Microwave Connectors Research Articles

Domain Decomposition Hybrid Implicit–Explicit Algorithm with Higher-Order Perfectly Matched Layer Formulation for Electrical Performance Evaluation under Low-Pressure Discharge Phenomenon

Low-pressure discharge events have a major impact on a satellite’s electrical performance. Most notably, a number of serious issues arise from the inability to directly modify satellite systems that operate in orbit. Accurate analysis of electrical performance is crucial for mitigating the issues arising from the low-pressure discharge phenomenon. Complex structures, such as intricate features and curved structures, are frequently used in satellite systems’ enormous microwave components. In this case, the finite-difference time-domain (FDTD) approach proposes the hybrid implicit–explicit (HIE) algorithm with a domain decomposition method to effectively simulate complex structures under the low-pressure discharge phenomenon. The bilinear transform method is adjusted in accordance with the implicit equations for the anisotropic magnetized plasma environment caused by the discharge. To end unbounded lattices, a higher-order perfectly matched layer is used at the boundary. An example of a microwave connector structure is used to show how well the algorithm performs electrically. According to the findings, the suggested algorithm behaves in a way that is consistent with both the traditional algorithm and the experiments. Furthermore, the phenomenon of low-pressure discharge has a notable impact on the electrical performance of microwave components.

Modeling Microwave Connectors Used as Signal Launchers for Microstrip Lines of Different Widths

A full characterization and modeling methodology for the electrical transitions introduced by coaxial connectors serving as interfaces for accessing microstrip (MS) lines is presented and verified up to 40 GHz. The associated two-port network parameters are obtained from measurements performed on MS lines of different lengths. Subsequently, two circuit models for the transition are proposed and used to assess the performance of the connector transition as the lines vary in width.

Design of robust and low‐loss 3‐D printed double‐ridged waveguide to microstrip transition

In this paper, we present a new microstrip to waveguide transition design for interfacing printed circuit board (PCB) microstrip transmission lines with 3-D printed metallised-plastic waveguide components. Compared with traditional metal waveguides, interfacing with plastic-based waveguides are challenging due to thermal and mechanical constraints. Despite the development of 3-D printing technology, the precision of 3-D printed waveguides is not as good as the machined metal counterparts. This is critical for microwave components and must be considered in the design process. To minimise the effect of non-ideal waveguide components, a design methodology minimising sensitivity to geometrical variations in the 3-D printed parts is proposed. By sandwiching the PCB between two waveguide sections and optimising the waveguide impedance transformation geometry, the design shows very low insertion loss. It is mechanically robust, cost effective and simple to manufacture. In full system integration, this transition design eliminates the need for expensive microwave cabling and connectors by directly mounting the waveguide to the microwave transceiver PCB. The proof-of-concept transition structure presented in this paper is suitable for microwave applications where low cost and low weight are critical, for example, drone-based radars for remote sensing and space-born satellites. The fabricated structure is characterised using two sets of waveguide components manufactured with different 3-D printing technology and metallisation process': conductive spray painted Fused Deposition Modelling—Polylactic Acid (PLA Painted) and copper electroplated Stereolithography (SLA Plated). Scattering parameters for both types are measured in a short and back-to-back configuration, obtaining the reflection coefficient and insertion loss. Measurements indicate good agreement with modelling and measured performance exceeding prior art. The measured operation band of the Copper-SLA version is 2.9–7.2 GHz with <−10 dB reflection coefficient (S11) and with an insertion loss (S21) of <0.7 dB. With the reduced metallisation and surface quality of the Spray-PLA model, the band is shifted to 3.0–8.0 GHz with an increased S21 of <1.8 dB. The results demonstrate the importance of adopting new transition structures for 3-D printed microwave components where the surface roughness, metallisation quality, and mechanical properties are less optimal. By combining the proposed design with 3-D printed metallised microwave components, very light weight and cost-effective antenna systems can be implemented. Radiation measurements of a 3-D printed double ridge horn antenna connected to the waveguide and used as a feed are also presented, where the operation band is measured to 3–10 GHz with a gain of 5–10 dBi.

