Coplanar Stripline Research Articles

Ultra-Wideband Common-Mode Rejection Structure with Autonomous Phase Balancing for Ultra-High-Speed Digital Transmission.

For ultra-high-speed digital transmission, required by 5G/6G communications, ultra-wideband common-mode rejection (CMR) structures with autonomous phase-balancing capability are proposed. Common-mode noise, caused by phase and amplitude unbalances, is one of the most undesired disturbances affecting modern digital circuits. According to the circuit design guides with a typically used differential line (DL) for high-speed digital transmission, common-mode rejection is achieved using CMR filters, and the unbalanced phase, caused by a length difference between the two signal lines of a DL, is compensated by inserting an additional delay line. However, due to nonlinear phase interactions between the two DLs and unbalanced electromagnetic (EM) interferences, the conventional compensation method is frequency-limited at around 10 GHz. To significantly enhance the common-mode rejection level and extend the phase recovery bandwidth, the proposed CMR structure utilizes a planar balanced line (BL), such as a coplanar stripline (CPS) or a parallel stripline (PSL), along with additional conductor strips arranged laterally near the BL. To demonstrate the performance of the proposed BL-based CMR structures, various types of CMR structures are fabricated, and the measurement results are compared with the 3D EM simulation results. As a result, it is proven that the proposed BL-based CMR structures have the capability to reject the common-mode noise with suppression levels of more than 10 dB and to simultaneously recover the phase balance from near DC to over 40 GHz.

Design of Coplanar Stripline Bandpass Filter With Reconfigurable Filter Switch

ABSTRACTThis article has designed a bandpass filter using a coplanar stripline stub (CPS) resonator consisting of open and short‐ended strip lines connected to the PIN diode switches. The use of spurline stub resonators inside CPS results in bandpass and bandstop filters, depending on the PIN diode switch configurations. The work presents a novel circuit architecture aimed at reducing the parasitic resonance of the spurline resonators and acquiring the necessary series stub characteristics. The proposed filter resonates at 6.9–9, 1.7–4.7, and 8.4 GHz when the PIN diodes are forward and reverse‐biased, respectively. It also resonates at 1–2.1, 4.8–5.3, and 6.9–9 GHz when one diode is reverse‐biased, and the other is connected in forward bias. An insertion loss below −0.55 dB and a return loss less than 10 dB have been obtained during simulation and measurement. The designed filter can find different applications for the 1.8 GHz GSM band, 2.4/5.8 GHz (WLAN), 3.6 GHz (WiMAX), long‐term evolution (LTE), and WIFI. The filter can be used in various multi‐frequency systems owing to its compact size. The measured and simulated findings of the proposed CPS spurline stub resonator wideband bandpass filters are substantially consistent.

Ultra-Wideband Vertical Transition in Coplanar Stripline for Ultra-High-Speed Digital Interfaces.

A design method for an ultra-wideband coplanar-stripline-based vertical transition that can be used for ultra-high-speed digital interfaces is proposed. A conventional via structure, based on a differential line (DL), inherently possesses performance limitations (<10 GHz) due to difficulties in maintaining constant line impedance and smooth electric field transformation, in addition to the effects of signal skews, FR4 fiber weave, and unbalanced EM interferences. DL-based digital interfaces may not meet the demands of ultra-high-speed digital data transmission required for the upcoming 6G communications. The use of a coplanar stripline (CPS), a type of planar balanced line (BL), for the vertical transition, along with the ultra-wideband DL-to-CPS transition, mostly removes the inherent and unfavorable issues of the DL and enables ultra-high-speed digital data transmission. The design process of the transition is simplified using the analytical design formulas, derived using the conformal mapping method, of the transition. The characteristic line impedances of the transition are calculated and found to be in close agreement with the results obtained from EM simulations. Utilizing these results, the CPS-based vertical transition, maintaining the characteristic line impedance of 100 Ω, is designed and fabricated. The measured results confirm its ultra-wideband characteristics, with a maximum of 1.6 dB insertion loss and more than 10 dB return loss in the frequency range of DC to 30 GHz. Therefore, the proposed CPS-based vertical transition offers a significantly wider frequency bandwidth, i.e., more than three times that of conventional DL-based via structures.

