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.     

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.     

Symmetric coplanar waveguide sensor loaded with interdigital capacitor for permittivity characterization

This article presents the developing of interdigital capacitor (IDC) based symmetric coplanar waveguide (CPW) sensor to characterize the complex permittivity of unknown dielectric sheets. The symmetric structure is realized by using two identical 3 dB CPW dividers where each branch is loaded with an IDC unit. The proposed method is designed using three, five, and seven fingers of the IDC unit, and the measurement sensitivity is analyzed accordingly. The permittivity of tested samples is extracted by the genetic algorithm. To validate the robust sensing performance of the proposed method, simulation and experimental tests are performed and analyzed, and the accuracy is compared with published values. The proposed method gives the maximum error of 3.42%. With the feature of high‐sensitivity, the proposed sensor can be used as an excellent candidate for determining the permittivity of materials in microwave frequencies.     

Design of coplanar waveguide elliptic low pass filters

This article proposes three design topologies of coplanar waveguide elliptic low pass filters. The design procedure is simple and explained in detail for the first topology. Numerical results are provided using the commercially available simulation softwares IE3D and HFSS to show the validity of the design with very good agreement. The proposed filters yield less than 0.1 dB attenuation in the passband (0–2 GHz), with a controllable slope of the transition between passband and stopband. The width of the rejection band is increased by simple filter cascading resulting in a passband to stopband ratio of up to 1:6. © 2009 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2009.     

Modeling of coplanar waveguide meander‐line inductors

A unique and simple method of modeling a coplanar waveguide meander‐line inductor is presented. Using only the lower frequency response of electrically smaller inductors, their higher frequency response is predicted. In addition, the responses of physically larger inductors can also be made using circuit models synthesized directly from the unit cell layout of the inductors. The modeling and prediction results for an ideal metal and lossless substrate is presented, together with comparisons made for various lossy parameters. © 2002 Wiley Periodicals, Inc. Int J RF and Microwave CAE 12, 520–529, 2002. Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mmce.10052     

CAD model of a gap in a coplanar waveguide

The partial capacitance approach and conformal mapping techniques are used to evaluate simple closed-form models for parallel and series capacitances of equivalent π-network of a symmetric gap in a CPW. Models are compared with experimental data and full wave analysis. They are useful for a wide range of CPW parameters and frequencies. © 1996 John Wiley & Sons, Inc.     

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.     

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.     

Design of coplanar waveguide multilayer square spiral inductors for monolithic microwave integrated circuits

A square indicator using multilayer coplanar waveguide transmission lines on a GaAs fabricated by using monolithic microwave integrated circuits (MMIC) technology is presented. The polyimide layer formation, curing and dry etching processes are used in an attempt to obtain high quality dielectric layers suitable for MMIC applications. The experimental fabrication progress provides two metal layers with two polyimide spacer dielectric layers. A brief overview of the electromagnetic design process is included. The performance of the proposed spiral inductor is investigated experimentally and with electromagnetic simulations (Sonnet em) up to 20 GHz using RF‐on‐water measurements. A very good agreement is achieved, despite the highly three‐dimensional nature of the structure. ©1999 John Wiley & Sons, Inc. Int J RF and Microwave CAE 9: 86–92, 1999     

Shielded edge-coupled coplanar waveguide structures: Modes and field configurations

In this article we present the dispersion characteristics as well as frequency-dependent field configuration and characteristic impedance for edge-coupled, shielded, coplanar waveguide structures. The structures studied include conductor-backed and suspended configurations. Phenomena such as mode conversion and dispersion of the dominant modes are explained. The characteristic impedance behavior is shown to be directly related to the phenomenon of mode conversion. The analysis uses the method of lines. © 1996 John Wiley & Sons, Inc.     

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.     

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.     

基于共平面波导的可调低通滤波器的设计和制作

介绍了一种使用多触点MEMS开关实现的新型可调微波MEMS低通滤波器,应用MEMS制作工艺在石英衬底上实现滤波器结构.滤波器基于慢波共平面波导周期性结构,具有尺寸小、插损低、可与单片微波集成电路工艺兼容等优点.滤波器截止频率的大小取决于MEMS开关的状态.实验结果表明,当MEMS开关受到激励时,低通滤波器的3-dB截止频率从12.5GHz转换至6.1GHz,带内纹波小于0.5dB,带外抑制大于40dB,开关的驱动电压在25V左右.     