Characterizing Microwave Connectors Over Temperature: Thermal-Stable Standards and Characterization Method

In this article, an effective method to characterize microwave connectors over temperature is presented, which can be useful for accurate characterization of devices or materials under temperature stress. First, calibration standards made of thermal-stable RF laminate are used, allowing for assuming constant standard coefficients over temperatures and greatly simplifying the process. Second, all the standards are measured concurrently with a four-port VNA for each temperature of interest, avoiding additional errors due to temperature difference or uncertainties caused by connector reconnections in a sequential measurement. Finally, a linear characterization formulation is employed, enabling an error sensitivity analysis. From the analysis, one is able to identify error-resilient standard-equation combinations, to do the data sanity check, and more importantly to determine the optimal standard length toward a wide effective bandwidth. An end-launch connector is characterized at 0 °C–100 °C, showing the effectiveness and usefulness of the proposed method.

Design of high-performance dual-polarized rectenna for microwave wireless power transmission

This paper presents a 5.8 GHz high-efficiency dual-polarized rectenna for microwave wireless power transmission. The rectenna consists of a 5.8 GHz dual-polarized receiving antenna and a 5.8 GHz class-F rectifier. A metallic probe is used to integrate the receiving antenna and the rectifier. The receiving antenna is a 2×2 microstrip array antenna and the metal ring loading technology is adopted to improve the rectenna’s impedance bandwidth and robustness. The metal probe instead of the conventional microwave connector and cable is utilized to realize the integration of receiving antenna and rectifier circuit, thus simplifying the structure and reducing the weight, loss and cost of the rectifier antenna. A prototype of the dual-polarized rectenna is fabricated and its rectifying efficiency is measured and compared with the linear-polarized rectenna with the same aperture area. The measured results show that the maximum conversion efficiency of the dual-polarized rectifying antenna reaches 76.8% under the optimum incident power density of 1.47 mW·cm−2. Compared to the linear-polarized rectenna, when the polarization direction of the incident wave varies from 0° to 90°, the conversion efficiency of the rectenna antenna is always above 62% with stable DC output and the rectenna antenna exhibits excellent all-polarization receiving rectification performance.

Принципы реализации соосных СВЧ-соединителей для современных радиоэлектронных систем

Many modern radioelectronic systems are based on antenna arrays such as APAA (active phased array antenna) or DAAR (digital active array antenna), which require specialized connectors of new types and design solutions for the input/output of the microwave signal. The aim of this work is to improve the performance and reliability of coaxial microstrip connectors and coaxial waveguide transformer connectors of longitudinal type. The paper analyzes the arrangement principles of antenna feeders in modern radioelectronic systems with microwave connectors and substantiates the need to create new types of specialized microwave connectors. The authors demonstrate the issues that arise when using known coaxial microstrip connectors with threaded joints in antenna arrays. The paper considers the principles of implementing a cut-in microwave connector with hyperboloid contacts and its advantages, as well as the design of such a connector, i. e., the block coaxial microstrip transition and the cable part. The main technical parameters of cut-in microwave connectors are given. Using the analysis of the advantages and drawbacks of the known coaxial waveguide junction, the authors develop the requirements for the creating new microwave connectors of this type. The paper presents a design version of the longitudinal coaxial waveguide transformer connectors and their main characteristics.The considered design versions of the cut-in coaxial microstrip connector and the longitudinal coaxial waveguide transformer connector were manufactured and their characteristics were carefully studied. Analysis of the research results and measured parameters allow asserting that the proposed technical solutions are reliable, reproducible, can be mass produced, and thus can be recommended for use in modern radioelectronic systems.

Most important factors affecting radio frequency characteristics of microwave cable assemblies

The evolution of satellite communications systems results in more stringent on-board and ground equipment specifications for gain/temperature, performance variations, impedance matching quality. The use of cable assemblies capable to meet the increased requirements is essential for signal transmission between the units without any performance degradation. Taking into account the variety of microwave cables and connectors it is necessary to establish the selection criteria for parts and techniques of manufacturing microwave cable assemblies for satellite communications systems. This paper contains the analysis of the technological aspects of cable assemblies manufacturing which impact the radio frequency characteristics of end items.

A high-density customizable microwave vacuum feedthrough for cryogenic applications.

We have designed, constructed, and tested an electrical vacuum feedthrough that can carry a large number of microwave signal lines, has high vacuum compatibility, and is highly customizable. We found that it had a leak rate of approximately 10-7 Pa L/s (7.5 × 10-9 torr L/s), making it suitable for high-vacuum systems such as cryostats. The feedthrough is low-cost, and the printed circuit board-based design allows the choice of any surface-mountable microwave connector. We additionally verified operation through consistent use on a real cryogenic system and verified the mechanical robustness of the feedthrough.

