Grounded Coplanar Waveguide Research Articles

Analytical and Experimental Investigation of Substrate Permittivity and Loss up to 67 GHz

In this paper, we characterize the substrate permittivity and overall loss of different planar transmission lines (TL) such as microstrip (MS), coplanar waveguide (CPW) and grounded CPW (GCPW) using on-wafer probes and a thru-reflect-line (TRL) calibration technique. The theory for calculation of the related effective permittivity from S-Parameter measurements is given and numerical simulations are being used for a fast and precise mapping of the effective permittivity to the physical value of the TL's substrate. The method presented can be used for higher frequencies, as long as single mode operation of the TLs is ensured. Thus, an overview on higher order modes in TLs and design rules to suppress them is given. The results up to 67 GHz for the aforementioned TL on a conventional RF substrate are presented and used to evaluate approximate models known from publications.

A Comparative Study between Via-Hole and Via-Free Grounded Coplanar Waveguide to Microstrip Transitions on Thin Polymer Substrate

A comparative study between via-holed and via-free back-to-back GCPW-MS-GCPW (Grounded Coplanar Waveguide-Microstrip lines) transitions is reported in this paper. According to simulation results, both via-holed and via-free transitions on commercial benzocyclobutene polymer 20 µm film show a bandwidth over 57 GHz. Bandwidth of optimized via-holed transitions increases with the via-hole diameter, up to 75 GHz with 300 μm via-hole diameter. The via-hole free transition achieves experimentally an ultrabroadband from 2 GHz to 78 GHz with an insertion loss of only 0.5 dB thanks to the copper metallization thickness of 2 μm. In addition, these measurement results are in perfect agreement with the simulation results. These via-free and via-holes transitions are very useful and requested in component packaging, on-wafer measurements of microstrip based microwave integrated circuits, and also the interconnections in hybrid circuits including both microstrip and coplanar structures.

CIRCULAR POLARIZED TRANSPARENT ANTENNA FOR 5.8 GHZ WLAN APPLICATIONS

A novel design for a transparent circularly polarized circular slot antenna fed by a coplanarwaveguide (CPW) is presented in this paper. The circular polarization is achieved by introducing atapered split gap in the ring patch of the circular slot antenna in combination with unequal CPWground arms. The antenna is designed using AgHT-4 laminated on a 2 mm thick glass with a relativepermittivity of 7. The proposed antenna is designed to operate at 5.8 GHz for WLAN applications. Thetapered split gap and inequality in the lengths of the CPW ground arms contribute to a 3 dB axial ratiobandwidth from 5.4 to 6.2 GHz. The proposed antenna has been studied theoretically and fabricated.The measured results show that the proposed antenna has a gain of 0.92 dB at 5.8 GHz. Reflectioncoefficient (S11), axial ratio (AR), and radiation patterns are presented and briefly discussed.

Small size tripleband monopole antenna with a parasitic element

ABSTRACTA small size (20 × 38.5 × 0.8 mm3) coplanar waveguide (CPW)‐fed monopole antenna for wireless local area network and worldwide interoperability for microwave access applications is proposed. To achieve tripleband operation, the proposed monopole antenna is designed with a modified symmetrical U‐shaped printed structure attached with a parasitic element behind it. Good impedance matching is also attained by loading two dissimilar notches separately into the two CPW ground planes. The measured 10‐dB impedance bandwidths of the three operating bands (fL, fM, and fH) are 16.96% (2.105–2.495 GHz), 28.72% (3.22–4.30 GHz), and 23.32% (4.895–6.125 GHz), respectively, and all bands of interest have yielded peak gain and radiation efficiency of more than 2.7 dBi and 65%. Detail process of designing the proposed antenna is explicitly shown, and vital parametric studies were also conducted by simulation. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:342–348, 2015

Easy installation CPW-fed technique for fan-beam array antenna using grounded reflector for wireless applications

