Effect of upper shielding and conductor backing on quasistatic parameters of asymmetric coplanar waveguides

CAD‐oriented analytic formulas are presented for calculating the quasistatic parameters of the conductor‐backed asymmetric coplanar waveguide (ACPW), the ACPW with upper shielding, and the conductor‐backed ACPW with upper shielding using conformal mapping techniques. The effect of the presence of the upper shielding and the conductor‐backing on the quasistatic TEM parameters is discussed. It is also presented that the expressions derived in this work can be used for calculating the quasistatic parameters of various symmetric and asymmetric CPWs. ©1999 John Wiley & Sons, Inc. Int J RF and Microwave CAE 9: 394–402, 1999     

Effect of finite and different ground‐plane widths on quasistatic parameters of asymmetrical coplanar waveguides

Fast, accurate, and simple closed‐form expressions are presented for calculating the quasistatic TEM parameters of asymmetrical coplanar waveguides (ACPWs) with finite and different ground planes. The effect of the ground‐plane width and the asymmetry in the ground‐plane widths and in the spacings of ACPWs on the line parameters is investigated by using the formulas derived by conformal mapping techniques. Comparisons are also made between the present results and the results available in the literature for both the conventional coplanar waveguide (CPW) and the ACPW. The results in this article are in very good agreement with the results derived by the conformal mapping technique, by the variational formulation, and by the spectral‐domain method. It has been shown that the asymmetry of both ground planes and spacings leads to a significant change of the quasi‐TEM parameters with respect to cases of the finite and infinite ground planes. © 2000 John Wiley & Sons, Inc. Int J RF and Microwave CAE 10: 383–389, 2000.     

Wideband 3‐dB broadside‐coupled CPW coupler with ACPW and DGS for directivity enhancement

Phase velocity compensation technologies using asymmetric coplanar waveguides (ACPW) with or without defected ground structures (DGS) are proposed to enhance the directivity of wideband 3‐dB broadside‐coupled coplanar waveguide (BC CPW) couplers. First, even‐ and odd‐mode analyses of BC CPW couplers with four shunt capacitors are performed to obtain closed‐form design formulas. Then, ACPW instead of the shunt capacitors are inserted to the input and output ports of the coupler to improve the directivity. Lastly, DGS combining with ACPW are applied to further improve the directivity and broaden the bandwidth. The measured results show that only using ACPW, the bandwidth for the directivity of better than 20 dB is 44.2% with a maximum directivity of 42.6 dB. When both ACPW and DGS are used, the bandwidth for the directivity of better than 20 dB is 63.3%, and that for the directivity of better than 30 dB is enhanced to 21.3% with a maximum directivity of 55.9 dB, which is more than 10 dB over the existing BC CPW couplers. © 2013 Wiley Periodicals, Inc. Int J RF and Microwave CAE 24:59–67, 2014.     

Analysis of line to line coupled coplanar waveguides with W‐shaped conductor backing using conformal mapping method

A W‐shaped microshield coupled parallel coplanar waveguide (CP CPW), which is a new type of CP CPW, is proposed. Closed‐form expressions are presented for calculating the quasistatic parameters of this coupled structure by using conformal mapping techniques. The effect of the W‐shaped conductor backing on the coupling between CPWs is also discussed. Comparisons are made between the present numerical results and the results available in the microwave literature for CPW V‐shaped microshield coupled lines (CWVMCLs) and CP CPWs with a flat conductor backing. In addition, the coupling coefficient of the coupled CPWs is shown to be significantly lower than that of the CWVMCLs in the literature. © 2002 Wiley Periodicals, Inc. Int J RF and Microwave CAE 12: 354–359, 2002. Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mmce10035     

Quasistatic analysis of cylindrical coplanar waveguide with multilayer dielectrics

CAD-oriented analytic formulas are given for calculating the quasistatic parameters of the cylindrical CPW with three dielectrics. The effects of the dielectric materials on the quasistatic characteristics are investigated by using conformal mapping techniques. The calculated results are compared with those obtained for a corresponding planar CPW and a cylindrical CPW with a single dielectric. The curvature effects on the quasistatic characteristics are discussed. Moreover, the present expressions can also be extended to the cylindrical CPW with multilayer dielectrics. © 1998 John Wiley & Sons, Inc. Int J RF and Microwave CAE 8: 303–314, 1998.     

Very accurate and simple CAD models based on neural networks for coplanar waveguide synthesis

Very accurate and simple neural models for coplanar waveguide (CPW) synthesis are proposed. The results obtained from these neural models are compared with the results of quasi‐static analysis, the other synthesis formulas, and other experimental works. The accuracy of the neural models is found to be better than 0.4% for 11,206 CPW samples. © 2005 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2005.     