Cost-Effective Design of Polarization and Bandwidth Reconfigurable Millimeter-Wave Loop Antenna.

A singly fed reconfigurable circular loop antenna is proposed for millimeter-wave (mmWave) communication systems. This antenna's distinctive feature lies in its capacity to adjust both polarization and bandwidth characteristics, a capability made possible by the strategic integration of two PIN diodes. These diodes are engineered to function in various modes, allowing for three distinct polarization states and accommodating two distinct bandwidths. A meticulous alignment of these PIN diodes enables the utilization of a single DC bias network as a highly effective RF choke, which simplifies the design and reduces the associated losses. Additionally, a planar biasing network that consists of coplanar strip-lines (CPS) has been employed eliminating the need for lumped elements. The simple and totally planar configuration offers a choice of right-hand circularly polarized (RHCP) radiation or left-hand circularly polarized (LHCP) radiation at 28 GHz. This is accompanied by impedance matching and axial ratio (AR) bandwidths of 12.9% and 8%, respectively, over the same frequency range with a gain of 7.5 dBic. Moreover, when the PIN diodes are unbiased, the antenna offers linear polarization (LP) over two narrow bandwidths at 27 GHz and 29 GHz featuring a maximum gain of 7.2 dBic. Therefore, the proposed configuration offers three operating modes: wide-band RHCP, wide-band-LHCP, and LP over dual narrow bands. Significantly, simulated results closely align with the measured outcomes, affirming the robustness and accuracy of this design.

On Autonomous Phase Balancing of the Coplanar Stripline as a Feedline for a Quasi-Yagi Antenna

This paper provides a clear demonstration that a coplanar stripline (CPS) as a balanced line can act to re-establish the phase balance in the presence of phase deviation from a 180° distance between two input signal lines connected to the CPS. A half-wave delay line splitter connected to a CPS works as a balun to feed a balanced antenna, such as a quasi-Yagi antenna. This type of balun structure has been widely used to feed balanced antennas with a frequency bandwidth of up to 60%. Nevertheless, no clear explanation has been given regarding how the broadband antennas could be implemented with this type of balun structure. In this paper, through 3D EM simulations and measurements, it is shown that the half-wave delay line splitter indeed only results in the 180° phase balance at one frequency, but the subsequently connected CPS acts to recover the phase balance between the signal lines. The CPS can recover the phase balance within a phase imbalance of ~π/3, which determines the usable bandwidth of this structure. For a demonstration, with a center frequency of 10 GHz, samples of the half-wave delay line splitter connected to a CPS are fabricated and measured.

Picosecond spin-orbit torque-induced coherent magnetization switching in a ferromagnet.

Electrically controllable nonvolatile magnetic memories show great potential for the replacement of conventional semiconductor-based memory technologies. Here, we experimentally demonstrate ultrafast spin-orbit torque (SOT)-induced coherent magnetization switching dynamics in a ferromagnet. We use an ultrafast photoconducting switch and a coplanar strip line to generate and guide a ~9-picosecond electrical pulse into a heavy metal/ferromagnet multilayer to induce ultrafast SOT. We then use magneto-optical probing to investigate the magnetization dynamics with sub-picosecond resolution. Ultrafast heating by the approximately 9 picosecond current pulse induces a thermal anisotropy torque which, in combination with the damping-like torque, coherently rotates the magnetization to obtain zero-crossing of magnetization in ~70 picoseconds. A macro-magnetic simulation coupled with an ultrafast heating model agrees well with the experiment and suggests coherent magnetization switching without any incubation delay on an unprecedented time scale. Our work proposes a unique magnetization switching mechanism toward markedly increasing the writing speed of SOT magnetic random-access memory devices.

