Finite Ground Coplanar Waveguide Research Articles

Characterization of Additively Manufactured Suspended Finite Ground CPW Interconnects Enhanced by Femtosecond Laser Micromachining

Characterization of Additively Manufactured Suspended Finite Ground CPW Interconnects Enhanced by Femtosecond Laser Micromachining

Versatility of Laser Enhanced Direct Print Additive Manufacturing

This paper provides examples of the use of direct print additive manufacturing to fabricate RF/microwave and optical components. Direct print additive manufacturing is the combination of extrusion and micro-dispensing on a single tool. The design, 3D printing process and material selections for finite ground coplanar waveguide (FG-CPW) planar transmission lines, the integration of DC contact RF MEMS switches within the FG-CPWs, and optical interconnects are detailed. Picosecondpulsed laser machining is performed to enhance the finish quality of the devices and achieve minimum feature size down to 6 μm specifically for the RF switch.

Characterization of Finite-Width Ground Coplanar Waveguides on High Resistivity Silicon With Ultralow Metallization Thickness

In this paper, we report the microwave properties of finite-ground coplanar waveguides (CPWs) fabricated on a thermally oxidized high resistivity silicon substrate. The ultralow metallization thickness indicates a gold metallization with a thickness in the range from 10 to 100 nm. We present measured magnitudes and phases of the $S_{11}$ and $S_{21}$ parameters of the CPW segments in the frequency range from 0.1 to 26 GHz, which are transformed based on the signal flow graph to the characteristic impedance $Z_{0}$ , the attenuation coefficient $\alpha $ , and the effective dielectric constant $\varepsilon _{\mathrm {eff}}$ . We analyze the CPW attenuation dependence on the metallization thickness based on the $\alpha (f) =\alpha _{0}\cdot (f/1~\text {GHz})^{n}$ model.

RF-MEMS-Based DPDT Switch on Silicon Substrate for Ku-Band Space-Borne Applications

A RF-MEMS (radio-frequency microelectromechanical-system) based DPDT (double pole double throw) switch for the Ku band has been designed and analyzed for this article. The switch topology is based on the FG-CPW (finite ground-coplanar waveguide) configuration of a microstrip-transmission line. An FEM-based multiphysics solver is used for the evaluation of the spring constant, stress distribution, and pull-in voltage regarding the requirements of the switch-beam unit. The electromagnetic performance of the switch is investigated for a <TEX>$675{\mu}m$</TEX> thick silicon substrate. For the operational frequency of 14.5 GHz, an insertion loss better than -0.3 dB, a return loss better than -40 dB, and input/output- and output-port isolations better than -35 dB are achieved for the switching unit.

Propagation Characteristics and Modeling of Meshed Ground Coplanar Waveguide

Additive manufacturing (AM) is increasingly being used for the realization of microwave circuits. In this method of fabrication, conductive patterns can be printed directly without the need of a mask or subtractive techniques such as etching a metalized substrate surface. For most AM processes, the materials used for the conductive layer are the most expensive ones; hence, there is value in minimizing the conductor surface area used in a circuit. In this paper, the approach of meshed ground coplanar waveguide (MGCPW) is analyzed by simulating, fabricating, and measuring a broad set of MG geometry sizes. Furthermore, a physical–mathematical model is presented, which predicts the characteristic impedance and the capacitance per unit length of MGCPW with less than 5.4% error compared with simulated data. A set of filters is designed and fabricated in order to demonstrate the approach. The main parameter affected by meshing the ground plane is the attenuation constant of the waveguide. It is shown that 50% mesh density in the ground plane of an MGCPW line can be used with less than 25% increase in the loss. In contrast, the loss of finite ground coplanar waveguide can increase by as much as 108% when the ground size is reduced by the same factor (50%). Both 3-D printing (microdispensing) and traditional printed circuit board manufacturing are used in this paper, and most of the propagation characterization is performed at 4 GHz.