A fan-beam linear array antenna employing a non-parasitic grounded reflector, a new Coplanar Waveguide (CPW)-fed network, and Grounded Coplanar Waveguide (GCPW) radiation elements is presented. This fan-beam antenna is achieved using a four-element conventional non-planar monopole integrated with CPW line, which is perpendicularly connected to CPW feed network. In addition, the grounded reflector is vertically connected to the ground part of CPW feed network. These three main parts together produce a fan-beam antenna that can satisfy beneficial input impedance, radiation patterns, and gain bandwidth requirements in the frequency range 3.2–3.66 GHz. This array covers applications of 3.3 and 3.5 GHz WiMAX (Worldwide Interoperability for Microwave Access) operating bands. Also, combining a non-planar GCPW monopole antenna as an array with a non-parasitic grounded reflector and CPW feed network provides designers with an advantageous fan-beam pattern to be generated. In addition, the reflector height is reduced to half by the concept of image theory. As a consequence, the spatial dimension of the antenna will be reduced. Therefore, this combination results in a cheap, lightweight, and easy installing non-planar printed array antenna at high frequency bands. Comparisons are made between results obtained with and without a reflector array antenna.

Composite right/left‐handed dual‐band metamaterial antenna with improved gain and efficiency

ABSTRACTIn this article, a duals‐band metamaterial antenna with a new composite right/left‐handed (CRLH) unit cell configuration is proposed. The antenna is a coplanar waveguide (CPW) base which uses quarter wave resonators without via. Both sides of the CPW ground plane are short circuited to the CRLH‐transmission line. The dimension is 31 mm × 22 mm × 1.52 mm, with electrical size of 0.23 λo × 0.17 λo × 0.011 λo at 2.26 GHz, and which is compact in size. Resonance frequency of the negative mode can be altered by controlling the loop currents. Peak gains of 1.74 and 2.69 dBi are obtained at 2.26 and 2.89 GHz. Radiation efficiencies of 64% and 92% are obtained at 2.26 and 2.89 GHz, respectively. The simulated and measured return losses, as well as the radiation patterns, are presented and compared. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:1575–1579, 2014

Two-Dimensional Scanning Antenna Array Driven by Integrated Waveguide Phase Shifter

A Butler matrix-fed two-dimensional (2-D) scan linearly polarized 2 × 2 microstrip ring antenna array (MRAA) is proposed and validated in low-cost substrate integrated waveguide (SIW) technology for Ka-band applications. The highly efficient, compact, and passive beam forming network (BFN) consists of SIW cruciform couplers as coupling unit, and its special topology is well adapted for feeding planar arrays. The wideband and high radiation efficiency antenna elements are aperture-coupled through slots etched on the top of a high permittivity SIW feed substrate. Such four antenna elements are used to construct 2 × 2 MRAA and to form four fixed beams, one in each quadrant at an elevation angle of 20 ° from the broad side array axis. A triangular grid arrangement is chosen to avoid grating lobes in the visible space. A 50- Ω grounded coplanar waveguide (GCPW) to SIW transition is used to avoid spurious input feed radiation loss. The array is measured to exhibit 3-dB beam width of 30 ° in both of the orthogonal planes, radiation efficiency of 70% for each port, and stable radiation pattern bandwidth of 7.6% at 26.5 GHz. The physical size of the demonstrated 2 × 2 array is 2.86λo×2.86λo×0.22λo.

RF Transmission Properties of Graphene with Coplanar Waveguide Structure

In this paper, we present the RF transmission characteristics of graphene-based coplanar waveguide (CPW) lines with different structure dimensions, including widths of signal trace, widths of ground plane, and spacings between the CPW signal and ground lines. It has been demonstrated that the energy loss of graphene-based CPW in the RF transmission process can be decreased by tuning the CPW dimensions. To further reduce the energy loss, both high-quality graphene and good contact between metal and graphene are required.