Broadband Measurement of Substrate Complex Permittivity Using Optimized ABCD Matrix

In this paper, a novel two-transmission-line method based on optimized ABCD matrix for broadband and continuous substrate dielectric characterization is presented. The original single-line algorithm is firstly discussed and simulated, while the measurement shows that the extracted parameters are far from the actual values due to the presence of microwave connectors and transition mismatches. Therefore, a modified two-line algorithm based on the optimized ABCD matrix is proposed for ungrounded coplanar waveguide (UGCPW) configuration, which is very suitable for electroplating circuits with a consistent conductor layer on newly developed substrates. A comprehensive procedure to calculate the total line attenuation, phase number, characteristic impedance, substrate dielectric constant, and dielectric loss tangent is described. Since both conductor and radiation losses are taken into account, the extracted results show consistency within a single-digital percentage with the reference values. The analysis of the measurement uncertainty and the related uncertainty budgets for the derived dielectric results are also presented. The proposed method is expected to be applied to any transmission lines with arbitrary characteristic impedance, without a prior knowledge of substrate dielectric constant, and no additional calibrations are required other than the calibration kit for Vector Network Analyzer (VNA).

Effects of vibration on passive intermodulation of microwave connector

AbstractThis paper investigates the generation of passive intermodulation (PIM) in coaxial connectors during vibration. A series of experiments were designed and the simulation model and method were proposed for understanding these phenomena. We found that PIM is mainly influenced by the contact stress and contact surface roughness during vibration. Thus, a power spectral density method is presented to identify the roughness parameter of contact surface based on the Weierstrass–Mandelbrot model, and the simulation model and method were verified by the relative experiments. Eventually, some suggestions for engineering application were provided.

A new criterion to quantify the DC and RF electrical response of an electrical contact subject to fretting wear

Microwave connectors are extensively used in numerous industrial applications, including modern means of transport such as aviation and car industries. Connectors are subjected to vibrations and micro-displacements in the contact interface which lead to fretting wear damage. The present study investigated the influence of fretting wear on the transmitted high-frequency signal. A new structure suitable for radiofrequency (RF) measurements, comprising a cross-cylinders specimen adapted on a transmission line, was designed for fretting tests. An electrical contact transmitting a radiofrequency signal was modeled by an RLC (resistor, inductor and capacitor) equivalent electrical circuit. Various coating materials were tested: tin (Sn), white bronze (WB), gold (Au) and silver (Ag). The radiofrequency signal attenuation (insertion loss) and DC electrical contact resistance (ECR) evolutions using a four wire method were measured simultaneously as a function of fretting cycles. The threshold criterion for contact damage in the radiofrequency band was defined as a 0.1 dB increase in signal attenuation. The corresponding DC ECR failure (i.e., NcRF=NcDC,RF) was established for a ECR threshold about ΔRRF = 40mΩ whatever the studied material. Hence the RF failure can be established from a simple DC analysis. SEM and EDX analyses of debris layer confirm that as for Micro Cut (MC) threshold (ΔRMC = 4 mΩ), the fretting scar at the RF failure is characterized by a quasi-elimination of noble elements (Au or Ag) and the formation of an insulating oxide debris layer. However, the transition from MC to RF failure appears to be induced by a drastic increase of the proportion of low conducting copper oxides.

Microwave Connector De-Embedding and Antenna Characterization [Education Corner

This article describes a systematic procedure for microwave connector de -embedding in a single -port antenna system. Coaxial connectors are a much -used medium to probe the electrical properties of radio -frequency (RF) components. However, connectors impact the magnitude and phase response of the device under test (DUT). Thus, it is essential to de -embed the connector properties to access the actual characteristics of the DUT. Various de embedding techniques reported in the literature considered the DUT as a two port device.

Passive Intermodulation of Contact Nonlinearity on Microwave Connectors

For the passive intermodulation (PIM) problem of nonlinear contact on microwave connectors, an effective method is presented to improve the computational accuracy of PIM. First of all, the contact stress distribution on contact surface is analyzed by finite-element method based on the Weierstrass-Mandelbrot model. The contact stress and real area of contact are evaluated under different loading conditions. Then, the electrical parameters of physical effects of nonlinear contact are derived based on the electric contact theory and the physical effects of metal-metal microcontact. Finally, the nonlinear I-V relation is established from the microcontact equivalent circuit, and the third-order PIM power level generated by contact nonlinearity is revealed in analytic form. The analytic results are verified by the PIM test experiments. This work provides a novel way for PIM calculation of rough surface contact.

