Coplanar Waveguide Transmission Line Research Articles

The Use of Coplanar Transmission Lines for Protecting Receiving Antenna Systems from Powerful Electromagnetic Radiation in a Wide Frequency Range

The goal of the work is to expand the frequency range of operation of coplanar waveguide transmission lines as broadband high-speed superconducting protection devices against powerful ultrashort electromagnetic radiation, and to apply them in antenna devices of radio electronic systems designed to ensure the reliable operation of critical infrastructure facilities. The aim is achieved by solving the following tasks: investigating the electrophysical properties of coplanar transmission lines, in particular, capacitance, surface and wave resistance in different phase states that arise under the influence of powerful electromagnetic radiation, and determining the main factors for effective protection in a wide frequency range, designing protective devices. The most important result is the establishment of the possibility of using coplanar transmission lines as protection devices in a wide frequency range up to 100 GHz, as well as the establishment of the dependence of their main characteristics on the design parameters of the superconducting protection device. The significance of the obtained results consists of solving a complex problem of providing protection of antenna systems against powerful ultrashort radiation by establishing an analytical relationship between the electrophysical parameters of coplanar waveguide transmission lines, which are in different phase states determined by the influence of powerful electromagnetic radiation, and their design parameters. The peculiarity of the obtained results is in the clarification of the dependence of the wave resistance of the coplanar waveguide transmission lines in superconducting, mixed, and normal phase states on the change of their active component of surface resistance, determined in turn by the design characteristics of the protective device. The difference from the known works lies in obtaining relationships for determining the wave resistance of protective devices in different phase states.

A Low Insertion Loss Wideband Bonding-Wire Based Interconnection for 400 Gbps PAM4 Transceivers

This paper proposes a design of high-speed interconnection between optical modules and electrical modules via bonding-wires and coplanar waveguide transmission lines on printed circuit boards for 400 Gbps 4-channel optical communication systems. In order to broaden the interconnection bandwidth, interdigitated capacitors were integrated with GSG pads on chip for the first time. Simulation results indicate the reflection coefficient is below -10 dB from DC to 53 GHz and the insertion loss is below 1 dB from DC to 45 GHz. Both indicators show that the proposed interconnection structure can effectively satisfy the communication bandwidth requirements of 100-Gbps or even higher data-rate PAM4 signals.

On-Glass Grid Structure and Its Application in Highly-Transparent Antenna for Internet of Vehicles

In this paper, a low-cost printed-circuit-board (PCB) technology-based on-glass grid structure and its application in highly-transparent antenna for the internet of vehicles are presented. Firstly, a diamond-shaped grid structure on a glass substrate for high optical transparency (OT) is studied. To show the feasibility, two equal-length co-planar waveguide (CPW) transmission lines (TMLs) with conventional solid and the proposed grid structure are compared. It is found that identical electrical length and comparable performance of the two TMLs are obtained. The relationship between OT and electrical performance is also derived. In the next place, the application of the on-glass grid structure in the highly-transparent antenna design is explored, and the detailed fabrication process is presented. Finally, for demonstration, a CPW-fed wideband end-fire on-glass highly-transparent antenna covering the 5.8-GHz vehicle-to-vehicle band is designed, fabricated, and measured. Ultra-broad impedance bandwidth of 64.6% (3.08–6.02 GHz), wide H-plane beamwidths of over 146°, high antenna efficiencies of over 71.9%, and high OT of 69.8% are achieved. Easily fabricated with mature PCB technology and integrated on the vehicle windows, the proposed structure provides a low-cost highly-transparent solution for the internet of vehicles.

Dual-band filter design based on hourglass-shaped spoof surface plasmon polaritons and interdigital capacitor structure

In this paper, a dual passband filter with spoof surface plasmon polaritons (SSPPs) and interdigital capacitance structure loaded on a coplanar waveguide (CPW) is proposed. First, the hourglass-shaped SSPP unit-cell structure and the interdigital capacitor structure are introduced on the coplanar waveguide transmission line to obtain high fractional bandwidth and low insertion loss passband characteristics. Then, a dual passband filter is formed by loading the interdigital capacitor loop resonator to excite the trapped waves. The simulation results show that the proposed dual passband filter has excellent upper sideband rejection and dual passband filtering performance. The fractional bandwidths of the two passbands of the design are 46.8% (1.49–2.40 GHz) and 15.1% (2.98–3.63 GHz), respectively, which can achieve more than –40 dB rejection in a range of 4.77–7.48 GHz. The upper cutoff frequency and lower cutoff frequency of the two passbands can be independently regulated by changing the structural parameters of the proposed filter. In order to gain a more in-depth understanding of the operating principle of the dual passband filter, the corresponding dispersion curves and electric field distribution, LC equivalent circuit analysis are given. Finally, the prototype of the designed filter is fabricated according to the optimized parameter values. The experimental results are in good agreement with the simulation ones, indicating that the proposed dual-passband filter is of great importance in implementing microwave integrated circuits .