A compact broadband coplanar waveguide fed circularly polarized printed monopole antenna with asymmetric modified ground plane

In this communication, a broadband circularly polarized (CP) monopole antenna with coplanar waveguide (CPW) feeding is proposed. It consists of a modified rectangular monopole, an asymmetric ground plane, a two‐linked inverted L‐shaped strips on the left CPW ground, and two rectangular horizontal slots in asymmetric CPW ground plane. The overall dimension is only 0.47λ _o × 0.47λ _o. The antenna prototype has been fabricated. The measured results indicate that a broad ?10 dB impedance bandwidth (IBW) of 107.5% (4.3 GHz, 1.85‐6.15 GHz) and a broad 3 dB axial ratio ARBW of 104.3% (4 GHz, 1.855‐5.9 GHz) can be achieved; the average realized gain is 2.3 dBi for the entire CP band. The proposed antenna is an attractive candidate for several wireless communication systems.     

CAD modeling of coplanar waveguide cross‐over air‐bridge

In this article, a new CAD model for the coplanar waveguide (CPW) cross‐over air‐bridge is proposed. The model takes into account the CPW open‐end capacitance and the vertical strips of the bridge. The section directly underneath the bridge is modeled as a small section of a microstrip line. Our results are in good agreement with the published full‐wave results. © 2005 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2005.     

A brief of recent research progress on ionospheric disturbances

Ionospheric disturbances are the main causes of space weather events, which seriously influence accurate navigation, telecommunication, and so on. It is a fundaznental issue to detect and analyze the dis- turbance processes of the ionosphere. Theoretically, the understanding of the mechanisms of most ionospheric disturbances depends on observational results. With the development of space observation techniques and re- lated equipments, various efforts have been made to analyze the long-term statistical variations as well as sudden disturbances of ionospheric observation results. We briefly report some research progresses of ionospheric dis- turbances achieved in recent years, with regard to ground-based and satellites observations. The purpose is to provide a reference about the latest research progresses and improve the development of the future ionospheric disturbances observations and related researches.     

A comparative study between shielded and open coplanar waveguide discontinuities

A comparative study between open and shielded coplanar waveguide (CPW) discontinuities is presented. In this study, the space domain integral equation method is used to characterize several discontinuities such as the open-end CPW and CPW series stubs. Two different geometries of CPW series stubs (straight and bent stubs) are compared with respect to resonant frequency and radiation loss. In addition, the encountered radiation loss due to different CPW shunt stubs is evaluated experimentally. The notion of forced radiation simulation is presented, and the results of such a simulation are compared to the actual radiation loss obtained rigorously. It is shown that such a simulation cannot give reliable results concerning radiation loss from printed circuits.     

叉指电容对铁电薄膜移相器相移影响的研究

文章采用准静态场法和分布参数电路模型分析计算了共面波导结构(CPW)铁电薄膜移相器的电容值与有效介电常数,通过对高频仿真软件HFSS的模拟结果与计算的不同结构电容值间的验证,发现电容值与有效介电常数表现出一种近似的线性关系。     

Compact CPW‐Fed slot antenna with harmonic suppression

A compact coplanar waveguide (CPW)‐fed uniplanar antenna with harmonic suppression characteristics is presented. The above characteristics are achieved by properly modifying the ground plane and adjusting the signal strip of an open‐ended CPW‐fed transmission line. The simulated and experimental characteristics of the antenna are presented, compared, and discussed. © 2011 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2011.     

A broadband coplanar waveguide to rectangular waveguide power divider using a slot

In this article, a broadband coplanar waveguide (CPW) to rectangular waveguide power divider using the dipole slot is proposed. The power divider consists of an input CPW port and two output rectangular waveguide ports. The CPW to rectangular waveguide power divider using the dipole slot has a return loss larger than 15 dB and an insertion loss equal to 3.08–3.27 dB in the whole X‐band (8.2–12.4 GHz). Furthermore, to broaden the bandwidth, the dipole slot is replaced by the bow‐tie slot. The CPW to rectangular waveguide power divider using the bow‐tie slot yields a return loss larger than 16 dB and an insertion loss equal to 3.05–3.29 dB from 8 to 13 GHz, which exceeds the X‐band. To verify our design, power dividers that use the dipole slot or the bow‐tie slot are fabricated and measured. The measurement results of both power dividers are in good agreement with the simulation results. © 2012 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2013.     

A MEMS reconfigurable DGS resonator for K-band applications

A MEMS reconfigurable defected-ground-structure (DGS) resonator using two-dimensional (2-D) periodic DGS for coplanar waveguide (CPW) transmission line and RF MEMS series-resistive switches is proposed. The introduced MEMS reconfigurable DGS resonator has approximately a fixed bandwidth of 8.1 GHz over a wideband frequency range (K-band). The proposed structure can be designed easily for other frequency bands by changing the number of unit-cells of the 2-D PDGS. A cascaded two parallel-resonance circuit model for the MEMS reconfigurable DGS resonator has been introduced as well. The equivalent circuit parameters extraction methods have also been derived. Simulations based on the proposed circuit model are in a very good agreement with the electromagnetic (EM) simulations, which suggests that the MEMS reconfigurable DGS resonator is an inductive controlled reconfigured structure. The structure is designed in CPW environment on a high-resistivity silicon substrate. It is therefore suitable for monolithic integration with standard IC process.     