243 GHz low-noise amplifier MMICs and modules based on metamorphic HEMT technology

Two compact H-band (220–325 GHz) low-noise millimeter-wave monolithic integrated circuit (MMIC) amplifiers have been developed, based on a grounded coplanar waveguide (GCPW) technology utilizing 50 and 35 nm metamorphic high electron mobility transistors (mHEMTs). For low-loss packaging of the circuits, a set of waveguide-to-microstrip transitions has been realized on 50-μm-thick GaAs substrates demonstrating an insertion loss of <0.5 dB at 243 GHz. By applying the 50 nm gate-length process, a four-stage cascode amplifier module achieved a small-signal gain of 30.6 dB at 243 GHz and more than 28 dB in the bandwidth from 218 to 280 GHz. A second amplifier module, based on the 35-nm mHEMT technology, demonstrated a considerably improved gain of 34.6 dB at 243 GHz and more than 32 dB between 210 and 280 GHz. At the operating frequency, the two broadband low-noise amplifier modules achieved a room temperature noise figure of 5.6 dB (50 nm) and 5.0 dB (35 nm), respectively.

Hybrid SIW-GCPW Cruciform Directional Coupler

A novel hybrid SIW-GCPW cruciform coupler is proposed and demonstrated. This coupler consists of a cross-over of substrate integrated waveguide (SIW) and ground coplanar waveguide (GCPW) in a square junction. Efficient coupling is achieved by adding two inductive metallic posts on the diagonal line of the junction. Taking advantages of low profile, low insertion loss of SIW and flexibility of GCPW, this coupler structure can be integrated in microwave and millimetre-wave planar circuits, especially in beam-forming networks. A 3 dB coupler is designed and fabricated operating around 33 GHz. Characteristics of 15 dB isolation between the input port and isolated port are achieved over 18% bandwidth. Design considerations and simulated as well as measured results are presented and discussed.

Low-Profile Pattern-Reconfigurable Antenna with Vertical and Horizontal Shorting Lines in Grounded CPW Technology

A novel low-profile reconfigurable antenna is proposed for changing radiation patterns. The antenna is constructed on a circular patch fed by a grounded coplanar waveguide (GCPW). The circular patch has three vertical shorting lines and one horizontal shorting line. A p-i-n diode switch on the horizontal shorting line is used to configure the radiation pattern of the antenna. In the off state, the maximum radiation intensity occurs at <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$\pm 45^\circ$</tex></formula> to the circular patch. In the on state, the maximum radiation intensity occurs perpendicular to the circular patch. Simulation and measurement results at 2.3 GHz validate the reconfigurability of the proposed design.

A Linear Phase Filter in Quadruplet Topology With Frequency-Dependent Couplings

This letter presents a design of a linear phase microwave bandpass filter. The filter is composed of four resonators arranged in the quadruplet topology. Making the cross and one direct coupling dispersive gives additional design flexibility. The first advantage of using frequency-dependent couplings is the possibility to chose an arbitrary location of a pair of complex transmission zeros (TZs) in the s-domain. The second one is the presence of an additional imaginary transmission zero that improves the filter selectivity. We provide a proof-of-concept design of a filter using substrate integrated waveguide (SIW) technology. The frequency-dependent couplings are implemented in SIW as a composition of both: an inductive part realized in a form of an H-plane iris and a capacitive part realized as a grounded coplanar waveguide (GCPW). The measured filter characteristics prove the validity of the model.

60 GHz grounded‐coplanar‐waveguide‐to‐substrate‐integrated‐waveguide transition for RoF transmitters

A novel transition from a grounded-coplanar waveguide to a substrate integrated-waveguide (SIW) is presented featuring a fully planar bias tee for the development of 60 GHz radio-over-fibre photonic transmitters for indoor applications. The transition is intended to serve as a connection between a 60 GHz photodiode chip and SIW antennas suitable for indoor data distribution. Simulations show that in the whole 57-64 GHz communication band, the return loss (RL) is at least 15 dB, whereas the insertion loss (IL), is 12 dB.