Printed Dual‐Frequency Directional Antenna Loaded With Dual‐Parasitic Strip

AbstractIn this paper, the directional antenna is developed to construct the printed dual‐frequency directional antenna for a 1‐GHz/2.3‐GHz dual‐frequency sensor application. An auxiliary dipole element generating the higher resonant mode is set on a primary dipole element introducing the lower resonant mode. The feed balance is also designed to cover the desired frequency between two resonance frequencies, which is based on the microstrip line (MS) to coplanar stripline (CPS) transition. To realize the directional antenna, two reflector elements are utilized, and one of them is a stepped‐width reflector on reducing the size of the antenna. In addition, the parasitic strip works as the lumped element used to obtain good impedance matching. A series of simulations are performed on the MS‐to‐CPS transition, the dual dipole element, the reflectors, and the parasitic strip to determine the optimal antenna design. A prototype is fabricated based on the optimal results of the simulation. Concerning the measured results, the proposed antenna has well unidirectional radiations, good radiation efficiencies, and low cross‐polarization levels at any operating frequencies.

Coplanar Stripline Single Pole Single Throw Switch

Coplanar stripline (CPS) series-connected spurline resonators are terminated with diodes, which can have a voltage applied to them, creating either a short circuit or open circuit. By connecting two spurline resonators in series separated by a quarter-wavelength transmission line, and when the diodes are reverse biased, the total circuit passes the RF power unimpeded. When the diodes are forward-biased, the circuit is a bandstop filter. This creates a CPS RF series switch with an insertion loss of 0.1 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\pm$</tex-math> </inline-formula> 0.1 dB, a reflection coefficient of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$-$</tex-math> </inline-formula> 30 dB, and an isolation of 20 dB. The switch was simulated, fabricated, and measured for both single-element and two-element configurations.

Parametric study of a dual-band quasi-Yagi antenna for LTE application

Due to small size and lightweight properties, the development of microstrip (MS) patch antennas for wireless communication has become one of the mobile application devices in demand in recent years. This has helped to reduce reliance on wired cables. In this paper, a study has been performed on MS antenna by developing a quasi-Yagi structure on a fire retardant-4 (FR-4) substrate with a MS to coplanar strip line (CPS) transition feeding technique. The antenna is designed by using computer simulation technology (CST) to achieve the desired resonant frequency and bandwidth. The proposed dual band quasi-Yagi antenna has impedance bandwidths of approximately 0.3 GHz and 0.22 GHz resonating at 1.80 GHz and 2.60 GHz, respectively, which makes it suitable for long-term evolution (LTE) applications. Eight-director elements in four pairs are constructed to achieve directivity with magnitudes of 6 dB and 8.3 dBi at both resonant frequencies, 1.80 GHz and 2.60 GHz, respectively. Different parametric studies have also been performed to characterize the antenna radiation characteristics. The return loss, voltage standing wave ratio (VSWR), front to back (F/B) ratio and far-field radiation are analyzed and discussed.

Study of Inductive Reactance of a Micro Strip Line Structure with The Spacing Between Two Metal Strip

The Present Paper aims at the study of inductive property developed due to propagation of electromagnetic waves through the structure and its dependence on the spacing between two metal strip and other factors. Due to interaction of electron beam with electromagnetic waves, kinetic energy of electron is increased. Microwaves have become very powerful experimental tools for study of some of the basic properties of materials. There are different structures for the propagation of electromagnetic powers in different modes. The Microwave Integrated circuits (MIC’S) have changed the systems in the present days by replacing large scale waveguides and co-axial component arrays to small light weight assemblies. These introduced microwave striplines, microslotlines, coplanar strip lines and coplanar waveguide etc.

Strong Coupling of aGd3+Multilevel Spin System to an On-Chip Superconducting Resonator

We report the realization of a strong coupling between a Gd$^{3+}$ spin ensemble hosted in a scheelite (CaWO$_4$) single crystal and the resonant mode of a coplanar stripline superconducting cavity leading to a large separation of spin-photon states of 146 MHz. The interaction is well described by the Dicke model and the crystal-field Hamiltonian of the multilevel spin system. We observe a change of the crystal-field parameters due to the presence of photons in the cavity that generates a significant perturbation of the crystal ground state. Using finite-element calculations, we numerically estimate the cavity sensing volume as well as the average spin-photon coupling strength of $g_0\approx$ 620 Hz. Lastly, the dynamics of the spin-cavity states are explored via pulsed measurements by recording the cavity ring-down signal as a function of pulse length and amplitude. The results indicate a potential method to initialize this multilevel system in its ground state via an active cooling process.