A micro compact coplanar power divider at X-band with finite-width ground plane based on GaAs MMIC technology

A micro coplanar Wilkinson power divider at X-band on GaAs substrate is presented in this paper. The proposed power divider introduces a size reduction method, and the length of the transmission line is reduced to λ/8 (at 10 GHz). Since the two segments of the two edge coupled quarter-wave asymmetric coplanar striplines (ACPSs) with finite-width ground plane are closed to each other, their characteristic parameters, such as characteristic impedance and attenuation coefficient, are obtained using the quasi-static conformal mapping technique (CMT) of coupled coplanar waveguide (CCPW) with finite-width ground plane. S-parameters for the power divider are deduced in the case of quasi-static TEM even–odd mode. The fabrication process is compatible with the GaAs MMIC process. The measured S-parameters are compared with the simulated results of HFSS v.11 and the calculated results of TEM even–odd analysis. Simulated results show that it has reflection loss less of 16.5 dB and insertion loss less of 3.6 dB. Measured results show that the divider has reflection loss less of 15.0 dB and insertion loss less of 3.5 dB. Compared with conventional Wilkinson power divider, the length of the power divider is shortened from 2,620 to 1,570 μm.     

Accurate and simple synthesis formulas for coplanar waveguides

Simple and accurate closed‐form formulas obtained by using a differential evolution algorithm are presented for the synthesis of coplanar waveguides (CPW). The results of the synthesis formulas proposed in this article are compared with those of the quasi‐static analysis, the synthesis formulas reported by the other researchers and also the experimental works available in the literature. The accuracy of the proposed synthesis formulas is found to be better than 0.75% for 9256 CPWs samples. © 2008 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2008.     

CAD modeling of coplanar waveguide interdigital capacitor

A lumped‐element circuit is proposed to model a coplanar waveguide (CPW) interdigital capacitor (IDC). Closed‐form expressions suitable for CAD purposes are given for each element in the circuit. The obtained results for the series capacitance are in good agreement with those available in the literature. In addition, the scattering parameters obtained from the circuit model are compared with those obtained using the full‐wave method of moments (MoM) and good agreement is obtained. Moreover, a multilayer feed‐forward artificial neural network (ANN) is developed to model the capacitance of the CPW IDC. It is shown that the developed ANN has successfully learned the required task of evaluating the capacitance of the IDC. © 2005 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2005.     

UWB coplanar waveguide‐fed coplanar strips rectangular spiral antenna

This article proposes an ultra‐wideband coplanar strips (CPS) rectangular spiral antenna that is fed by coplanar waveguide (CPW). The CPS is formed by gradually reducing the width of the CPW ground planes without the need of a balun. The antenna operates in the frequency band (3.5‐10.6 GHz) and has miniaturized size of 50 × 40 × 0.508 mm on a Rogers RO4003C substrate. The CPS spiral is terminated with a 100 Ω chip resistor for matching. A parametric study was performed to choose the CPS spiral dimensions. A good agreement is found between simulations and measurements in the radiation pattern and the return loss which was found to be better than 10 dB over the band. The measured peak gain ranges between 1 and 4.7 dBi.     

Design and simulation of a novel bridge-like coplanar waveguide for microelectromechanical systems

In this paper, a kind of novel bridge-like coplanar waveguide has been designed and simulated at 10 GHz. Compared with conventional CPW, this design has lower attenuation and wider available characteristic impedance range. In addition, this design can avoid the interference among the adjacent components of RF MEMS devices.     

Miniaturized substrate integrated waveguide 5G LTCC bandpass filter exploiting capacitive loaded cavities

In this article, a compact bandpass filter with a pair of transmission zeros exploiting capacitive loaded cavities is presented. The proposed filter structure is mainly composed of coplanar waveguide (CPW) feeding structures and four substrate integrated waveguide (SIW) resonators. The size of the filter has been greatly reduced due to the capacitive loaded circle metallic septum and the vertical coupling of stacked cavities in three dimensional structures by low temperature co‐fired ceramic technology. The filter not only achieves the advantages of high‐selectivity, a much wider upper stopband bandwidth, but also realizes a miniaturized volume of 3.35 × 2.10 × 0.66 mm³. The simulated and measured results show the bandpass filter achieves a center frequency of 28 GHz with 3 dB fractional bandwidth of 8%. The filter is suitable for application in 5G wireless communication.