass-ceramic mainly consisted of ferrite crystals embedded in borosilicate glass matrix. Crystallization kinetics and morphologies of ferrite crystals as well as coordination transformation of boron between [BO4] and [BO3] in glass network were adjustable by changing the amount of IOT. Dielectric resonances in 6–13 GHz were found to be dominated by oscillations of Ca2+ cations in glass network with [SiO4] units on their neighboring sites. Ni2+ ions made a small contribution to those resonances. Diopside formed when IOT exceeded 35 wt%, which led to weakening of the resonances.

Wideband Circular TE21and TE01Mode Converters With Same Exciting Topologies

To accurately measure the performance of dielectric loaded circuits for gyrotron traveling wave tubes, a novel topological structure to generate the TE21○ or TE01○ (superscript represents circular waveguide) mode is proposed and verified in this paper. The topology is constituted by an overmoded TE10□ to TE20□ (superscript represents rectangular waveguide) mode converter with multiple matching steps and a taper from TE20□ to TE21○ or TE01○ mode. This topology allows the TE21○ or TE01○ mode to be excited by changing the taper dimensions. Simulation results reveal that the TE21○ and TE01○ mode converters, respectively, have a 1-dB bandwidth of 12.8 and 9.3 GHz with an excellent performance. Converters for the back-to-back millimeter-wave measurements were fabricated with computerized numerical control and wire cutting techniques. Vector network analyzer measurements are in good agreement with the simulations.

General Method for Characterization of Power-Line EMI/RFI Filters Based on S-Parameter Evaluation

This paper deals with a general working approach for determining the lowest possible insertion loss of power-line interference filters in their stop bands at high megahertz or gigahertz frequencies. It is shown that at these frequencies, the measurement methods recommended for testing of interference filters in available standards for frequencies up to 1 GHz fail in determining their lowest possible insertion loss. This problem is solved by the newly developed method which also enables the characterization of concerned filters in a completely impedance unknown environment. It is based on two-port vector network analyzer measurement and postmeasurement data processing applying an impedance matching technique. Experimental verification of the new method using two Maury Microwave automated tuners and a cascade of low-pass coaxial filters was performed in the frequency band from 6 to 12 GHz. The results show that measurement-evaluation procedures performed according to the newly developed method provide more reliable and precise results when compared to measurement procedures corresponding to methods described in common standards. The new method was also applied to the characterization of a professional EMI/RFI filter from 1 to 10 GHz.

Practical approach to power integrity‐driven design process for power‐delivery networks

The authors present a practical design process that considers the power noise problem in CPU blocks for application processors used in smart TVs. The target impedance is determined by modelling the RLC circuit of a system-on-chip power net. The target impedance of a power delivery network is then determined by applying the extracted chip current profile for finalising the design budget. The authors modelled the on-chip power net by combining vector network analyser measurements with an on-chip model for power integrity analysis. The authors demonstrated the optimisation and design strategy by using a ball grid array ball interconnection and case studies on the placement of multilayer ceramic capacitors. The simulation results showed good agreement with the measurement results. The error in the minimum value (negative direction) by voltage droop was less than 8.6%, while the difference in voltage noise ripple was 2.69% for a criterion of 1.1 V assuming a worst-case condition of 1.2 V.

Revisiting the Effect of Nickel Characteristics on High-Speed Interconnect Performance

It has been observed that some surface finish like nickel–gold plating has exhibited significantly higher losses than expected on high-speed interconnects like printed circuit board (PCB) trace and packaging. The investigation has revealed that this extra loss results from the ferromagnetic characteristics of nickel material with large resistivity and nonunit frequency-dependent relative permeability. As a result, a high-speed PCB design must take into account the board surface finish effect, solder-mask coating, and the physical geometry deformation of copper related to the etching process when modeling the PCB trace, which can be accomplished by using 3-D electromagnetic field simulation tools. Simulation results are correlated with vector network analyzer (VNA) measurements on several test cases and also on the actual application boards. In our experimental studies on PCB test structures with electroless nickel/immersion-gold (ENIG) and electroplated nickel–gold plating, there is no observation of resonating anomalies in the insertion loss and group delay related to nickel permeability. Both simulation and measurement results have demonstrated that PCB board with ENIG and solder mask over bare copper finish has less signal loss than that with ENIG or hard-gold finish.

Crosstalk and Mode Conversion in Adjacent Differential Lines

In this paper, the concepts of weak coupling and weak imbalance are exploited to investigate crosstalk and mode conversion occurring in perfectly balanced differential lines (DLs) due to proximity with other DLs printed on the same PCB substrate. Approximate modal circuits are derived, where the aforementioned phenomena are accounted for by the use of distributed voltage and current sources. This allows evidencing the relevant parameters at the basis of these undesired phenomena, which may significantly degrade DL performance in terms of emission and immunity properties as well as signal integrity. Accuracy of the proposed model, preliminary validated versus exact solution of transmission line equations, is eventually assessed through vector network analyzer measurements carried out on a PCB sample.