밀리미터파 시스템용 초광대역 마이크로스트립-FGCPW 전이구조 설계

본 논문에서는 초광대역의 마이크로스트립-FGCPW 전이구조 설계를 제안하였다. 제안한 전이구조는 바닥면 그라운드의 변화를 통해 전계 및 임피던스 정합을 구현하였다. 등각 사상을 이용하여 전이구조를 해석하여 닫힌 형태의 수식을 제안하였으며, 제안한 수식은 상용 EM 시뮬레이터와 3.3 % 오차 범위의 정확성을 가짐을 확인하였다. 제작된 전이구조는 9~40 GHz 이상의 대역에서 1 dB 이하의 손실과 10 dB 이상의 반사손실을 가짐을 확인하였다. A new design for an ultra-wideband microstrip-to-FGCPW(Finite Ground Coplanar Waveguide) transition is presented. The proposed transition provides the electric field and impedance matching between adjacent transmission lines by ground shaping. The transition is designed on the analytical expressions of whole transitional structure. Conformal mapping is applied to obtain the characteristic impedance of FGCPW with bottom aperture within 3.3 % accuracy as compared with the EM-simulation results. As design example, the fabricated transition in back-to-back configuration provides insertion loss less than 1 dB per transition and return loss better than 10 dB for frequencies from 9 GHz to over 40 GHz.

A novel FGCPW-fed flag-shaped UWB monopole antenna

A finite-ground coplanar waveguide (FGCPW)-fed compact ultra-wideband flag-shaped monopole antenna is presented. The antenna consists of a FGCPW-fed monopole asymmetrically loaded with a rectangle strip. The antenna has a compact size of 21.85 × 28 × 1.6 mm3. Parametric analysis is conducted to understand the effect of various parameters on the antenna performance. Simple design equations are presented to provide reliable initial design of the antenna if a different substrate is to be used. Constant gain and monopole-like radiation patterns are observed along the entire operating range from 3.1 to 12 GHz. Investigation of the time domain characteristics reveals that the proposed antenna exhibits excellent pulse handling capabilities.

Propagation of Spin Waves Excited in a Permalloy Film by a Finite-Ground Coplanar Waveguide: A Combined Phase-Sensitive Micro-Focused Brillouin Light Scattering and Micromagnetic Study

The excitation of spin waves by a microwave current injected into a coplanar waveguide with finite-width ground lines on a continuous Permalloy film is investigated both experimentally and numerically. Phase sensitive micro-focused Brillouin light scattering has been employed to reveal the spatial profile of the propagating spin waves in the magnetostatic surface wave geometry. The experimental results have been satisfactorily reproduced by means of micromagnetic simulations. The exciting microwave field used in this simulation has the spatial profile defined by the coplanar waveguide and user-defined periodic boundary conditions were employed in order to simulate the extended system. The resulting space and time dependent evolution of the magnetization has been analyzed by means of one and two dimensional fast Fourier transform algorithm in order to obtain the spatial profile and the frequency spectrum of the excited spin waves as well as their dispersion relations. Evidence is given to asymmetric emission from the two sides of the coplanar waveguide due to the symmetry breaking related to the sense of precession of the dynamical magnetization, as well as to the near-field effects of the extended spin wave emitter.

A CPW-Fed Triangular Monopole Antenna with Staircase Ground for UWB Applications

In this paper, a monopole antenna with triangular shaped patch based on coplanar waveguide (CPW)-feed is presented. The proposed antenna comprises a planar triangular patch element with a staircase ground which offers ultra wide bandwidth. The impedance bandwidth can be tuned by changing staircase shaped ground parameters (number of steps, step length, and/or its width). The overall size of the antenna is 28mm×26mm×1.6mm including finite ground CPW feeding mechanism. The antenna operates in the frequency range from 3.2-12GHz covering FCC defined UWB band with more than 100% impedance bandwidth. Stable omni-directional radiation patterns in the desired frequency band have been obtained. Measured data fairly agree with the simulated results.