Signal Integrity Analysis of RF Probe Card for WLCSP Testing Using Polyimide-Based Grounded Coplanar Waveguide Transmission Lines

Signal Integrity Analysis of RF Probe Card for WLCSP Testing Using Polyimide-Based Grounded Coplanar Waveguide Transmission Lines

THz Thin Film Varactor Based on Integrated Ferroelectric HfZrO2.

In this paper, we present a broadband microwave characterization of ferroelectric hafnium zirconium oxide (Hf0.5Zr0.5O2) metal-ferroelectric-metal (MFM) thin film varactor from 1 kHz up to 0.11 THz. The varactor is integrated into the back-end-of-line (BEoL) of 180 nm CMOS technology as a shunting capacitor for the coplanar waveguide (CPW) transmission line. At low frequencies, the varactor shows a slight imprint behavior, with a maximum tunability of 15% after the wake-up. In the radio- and mmWave frequency range, the varactor's maximum tunability decreases slightly from 13% at 30 MHz to 10% at 110 GHz. Ferroelectric varactors were known for their frequency-independent, linear tunability as well as low loss. However, this potential was never fully realized due to limitations in integration. Here, we show that ferroelectric HfO2 thin films with good back-end-of-line compatibility support very large scale integration. This opens up a broad range of possible applications in the mmWave and THz frequency range such as 6G communications, imaging radar, or THz imaging.

Antiferroelectric-like Behavior in a Lead-Free Perovskite Layered Structure Ceramic.

Antiferroelectric (AFE) materials have been intensively studied due to their potential uses in energy storage applications and energy conversion. These materials are characterized by double polarization-electric field (P-E) hysteresis loops and nonpolar crystal structures. Unusually, in the present work, Sr1.68La0.32Ta1.68Ti0.32O7 (STLT32), Sr1.64La0.36Ta1.64Ti0.36O7 (STLT36), and Sr1.85Ca0.15Ta2O7 (SCT15), lead-free perovskite layered structure (PLS) materials, are shown to exhibit AFE-like double P-E hysteresis loops despite maintaining a polar crystal structure. The double hysteresis loops are present over wide ranges of electric field and temperature. While neutron diffraction and piezoresponse force microscopy results indicate that the STLT32 system should be ferroelectric at room temperature, the observed AFE-like electrical behavior suggests that the electrical response is dominated by a weakly polar phase with a field-induced transition to a more strongly polar phase. Variable-temperature dielectric measurements suggest the presence of two-phase transitions in STLT32 at ca. 250 and 750 °C. The latter transition is confirmed by thermal analysis and is accompanied by structural changes in the layers, such as in the degree of octahedral tilting and changes in the perovskite block width and interlayer gap, associated with a change from non-centrosymmetric to centrosymmetric structures. The lower-temperature transition is more diffuse in nature but is evidenced by subtle changes in the lattice parameters. The dielectric properties of an STLT32 ceramic at microwave frequencies was measured using a coplanar waveguide transmission line and revealed stable permittivity from 1 kHz up to 20 GHz with low dielectric loss. This work represents the first observation of its kind in a PLS-type material.

C-Band Linear Polarization Metasurface Converter with Arbitrary Polarization Rotation Angle Based on Notched Circular Patches

This paper presents a linear polarization metasurface converter with arbitrary polarization rotating angle and stable oblique incident response, which is based on the concept of linear-to-circular polarization decomposition and recombination. A metasurface unit cell is proposed using a notched circular patch with two metallized vias connected to the bottom-layer coplanar waveguide (CPW) transmission lines. By changing the length of the two transmission lines, different polarization rotation angle may be realized. The proposed metasurface polarization converter is theoretically analyzed and full-wave simulated. A 45∘ metasurface polarization converter with 8×8 unit cells is designed and experimentally demonstrated. The experimental results agree well with the simulation, showing that the proposed metasurface polarization converter can achieve a high polarization conversion ratio (PCR) larger than 85% under up to 50∘ oblique incident wave.