Single-Layer Interconnected Magneto-Electric Dipole Antenna Array for 5G Communication Applications

A high-gain and wideband interconnected magneto-electric (ME) dipole on a single-layer PCB substrate is designed for 5G communication applications. Microstrip lines and coplanar striplines (CPSs) serve as transmission lines to connect the ME dipole elements along the E-plane and the H-plane directions, respectively. Impedance matching and sidelobe-level suppression are the key challenges to design a large-scale interconnected ME dipole antenna array. It is shown that impedance matching can be improved by introducing slots and adjusting the width of microstrip lines. Sidelobe level can be enhanced by properly choosing the length of the microstrip lines. A 5 × 5 interconnected ME dipole array is fabricated on a single layer of the RT/duroid 5880 substrate. The proposed antenna exhibits a measured −10 dB impedance bandwidth of 14.5 GHz (52% at 28 GHz) and a maximal peak realized gain of 20.44 dBi at 27.5 GHz with a 3 dB gain bandwidth of 3.5 GHz (12.5% at 28 GHz). The proposed antenna array is a good candidate for 5G communication applications due to its advantages of simple feeding structure, wide bandwidth, high gain, and low profile.

Ultra-Wideband Dual-Polarized Base-Station Antenna With Stable Radiation Pattern

This communication presents an ultrawideband dual-polarized antenna consisting of a main radiator, parasitic elements, and a ground plane. The main radiator is composed of two pairs of dual dipoles, which are cross-arranged and fed by coplanar-strip lines in order to achieve <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\pm \mathrm{45}^{\circ }$ </tex-math></inline-formula> dual-polarization within a wide frequency band. Parasitic elements, including a circular patch and four pairs of dipole strips, are employed for improving the radiation performance in high frequencies, which is very essential for stabilizing the radiation pattern over the entire bandwidth. The proposed antenna can cover the frequency range from 1.7 to 5.1 GHz for both polarizations, corresponding to an ultrawide bandwidth of 100%. The gain and half-power beamwidth (HPBW) are very stable within the entire bandwidth, which are <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$8.2~\pm ~0.7$ </tex-math></inline-formula> dBi and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mathrm{65}^{\circ }\pm \mathrm{5}^{\circ }$ </tex-math></inline-formula> , respectively. The measured results agree well with simulated ones, indicating that the proposed antenna is a very promising candidate for the future base-station communication system.

Broadband dual‐polarized folded dipole antenna with simple feed structure

AbstractA broadband folded dipole antenna for dual‐polarized radiation is presented. It comprises two couples of folded dipoles and a planar reflector. To enhance the impedance matching over broadband, each couple of folded dipoles is parallelly connected by stepped coplanar striplines and then excited by a simple feed structure consisting of a 50‐Ω coaxial cable and a rectangular strip. To stabilize the radiation and further improve the impedance matching during an extremely broadband, a rectangular director is utilized and loaded upon each folded dipole. This antenna provides an extremely broad bandwidth of 77.6% (1.68–3.81 GHz) with return loss &gt;15 dB, and good isolation of larger than 25 dB. It also obtains a steady half‐power beamwidth of 66° ± 4° and a gain of 8.6 ± 0.8 dBi during the broadband. This makes it attractive for mobile communication.