Experimental study of the effect of ground width for millimetre-wave multilayer coplanar waveguides in ceramic multichip module technology

This study presents the accurate characterisation and detailed experimental study of the effect of ground-plane width and suppression of higher-order parasitic modes extending the frequency of operation up to 110 GHz for multilayer conductor-backed coplanar waveguide lines, fabricated in cost-effective thick-film multichip module (MCM) technology. The coplanar waveguides (CPWs) and components have been realised on multiple layers of dielectric onto a ceramic substrate using straightforward and cost-effective photoimageable thick-film process, demonstrating a very low loss of &lt;0.2 dB/mm at 80 GHz for a finite ground CPW and extremely low loss of &lt;0.1 dB at 76 GHz for CPW layer transitions, which are better than many reported results for MCM technologies. Further, the effective dielectric constant (ɛeff) and characteristic impedance (Zch) are extracted from two-port S-parameters measured on a single-line and by conversion to ABCD parameters, to investigate the practical effect of ground-plane width on CPWs on a multilayer ceramic substrate and to facilitate realisation of a cost-effective millimetre-wave MCM.

Small Tri-Band Monopole Antenna for WiMAX/WLAN Applications

A small coplanar waveguide (CPW)-fed tri-band monopole antenna for the worldwide interoperability for microwave access (WiMAX) and wireless local area network (WLAN) applications is proposed. The antenna is simply composed of a T-shaped monopole, a L-shaped monopole and an inverted L-shaped stub extended from the ground. Experimental results show that the proposed antenna covers 2.5–2.71 GHz, 3.39–3.72 GHz and 5.14–5.87 GHz with 10 dB return loss, covering all the 2.5/3.5/5.5 GHz WiMAX bands and 5.2/5.8 GHz WLAN bands. Furthermore, the antenna has a simple planar structure and a small size of only 17.7 × 21.5 mm2, including the finite ground CPW feeding mechanism. Good dipole-like radiation characteristic is obtained over the operating bands.

Design of Compact Dual-Wideband Antenna With Assembled Monopoles

A coplanar waveguide (CPW)-fed dual-wideband antenna formed by a triangular monopole and a U-shaped monopole is presented. The antenna can generate two wide bands centered at about 2.5 GHz and 5 GHz to cover all the 2.4/5.2/5.8 GHz WLAN bands and the 2.5/3.5/5.5 WiMAX bands. Furthermore, the antenna has a simple planar structure and occupies a small size of about 28 X 33 mm2, including the finite ground CPW feeding mechanism. Good dipole-like radiation characteristics over the operating bands are obtained.

Compact dual‐wideband antenna for WLAN/WiMAX applications

AbstractA compact CPW‐fed dual‐wideband antenna formed by a rectangular ring monopole and a rectangular monopole is presented. The measured 10 dB bandwidths for return loss are achieved to be 46.3% (2.36–3.78 GHz) and 31.4% (5.1–7 GHz) in the lower and upper band, respectively, covering all the 2.4/5.2/5.8 GHz WLAN bands and the 2.5/3.5/5.5 GHz WiMAX bands. Further, the proposed antenna has a simple planar structure and occupies a small size of 28 × 36 mm2, including the finite ground CPW feeding mechanism. Good monopole‐like radiation characteristic are obtained over the operating bands. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 1228–1231, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25156

A Compact Dual-Band Planar Antenna for DCS-1900/PCS/PHS, WCDMA/IMT-2000, and WLAN Applications

A compact dual-band planar antenna developed for DCS-1900/PCS/PHS, WCDMA/IMT-2000, and WLAN applications is presented. The proposed antenna consists of a flared monopole with an additional sleeve for dual-band applications. The overall size of the antenna is 40 mm times 25 mm times 1.6 mm including the Finite Ground CPW feeding mechanism. The antenna operates in two frequency bands from 1.83 to 2.34 GHz and 3.23 to 5.76 GHz covering DCS-1900/PCS/PHS, WCDMA/IMT-2000, and WLAN bands. Simulation results along with measurements of the prototyped antenna are presented and discussed.