Circular split‐ring resonator‐based sensor for dielectric constant measurement

AbstractThis paper presents the development of a metamaterial‐based microwave sensor for dielectric constant measurements. The sensor is constructed with a circular split‐ring resonator on one side and a coplanar waveguide transmission line on the other side. The proposed sensor has a size of 35 mm × 35 mm × 1.27 mm and resonates at 3.31 GHz. The sensor is fabricated on a RO3210 substrate with a dielectric constant of 10.2 and a loss tangent of 0.003. Both the simulation and experimental measurements show a linear relationship between the shift of the resonance frequency and the dielectric constants of the test samples, with a coefficient of determination R2 above 0.99. The dielectric constant of an unknown material can therefore be easily estimated using the inverse linear regression model. To validate the performance of the sensor, three known substrate materials, namely, Rogers RT6002, FR4, and Rogers TMM10, were used as test samples. The measured dielectric constants for these three materials were 2.8045, 4.3775, and 8.8719, respectively. The results agree closely with those indicated in the data sheets, with discrepancies of less than 5%.

Current Distribution and Kinetic Inductance of Coplanar Waveguide Transmission Lines

Analysis of superconducting circuits requires knowledge of current density distribution in the film cross section. This article aims to investigate the current density distribution in superconducting coplanar waveguides (SCPWs), a basic component with increasing use in microwave integrated circuits. In this regard, first, the CPW is mapped to a pair of parallel plates and the vector potential is described through the Green's function concept. Then, based on the Green's function and utilizing London's second equation, an integral equation is formed which yields the current density distribution. The procedure is verified by COMSOL Multiphysics software. Examining the current density for several SCPWs shows that as the gap is reduced, the SCPW experiences much more current density especially at the edges. Based on the proposed procedure, the kinetic inductance of SCPW is examined, which is another focus of the article. In this article, for several CPWs with different aspect ratios, the kinetic inductance is evaluated and discussed. Results show that as the ratio is increased, the kinetic inductance is decreased.

Design and simulation of continuous tuning band stop filter by2-D periodic defected ground structure

In this paper, the design and simulation of a continuous tuning bandstopfilter (BSF) is done by using two-dimensional (2-D) periodic DGS for the coplanar waveguide (CPW) transmission line. The proposed BSF filter structure has DGS cells on the ground plane of the CPW transmission line. This structure can easily be designed for another frequency band by changing the number of periodic DGS unit cells. This BSF has a fixed bandwidth of 8.2 GHz over a wide range of frequencies (16–26) GHz.The tunability of the BSF is achieved by moving plates, which are kept above the substrate of the CPW. The size of these plates is the same as the size of the DGS cell. The tunability of the BSF is observed while changing the distance between the metal plates and substrate in the up position. In the down position the metal plates are covered by the DGS cells, then the filter act as a normal transmission line. The extraction of the equivalent circuit model parameters has also been derived. The electromagnetic (EM) and equivalent model simulations are done with the HFSS and ADS tools, both these simulations have a good agreement with each other. From this, the proposed BSF can be used for satellite and radar communication in K band frequency range.

Low Profile Dynamic Patch Antenna Array With High-Intensity Radiation Fields (HIRF) Protection

A 1-bit low-profile patch antenna array integrating beam scanning and adaptive high-intensity radiation fields (HIRF) protection is proposed in this paper. Each antenna element consists of two dielectric layers, two radiation patches, a ground plane, and a feeding network. By electronically controlling a pair of coding diodes in the same direction, the antenna element can achieve 180 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^\circ$</tex-math></inline-formula> phase difference, producing two logical states, namely “0” and “1”. It has good beam scanning capability in the range of −60 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^\circ$</tex-math></inline-formula> to 60 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^\circ$</tex-math></inline-formula> . When the proposed antenna is exposed to HIRF, the protective diodes mounted over the grounded coplanar waveguide (GCPW) transmission line are triggered, dramatically reducing the overall gain of the antenna array. By optimizing design, the element possesses a bandwidth of 8.8 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\sim$</tex-math></inline-formula> 9.3 GHz. The grating lobe of the antenna array is suppressed by 17.5 dB thanks to the adoption of the non-uniform feed. The simulation results indicate that the proposed antenna element and array have a high isolation degree of 22.4 dB and 23.2 dB when exposed to HIRF, respectively. Finally, a prototype of the antenna is fabricated, and the validity of the proposed design is experimentally verified. The experimental results are in good agreement with the simulation results, demonstrating the validity of the proposed design.