Frequency characteristics of strip modules of the quasi-chaotic signals formation based on bulk nonlinear optical crystals

In this paper the experimental study of frequency dependences of scattering matrix coefficients of strip modules based on a coplanar strip line with partial dielectric filling in the form of bulk non-linear optical crystals of quartz, potassium titanium phosphate (KTP), zinc germanium diphosphide, lithium niobate has been performed. The appearance of the effect of forming quasi- chaotic oscillations in modules containing KTiOPO4, ZnGeP2, LiNbO3 bulk crystals when LFM signals are fed at fast switching of incident wave direction in the receiving and transmitting tract of the vector network analyzer is demonstrared. Parameters of comparative characterization of crystal materials are introduced. The complete phase of the modulus transmission coefficient is determined. The analysis of its physical sense is made, followed by processing complete phase shift, which provides the possibility to develop the algorithm of estimating the frequency dependence of crystal’s relative permittivity. The studied modules may be used as formers of quasi- chaotic microwave signals.

High-Tc Superconducting Josephson Junction Harmonic Mixers with Stub Tuners on Integrated Bowtie Antennas

Ordinary mixers can hardly meet the requirements in terahertz (THz) communications due to the low-power and expensive THz sources. Sensitive harmonic mixers have been widely studied to avoid this problem, owing to the fact that the higher the number of harmonics, the lower the local oscillator (LO) frequency, and the lower the cost. High-Tc superconducting (HTS) Josephson junction (JJ) mixers are performing candidates for THz receiver frontends because of the advantages of excellent sensitivity, wide bandwidth, high harmonic number and low LO power requirement. However, the normal-state resistance of HTS JJ is so low that traditional antennas are difficult to match it. In other words, it is quite a challenge to match the input impedance to a low input impedance for traditional antennas, especially for antennas fed by coplanar striplines (CPSs). In this work, based on the structure of bowtie, two types of stub tuners were integrated to decrease the impedance of the bowtie antenna so as to improve the coupling efficiency between the traditional bowtie antenna and the JJ. Furthermore, HTS YBa2Cu3O7-δ (YBCO) JJ harmonic mixers coupled with the proposed structures and fed by CPSs are fabricated and measured. The measurements show that the JJ mixer coupled with a pair of open-end stubs of the bowtie antenna achieves up to 88 harmonics, with a conversion efficiency of −69.6 dB. In contrast, the JJ mixer coupled with a pair of lumped-element stubs of the bowtie antenna only attains to 30 harmonics, with a conversion efficiency of −73.4 dB. Additional numerical simulations indicate that the coupling efficiency is enhanced when the complex impedance of the antenna is explicitly considered. Compared with other coupled traditional antennas, the JJ mixer with bowtie antenna has the largest harmonic number. This work paves the way for the future application of low-frequency and low-cost LO for THz communications.

Ultra-Wideband Differential Line-to-Balanced Line Transitions for Super-High-Speed Digital Transmission.

A conventional differential line (DL), commonly used on typical digital circuit boards for transmitting high-speed digital data, has fundamental limitations on the maximum signal bandwidth (~10 GHz), mainly due to signal skew, multiple line coupling, and EM interference. Therefore, to support super-high-speed digital data transmission, especially for beyond 5G communications, a practical high-performance transmission structure for digital signals is required. Balanced lines (BLs) can transmit the differential signals with multiple advantages of ultra-wide bandwidth, common-mode rejection, reduced crosstalk, phase recovery, and skew reduction, which enable super-high-speed transmission. In order to utilize the BLs in the DL-based digital circuit, connecting structures between a DL and BLs are required, but the DL-to-BL transition structures dominate the operating bandwidth and signal properties. Therefore, in this paper, properties, and design methods for two ultra-wideband DL-to-BL transitions, i.e., DL-to-CPS (coplanar stripline) and DL-to-PSL (parallel stripline) transitions, are presented. Both implemented DL-to-CPS and DL-to-PSL transitions provide high-quality performance up to 40 GHz or higher, significantly enhancing the frequency bandwidth for the transmission of digital signals while providing compatibility with the DL-based PCBs. The fabricated DL-to-CPS transition performs well from DC to 40 GHz with an insertion loss of less than 0.86 dB and a return loss of more than 10 dB, and the fabricated DL-to-PSL transition also provides good performance from DC to 40 GHz, with an insertion loss of less than 1.34 dB and a return loss of more than 10 dB. Therefore, the proposed DL-to-BL transitions can be applied to achieve super-high-speed digital data transmission with over 40 GHz bandwidth, which is more than four times the bandwidth of the DL, supporting over 200 Gbps of digital data transmission on PCBs for the next generation of advanced communications.