Design and Microwave Measurement of a Broadband Compact Power Coupler for Sheet Beam Traveling Wave Tubes

Novel compact input and output couplers for broadband operation of sheet beam traveling wave tubes are analyzed, designed, and cold tested. Multistage stepped waveguide and cascaded Bragg resonators are proposed and applied to improve the performance and extend the operating bandwidth. Optimized curve-Bragg resonators are studied to correct the phase between the reflector and $H$ -bend waveguide, which bring about a further enhancement of the coupler behavior. HFSS simulations predict a −3 dB transmission bandwidth about 38% and 34% are achieved, respectively, in Ku and $Q$ band. Besides, the large beam tunnel property of this kind of coupler benefit the beam transport of sheet beam devices. Different components as the input and output couplers for Ku- and $Q$ -band SB-TWT are manufactured and cold tested. Results of vector network analyzer measurement and simulation present an excellent agreement.

Modeling of SOL calibration standards for PCB channel probing

On-wafer probes are used to obtain vector network analyzer (VNA) measurements for the close packed PCB channels in the system applications. The S-parameter model of the probes is de-embedded from channel data in a two-tier calibration, which is an efficient option to perform the calibration. The one port method with short-open-load (SOL) standards derives the probe models. Its accuracy relies on the accurate knowledge of the electrical property of the SOL standards used in the calibration. In this paper, the modeling methodology of SOL standards on the calibration substrate is presented. The models for SOL standards are determined empirically by using the measured zero-length thru data as a reference. An optimization algorithm is applied to aid the search of the best models for SOL standards. The standards are also simulated with a 3D full wave field solver to capture the physical aspect of the layout of the standards directly, though it is limited as an approximation.

Sub-fF 130 nm MOS Varactor Characterization Using 6.8 GHz Interferometry-Based Reflectometer

Nanometer-scaled communication devices for microwave and millimeter wave applications motivated innovative techniques in modeling and characterization. In this letter, an interferometry-based reflectometer (IBR), comprising Vector Network Analyser (VNA) and commercial devices, is implemented. Using sub-fF 130 nm thick-oxide accumulation MOS varactors from ST Microelectronics, IBR and VNA measurements are compared to a silicon-based model. A capacitance from 0.9 to 1.6 fF around 6.8 GHz is estimated. IBR demonstrates a root-mean-squared (RMS) error related to silicon-based model of 60 aF, while VNA has 70 aF in its best case. The mean accuracy is estimated at 40 aF and 11 aF respectively for VNA best case and IBR in C-V measurements. This letter demonstrates that IBR solution has smaller RMS error and better accuracy for C-V measurements than VNA.

The Influence of Sintering Temperature and Mn-Ti Doped BaFe<sub>12</sub>O<sub>19</sub> on the Microwave Absorbing Properties

The effect of sintering temperature and Mn-Ti (x = 0.1 and 0.5 % mol) doped in Barium hexaferrite (BaFe12O19) on the microwave absorption properties have been investigated. The BaFe(12-2x)MnxTixO19samples were prepared by using a solid state reaction method from technical grade materials of BaCO3, Fe2O3, MnO2, and TiO2. The permagraph and vector network analyzer (VNA) measurement with frequency of 4 – 10 GHz were used to determine the magnetic properties and microwave absorbing properties, respectively. The magnetic induction and magnetizing force (B-H) curve analysis of BaFe(12-2x)MnxTixO19revealed that by increasing the Mn-Ti dopant concentrations, the remanence (Br) and BH(max) increases, meanwhile, the HCBvalue decreases for both 1100 and 1150oC. The frequency dependence of reflection loss (RL) measurement given anoptimum value of-26.15 dB at frequency of 9.18 GHz which obtained by x = 0.1% mol Mn-Ti (1100oC). The maximum absorption peak was achieved for 0.5 % mol Mn-Ti sample with ~98.3 % at 9.18 GHz. By controlling the sintering temperature and Mn-Ti dopant concentration, the RL and absorption behavior can be modified to desirable values and also indicates that higher Mn-Ti dopant concentration (0.5% mol) possess better absorbing characteristics. Furthermore, it was found that complex permitivitty and permeability values of BaFe12O19can be modified by controlling the Mn-Ti dopant concentration.

Accuracy and Bandwidth Optimization of the Over-Determined Offset-Short Reflectometer Calibration

We present a new method for calculating line lengths of offset-short standards so as to provide a broadband and accurate one-port vector-network-analyzer (VNA) calibration. Our method is based on an approximate uncertainty analysis of corrected VNA measurements. We estimate the maximum value of the total variance (i.e., the trace of the covariance matrix) of errors in those measurements at a single frequency, and then quantify the quality of the offset-short calibration in a given frequency range with two metrics: the upper bound for the total variance and the lower calibration frequency. We then apply a global bi-objective optimization to these metrics in order to determine the optimal lengths. In order to verify our approach we first validate assumptions made in the approximate uncertainty analysis through a Monte Carlo simulation. We further perform an experiment in which we compare measurements of verification devices after calibrating the VNA with different offset-short sets designed with our method and with a set of reference airlines. Finally, we perform an uncertainty analysis for these measurements, which demonstrates the tradeoff between the offset-short calibration bandwidth and accuracy, and shows that our approach for selecting the offset-short line lengths provides the broadest bandwidth for a given calibration accuracy.