Characterization of high impedance of multilayer coplanar waveguide transmission line design for integration with nanodevices

Terahertz technology has recently attracted the attention of the researchers due to its wide range of applications such as security and military, biomedicine and health care, astronomy and biology. There are many scrutinized research papers among the terahertz applications with nanodevices such as self-switching devices. They need monolithic microwave integrated circuits for integration. It is evident that the system impedance of transmission lines is 50 Ω. However, the main limitation of self-switching diodes is high level of impedance in megaohms which is a huge value and is not so easy to implement. Paper focuses on the design and simulation of the coplanar waveguide transmission line structures with higher impedance by applying multilayer technology for the integration with self-switching diodes. Using multilayer technology in design allows wide range of impedances. Two approaches have been targeted such that meets all the requirements of integration with nanodevice. First approach is a widening the gap of the polyimide dielectric layers used in the fabrication of these components. Several design structures have been considered such as positioning the location of signal and grounds contacts with respect to the position of the dielectric layers. As the result the highest characteristic impedance of about 90 Ω was achieved at operating frequency of 110 GHz. Secondly, novel coplanar waveguide transmission line structure was investigated where the V – shape structure was joined with the signal elevated structure. The terahertz application research may effect on high data transmission rate of no less than 10 GBit/s and thereby in increase of traffic volume.

Waveguide-coupled heterodyne terahertz detector based on AlGaN/GaN high-electron-mobility transistor

We report a room-temperature, low output impedance, broad intermediate-frequency (IF) bandwidth field-effect terahertz detector based on an AlGaN/GaN high-electron-mobility transistor (HEMT) integrated in a metal waveguide. The waveguide detector equips a pair of quasi-Yagi antenna probes that are used to couple the terahertz energy to the HEMT channel. The gate is configured as an asymmetric edge-coupled coplanar waveguide transmission line. This terahertz electric field is asymmetrically distributed in the channel along the edges of the transmission lines. The responsivity and noise for direct and heterodyne detections are characterized and analyzed at different local oscillator (LO) powers. The noise-equivalent power in direct detection is below 189 pW/Hz1/2. Operated in a heterodyne mode with a LO power of −3 dBm, the detector offers a conversion loss less than 55 dB in a frequency band of 320–340 GHz. The channel in a form of transmission line performs the broad IF bandwidth, which is increased to gigahertz range (3 GHz), and reduces the output impedance to 377 Ω which is about 20 times lower than previously reported. The transmission-line impedance could be optimized together with the distribution of the terahertz electric field in the gated channel to reduce the conversion loss.

Localized Backside Etching Structure of SOI Substrates on Total Ionizing Dose Effect Hardening for RF Applications

In this work, the localized backside etching (LBE) structure is introduced as a strategy for total ionizing dose (TID) irradiation hardening. Immunity to TID-irradiation-induced radio frequency (RF) property degradation is observed for the first time in SOI substrates with the LBE structure. Identical co-planar waveguide transmission lines (CPW TLines), crosstalk characterization structures, and planar spiral inductors are designed and fabricated on different 8-in SOI wafers to characterize the RF properties of substrates. Electrical characterization in the frequency ranges from 100 MHz to 40 GHz reveals that the LBE structure is beneficial to suppressing the parasitic surface conduction (PSC) effect, which will lead to better RF properties of SOI substrate. It is shown that under <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">60</sup> Co <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\gamma $ </tex-math></inline-formula> -ray irradiation, RF losses are significantly increased in the case of conventional substrates. In contrast, LBE substrates are almost insensitive to TID irradiation due to suppression of PSC. A developed physical model is proposed to characterize the behavior of inductors under PSC and TID effects, and the improvement by LBE structure on RF TID tolerance is separated through model parameter extraction.

A detailed performance analysis of a novel UWB flexible monopole antenna realized with airbrush technique for different technologies

In this article, a detailed performance analysis of a novel flexible monopole antenna with a 141.46% impedance bandwidth in the 2.4–14 GHz ultrawideband (UWB) range is present. The antenna is fabricated on a flexible Kapton substrate with compact geometry for different technology applications under different bending conditions. The airbrush printed technique was preferred due to its advantages such as easy production, conductivity control, and no loss of surface waves. The antenna has dimensions of 82 × 57 × 0.125 mm3 and is fed by a coplanar waveguide transmission line. All necessary antenna simulations are performed using Computer Simulation Technology (CST). According to the positions of identical antennas face to face, face to side, side to side, time-domain analysis is performed for the impact response analysis. The transmission coefficient characteristics (S 21) and the group delay are measured for various bending conditions. Time and frequency domain analyzes show that the proposed UWB antenna has the much-needed stable performance in UWB antenna. The proposed UWB antenna has good performance over the operating spectrum for a flat and bending configuration.