Microwave cavity-enhanced transduction for plug and play nanomechanics at room temperature.

Following recent insights into energy storage and loss mechanisms in nanoelectromechanical systems (NEMS), nanomechanical resonators with increasingly high quality factors are possible. Consequently, efficient, non-dissipative transduction schemes are required to avoid the dominating influence of coupling losses. Here we present an integrated NEMS transducer based on a microwave cavity dielectrically coupled to an array of doubly clamped pre-stressed silicon nitride beam resonators. This cavity-enhanced detection scheme allows resolving of the resonators' Brownian motion at room temperature while preserving their high mechanical quality factor of 290,000 at 6.6 MHz. Furthermore, our approach constitutes an 'opto'-mechanical system in which backaction effects of the microwave field are employed to alter the effective damping of the resonators. In particular, cavity-pumped self-oscillation yields a linewidth of only 5 Hz. Thereby, an adjustement-free, all-integrated and self-driven nanoelectromechanical resonator array interfaced by just two microwave connectors is realised, which is potentially useful for applications in sensing and signal processing.

Compact 2.45GHz microwave ion/atom source

Characteristics of a microwave driven 3.4 cm diameter compact ion/atom source equipped with permanent magnets were tested. The source can be mounted to a standard copper gasket flange, and microwave power is supplied through an N-type microwave connector. The ion source plasma was observed through an ion extraction hole with an optical emission spectrometer. Peak height of an optical line spectrum emission corresponding to atomic nitrogen increased in proportion to the microwave input power. Quadrupole mass spectrometer showed that N(+) and N(2)(+) were the dominant species in the extracted ion beam. Nitrogen ion current density of 0.23 mA/cm(2) was obtained with only 10 W discharge power and 6 x 10(-3) Pa source surrounding pressure.

Microwave connector characterization

Coaxial connectors can be used either to probe the electrical properties of microwave circuits (e.g., microstrip, stripline) or as a permanent interface to the circuit. When used as a permanent interface, connectors can degrade circuit performance unless their electrical properties are characterized and accounted for during circuit design. Although it is more common to characterize microwave devices using scattering parameters (Collin, 1966) S <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ij</sub> , we have chosen to utilize impedance parameters since they simplify the derivation of equations presented in this article. The proposed measurement-based method for connector characterization is exact in the sense that its theoretical foundation uses no approximations or assumptions

Ultra-high frequency monolithically integrated quantum well infrared photodetector up to 75 GHz

An integrated quantum well infrared photodetector for ultra-high speed and frequency sensing in the mid-infrared has been developed. The photodetector is mounted on a microwave connector with either a ‘K’ or ‘V’ connector. The device was characterised at a temperature of 100 K by optical heterodyne generation of photocurrent in the frequency range DC to 75 GHz. Photoresponse at 75 GHz was approximately 30% that at DC, indicating very fast performance.

マイクロ波中和器の放電室内部測定

A microwave neutralizer was developed in Institute of Space and Astronautical Science. Plasma properties in the discharge chamber of the neutralizer were measured using Langmuir probe and a microwave connector called bias-T. A dense plasma over the cut off density of 2.2×1011cm-3 was observed at the electron extraction orifice. To investigate the endurance problem, an erosion rate was measured using three types of microwave neutralizer, changing the magnetic field strength and chamber length as parameters.

Finite‐difference — time‐domain analysis of a high‐frequency microwave connector

AbstractIn this study, the finite‐difference‐time‐domain method (FDTD) is used to analyze a complex packaging component, namely, a high‐frequency microwave connector. Because the FDTD technique is easy to use and very flexible, it can be employed to analyze packaging components whose geometrical configurations are highly complex. In contrast, other approaches, for example, the method of moments (MoM), the method of lines (MoL), and the finite‐element method (FEM), are more difficult to apply to complex geometries. In this article we employ the FDTD method to investigate the scattering parameters of a microwave connector and validate the numerical results by comparing them with measured data. © 1995 John Wiley &amp; Sons, Inc.

Scattering parameters of SMA coaxial connector pairs

A technique is described for making reflection and insertion loss measurements on microwave connectors, without the need for reference to calibrated or precision standards. The effects of connectors used in the measuring system are removed from the results, thus providing a means for testing and selecting cables from a group for specific critical applications. Results are given for a group of eight sections of Type 141 solid dielectric line having SMA connectors, and generic behavior is predicted for the SMA connector.