A novel tailored coplanar waveguide circularly polarized antenna controlled by the gravity field

In this article, a tailored coplanar waveguide (CPW) circularly polarized (CP) antenna is designed, whose operating band can be adjusted in a large range by the gravity field through rotating the antenna vertically. Due to the fluidity of liquid metal mercury, which is packaged in the antenna's glass containers, when the antenna is rotated, mercury will lead to different metal resonant units in different directions under the influence of gravity. This antenna utilizes CPW whose metal reflective surface and the main radiating patch are on the same side of the dielectric substrate. The dielectric substrate is made of FR4, and the metal radiation patch and the metal reflective ground are made of copper. Two metal branches separated from the main radiation patch are connected to the main radiating patch by a glass container. To verify concept of the design, equivalent prototypes have been fabricated and measured. The measured results are roughly consistent with simulated results within a reasonable error range. The measured results show that when the antenna turns 90° counterclockwise along the x‐axis (state I), the 10‐dB return loss bandwidth is 13.5% (4.54~5.2 GHz), and the 3‐dB axial ratio (AR) bandwidth is 13.8% (4.5~5.17 GHz). When the antenna turns 90°clockwise along the x‐axis (state II), the 10‐dB return loss bandwidth is 23% (3.73~4.7 GHz), and the 3‐dB AR bandwidth is 23% (3.73~4.7 GHz) within the antenna operating range. In the cases of two different working states, the proposed antenna can effectively cover the 5G communication band.     

Modeling gap discontinuity in coplanar waveguide using quasistatic spectral domain method

An efficient computer technique based on the spectral domain method is presented to solve the problem of modeling coplanar gap discontinuity. Comparison with available published data is done to confirm the accuracy of the method. © 2000 John Wiley & Sons, Inc. Int J RF and Microwave CAE 10: 150–158, 2000.     

A microfluidic sensor in coplanar waveguide configuration for localized micrometric liquid spectroscopy in microwaves regime

Microsystem Technologies - In this work, we present a sensor suitable for performing the spectroscopy on a localized micrometric volume of a generic liquid, in the spectral range comprised between...     

Miniaturized multi‐frequency Wilkinson power dividers based on nonuniform coplanar waveguide

In this work, the design of miniaturized dual‐ and triple‐ frequency Wilkinson power dividers using nonuniform coplanar waveguides is presented. The miniaturized configurations are achieved by replacing the conventional uniform arms with their equivalent multi‐frequency nonuniform transmission lines. The nonuniform width variation is governed by a truncated Fourier series expansion with coefficients optimized to obtain the desired multi‐frequency operation. The optimization process is carried out through the analysis of the even/odd mode circuits. The proposed dividers are simulated, fabricated, and measured to validate the design methodology. Simulated and measured results agree very well, and show input/output ports return loss and isolation better than 14.4 dB and transmission parameters in the range of ?3 ± 2 dB at the design frequencies. Size reduction of 16.7% and 17.6% are achieved for the fabricated dual‐ and triple‐frequency dividers, respectively.     

Ultra‐wideband bandpass filter on coplanar waveguide: Proposal and implementation

In this paper, a novel ultra‐wideband (UWB: 3.1 ～ 10.6 GHz) bandpass filter on coplanar waveguide (CPW) is presented, designed and implemented. At first, an open‐ended nonuniform or multiple‐mode resonator with three distinctive sections is constructed and investigated toward generating the first three resonant modes occurring around the lower‐end, center, and higher‐end of the UWB band. Then, a CPW interdigital capacitor element with enlarged ground‐to‐ground distance is characterized to excite two additional resonant poles below and above the UWB's center. As a result, a five‐pole UWB bandpass filter with only one full‐wavelength is constituted. Its performance is studied on the basis of a simple cascaded transmission‐line network, whose parameters are extracted from our self‐calibrated method of moments. After the optimized results are confirmed by full‐wave simulation over the filter layout, a UWB filter sample is fabricated to demonstrate the actual UWB passband behavior with the 2.8–10.2 GHz bandwidth, where the insertion loss is less than 1.5 dB and variation in group delay is less than 0.33 ns. © 2007 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2007.     

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.