Improved circuit model for coplanar‐waveguide to microstrip‐line transition on silicon substrate

AbstractAn improved equivalent circuit model is proposed to accurately characterize a metal via transition, between a finite ground coplanar waveguide (FGCPW) and a finite ground thin film microstrip line (FGTFML), which was fabricated using standard CMOS technology. This circuit model with only a few lumped‐circuit elements is established and optimized to achieve a wide frequency range of operation, i.e., 1.0–30.0 GHz. A via transition circuit is fabricated and the measured results have evidently validated the predicted results derived from our proposed circuit model. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 141–144, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23011

Characteristics of coplanar waveguide on lithium niobate crystals as a microwave substrate

A finite ground coplanar waveguide (FG-CPW) on lithium niobate (LiNbO3) substrates, without a thin SiO2 buffer layer, was experimentally characterized by using on-wafer measurements. The dielectric constant and the characteristic impedance were extracted from calibrated measurements made at up to 20GHz using the FG-CPW method. The loss tangent was then obtained by the conformal mapping approach after the dielectric constant and characteristic impedance had been accurately extracted. The dielectric losses of LiNbO3 substrates are not negligible even in the X band.

Performance degradation of some on‐chip finite‐ground coplanar waveguide (FGCPW)‐built passive devices at high temperature

AbstractAt different temperatures, the performance degradation of on‐chip finite‐ground coplanar waveguides (FGCPWs) and FGCPW‐built meander‐line inductors are investigated in this article. These passive devices were all fabricated on a double‐layer polyimide and GaAs substrates and often used in monolithic microwave integrated circuits. It is shown that the increase in temperature causes the increase in series resistance or conductive loss of the metallization planes, and the temperature coefficient of series resistance depends on both frequency and metallization thickness. At given metal plane thickness and operating frequency, the conductive attenuation constant increases linearly with increasing temperature. Because of the increase in conductive loss, the maximum of Q‐factor of each meander‐line inductor decreases linearly with increasing temperature. While the temperature effect on the parasitic coupling between two parallel FGCPW stubs or between two neighboring inductors can be neglected, even the temperature reaches 438 K. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 1754–1759, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21751

Excitation of coupled slotline mode in finite-ground CPW with unequal ground-plane widths

The coupling between the desired coplanar-waveguide (CPW) mode and the unwanted coupled slotline mode is presented for finite-ground CPWs with unequal ground-plane widths. Measurements, quasi-static conformal mapping, and finite-difference time-domain analysis are performed to determine the dependence of the slotline-mode excitation on the physical dimensions of the finite-ground coplanar line and on the frequency range of operation. It is shown that the ratio of the slotline mode to the CPW mode can be as high as 10 dB. Air-bridges are shown to reduce the slotline mode by 15 dB immediately after the air-bridge, but the slotline mode fully reestablishes itself within 2000 mum of the air-bridge. Furthermore, these results are independent of frequency

Design of a 5.8-GHz rectenna incorporating a new patch antenna

This paper presents a rectifying antenna (rectenna) designed in a finite ground coplanar waveguide (FG-CPW) circuit. The new rectenna element is based on a new patch antenna and a new band-stop filter, in the form of compact CPW resonant cell (CCRC), located between the antenna and the rectifying diode. The novel coplanar patch antenna with about 9-dBi gain is proposed for the rectenna. The CCRC is adopted to suppress the second harmonic from radiation. With the use of this band-stop filter, a radio-frequency-to-direct-current (RF-to-dc) conversion efficiency of 68.5% using a 270-/spl Omega/ load resistor is obtained.

Average power-handling capability of the signal line in coplanar waveguides on polyimide and GaAs substrates including the irregular line edge shape effects

The average power-handling capability (APHC) of the signal line in finite-ground coplanar waveguides (FGCPWs) on polyimide and GaAs substrates is evaluated in this paper. In our approach, the ohmic loss of metal lines is characterized in different ways, and the effects of an irregular edge shape are also considered. The rise in temperature of the signal line is determined by single- and double-layer thermal models, with the temperature-dependent properties of the thermal conductivity of GaAs material treated appropriately. Parametric studies are carried out to investigate the overall effects of signal-line width, thickness, conductivity, edge-shape angle, and polyimide thickness on APHC. Some possible ways to enhance the APHC of these FGCPWs are also proposed. © 2005 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2005.