Study of Inductive Reactance of a Micro Strip Line Structure with The Width Metal Strip

In the field of high energy physics, it is often necessary to accelerate electron beams to velocities close to that of velocity of light. Due to interaction of electron beam with electromagnetic waves, kinetic energy of electron is increased. Microwaves have become very powerful experimental tools for study of some of the basic properties of materials. There are different structures for the propagation of electromagnetic powers in different modes. Also, there are various devices for sending massage or signals from one place to another remote place. In the age of Moughal period pigeons were employed for sending massage. Now in the age of modern science &amp; technology, radios, television, telegraphs, satellite, cell phones and mobiles are used for sending the message from one place to other places how far away the Microwave Integrated circuits (MIC’S) have changed these systems in the present days by replacing large scale waveguides and co-axial component arrays to small light weight assemblies. These introduced microwave striplines, microslotlines, coplanar strip lines and coplanar waveguide etc. The design system used for these circuits has also changed from the early “cut &amp; try” methods, using “ruler and knife” to the computer aided design (CAD). The Present Paper aims at the study 0f inductive property developed due to propagation of electromagnetic waves through the structure and its dependence on the width of the metal strip and other factors. Such study involves the characteristics parameters such as characteristics impedence and phase velocity and their variations with width metal strip and its utility in designing different planer devices.

Design and Simulation of Terahertz Apodized Bragg Grating Using Coplanar Stripline Transmission Line a 1 µm-thin Membrane

A guided-wave THz System-on-Chip THz System-on-Chip (TSoC) is emerging as an attractive alternative to the routine free-space THz systems to reduce physical bulk, propagation loss, pulse dispersion and cost of free-space THz systems. Recently, our research group succeeded in demonstrating a novel waveguided TSoC based on the coplanar stripline Coplanar Stripline (CPS) transmission lines on a 1 µm-thin Silicon Nitride membrane. The novelty of this membrane-based platform was bonding the transmitter and receiver directly on the transmission line to eliminate the radiation loss by the routine THz optics. Besides, the delicate thin-membrane dramatically reduces the dielectric loss of the platform which results in low-loss and low-dispersion THz-bandwidth pulses.In this paper, we introduce the design, theoretical model and the simulation results of a novel THz Apodized Bragg Grating (TABG) based on a periodic reflection of consecutive different impedance sections of CPS transmission lines on the membrane platform. This structure was introduced based on theoretical modelling and the simulation results. The CPS-TABG consists of 20 λ/2-length cascaded sections. The central frequency of the bandstop filter was selected around 0.8 THz to avoid signal distortion of the received terahertz pulse.

Enhancing directivity of terahertz photoconductive antennas using spoof surface plasmon structure

Terahertz photoconductive antenna (PCA) is an important device for generating ultrabroadband terahertz radiations, being applicable in various scenarios. However, the metallic electrodes in PCAs, a pair of coplanar strip lines (CSL), always produce horizontal electrode modes in a broad THz band, thus resulting in low directivity in the vertical direction. Here, we introduce spoof surface plasmon polariton (SSPP) structures to suppress horizontal electrode modes in a broad band. The suppression principles are accounted to both the forbidden band of the fundamental SSPP mode and the orthogonality between source and higher-order SSPP modes. In the SSPP-modified PCA, we achieve around 2 dBi higher directivity in the vertical direction compared to a typical CSL PCA. Unlike the narrow bands inheriting from conventional metamaterial resonators, the relative operational band of the SSPP-modified PCA is as broad as 48%. This planar SSPP structure is compatible with the well-developed micro fabrication technologies. Thus, our scheme can be combined with the semiconductor material engineering and plasmonic nanoscale structures for further increasing THz output power.