Novel High Isolation and High Capacitance Ratio RF MEMS Switch: Design, Analysis and Performance Verification

In this paper, a novel high isolation and high-capacitance-ratio radio-frequency micro-electromechanical systems (RF MEMS) switch working at Ka-band is designed, fabricated, measured and analyzed. The proposed RF MEMS switch mainly consists of a MEMS metallic beam, coplanar waveguide (CPW) transmission line, dielectric layer and metal–insulator–metal (MIM) fixed capacitors. The measured results indicate that the insertion loss is better than 0.5 dB at 32 GHz, and the isolation is more than 35 dB at the resonant frequency. From the fitted results, the capacitance ratio is 246.3. Compared with traditional MEMS capacitive switches, this proposed MEMS switch exhibits a high capacitance ratio and provides a wonderful solution for cutting-edge performance in 5G and other high-performance applications.

Circuit Analysis of a Coplanar Waveguide (CPW) Terminated With a Step-Impedance Resonator (SIR) for Highly Sensitive One-Port Permittivity Sensing

This paper presents a single-frequency reflective-mode phase-variation microwave sensor devoted to the dielectric characterization of materials. The device is implemented in coplanar waveguide (CPW) technology and consists of two parts: (i) the sensing region, a step-impedance resonator (SIR) as termination of a CPW transmission line, and (ii) the design region, a cascade of high/low impedance quarter-wavelength inverters, used to boost up the sensitivity. By placing the so-called material under test (MUT) on top of the sensing region, the capacitance of the SIR is altered due to the effects of the dielectric constant of the MUT. This modifies the phase of the reflection coefficient seen from the input port, the output variable. From a circuit analysis, it is demonstrated that the sensitivity for small perturbations in the vicinity of the dielectric constant of a reference (REF) material can be optimized by setting the operation frequency of the sensor to the resonance frequency of the SIR loaded with such REF material. The maximum sensitivity in one of the reported sensors is as high as 66.5&#x00B0;, and the main figure of merit, defined as the ratio between the maximum sensitivity and the area of the sensing region expressed in terms of the squared guided wavelength, is FoM = 3643&#x00B0;/&#x03BB;². Such figure of merit represents a significant improvement as compared to the one of the equivalent sensor implemented by means of an open-ended quarter-wavelength sensing line. Such equivalence between the semi-lumped element (i.e., SIR-based) sensor and the fully distributed counterpart is also analyzed in the paper.

50 Ω transmission lines with extreme wavelength compression based on superconducting nanowires on high-permittivity substrates

We demonstrate impedance-matched low-loss transmission lines with a signal wavelength more than 150 times smaller than the free space wavelength using superconducting nanowires on high permittivity substrates. A niobium nitride thin film is patterned in a coplanar waveguide (CPW) transmission line geometry on a bilayer substrate consisting of 100 nm of epitaxial strontium titanate on high-resistivity silicon. The use of strontium titanate on silicon enables wafer-scale fabrication and maximizes process compatibility. It also makes it possible to realize a 50 Ω characteristic impedance across a wide range of CPW widths from the nanoscale to the macroscale. We fabricated and characterized an approximately 50 Ω CPW device with two half-wave stub resonators. Comparing the measured transmission coefficient to numerical simulations, we determine that the strontium titanate film has a dielectric constant of 1.1×103 and a loss tangent of not more than 0.009. To facilitate the design of distributed microwave devices based on this type of material system, we describe an analytical model of the CPW properties that gives good agreement with both measurements and simulations.

Design of a 1×2 CPW Fractal Antenna Array on Plexiglas Substrate with Defected Ground Plane for Telecommunication Applications

In this paper, a fractal antenna array for telecommunication applications is presented. The proposed antenna array is realized on a Plexiglas substrate, has 1×2 radiating elements, and dimensions of 170mm×105mm. The antenna array is composed of two Koch Snowflake patches and is fed by a Coplanar Waveguide (CPW) transmission line. Radiating elements and the ground plane are printed on the top side of the substrate. Defected Ground Structure (DGS) technique is employed to enhance the bandwidth and improve the impedance matching. The proposed antenna array operates at two frequency bands, 1.08-1.32GHz covering the GPS band and 1.7-3.7GHz covering the GSM 1800/1900, UTMS, Bluetooth, LTE, and WiMAX bands. In addition, the antenna has a good performance with efficiency and peak gain of 82% and 6.3dB respectively. These characteristics allow the antenna to be an attractive candidate for telecommunication systems. Design and analysis of different structures were carried out with Ansys HFSS.