A forward narrow-wall double-slot 3 dB coupler based on hybrid HSIW/GCPW guided-wave structure

Based on a novel hybrid guided-wave structure of half-mode substrate integrated waveguide (HSIW) and ground coplanar waveguide (GCPW), a forward narrow-wall double-slot 3 dB coupler with the center operating frequency of 18 GHz is proposed. The narrow-wall double-slot coupling mechanism between TE10 mode of SIW and TEM mode of GCPW is studied and efficient coupling is achieved by using triangle-shaped slots. Such coupler takes the advantages of low profile, low insertion loss of HSIW and flexibility of GCPW. The coupler is fabricated and the measured results are in agreement with the simulated ones. A relative bandwidth over 20% is achieved with 0.5 dB amplitude imbalance excited at different ports.

Loss Performance of Planar Interconnects on FR-4 Up to 67 GHz

This paper shows the performance of planar transmission lines (TLs) on a multilayer stack-up with a flame resistant-4 (FR-4)-based core up to 67 GHz. These lines will be used as interconnects to integrate a CMOS circuit with an antenna fabricated on FR-4 for a low-cost system-in-package solution. The attenuation characteristics of coplanar waveguide (CPW), grounded coplanar waveguide (GCPW), and microstrip lines with different configurations are investigated. The peak attenuation varies from 0.15 to 0.45 dB/mm at 60 GHz, depending on the line type and geometry. In addition, the effective permittivity and loss tangent of the multilayer stack-up are determined using CPW TLs. The overall results show that FR-4-based materials are viable candidates for packaging at the millimeter-wave frequency range if suitable line lengths are utilized.

Modeling and parameter extraction of CMOS on-chip coplanar waveguides up to 67 GHz for mm-wave applications

Coplanar waveguides (CPW) are widely used in mm-wave circuits designs for their good performance. A novel unified model of various on chip CPWs for mm-wave application, together with corresponding direct parameter extraction methodologies, are proposed and investigated, where standard CPW, grounded CPW (GCPW) and CPW with slotted shield (SCPW) are included. Several kinds of influences of different structures are analyzed and considered into the model to explain the frequency-dependent per-unit-length L, C, R, and G parameters, among which the electromagnetic coupling for CPWs with large lower ground or shield is described by a new C–L–R series path in the parallel branch. The direct extraction procedures are established, which can ensure both accuracy and simplicity compared with other reported methods. Different CPWs are fabricated and measured on 90-nm CMOS processes with Short-Open-Load-Through (SOLT) de-embedding techniques. Excellent agreement between the model and the measured data for different CPWs is achieved up to 67 GHz.

Design of a K Band MEMS Switch with CPW Defected Ground Structure

This paper presents a K band (18GHz-26.5GHz) shunt capacitive micro-electromechanical systems (MEMS) switch. This switch used the coplanar waveguide (CPW) Defected ground structure (DGS) which is made by etching defect structure in CPW ground line. Furthermore the beam structure of the proposed switch is composed of one girder and two supporting beams. The design of the switchs structure is benefit to the apart between the DC signal and AC signal. The simulated values of the isolation of the switch on off-states is-55 dB at18.9 GHz, and the return loss at K band is greater than-0.3 dB. The pull-in voltage of the switch is 13.3 V.

Modeling, Simulation and Implementation of Low Cost Calibration Method for Active Devices

Complete characterization of active devices has been done using accurate low cost two-port calibration method, SOLT, with vector network analyzer (VNA) using the 12-term error model. Generic SOLT test fixtures short, open, load and thru have been designed, simulated and built using grounded coplanar waveguide (GCPW) structure. The test fixtures have been first simulated for design verification and accuracy, and then built, measured and then their fixturing effects have been removed using the 12-term error model with VNA, HP8753ES. Several biasing schemes for the active devices have been simulated, implemented and measured. Results have been compared with the published manufacturer data and close agreement has been seen on all of them. It has been shown that the complete characterization of active devices using SOLT calibration method is possible when test fixtures are implemented using GCPW structure and simulated with planar electromagnetic simulators to increase the accuracy of the characterization parameters. Furthermore, this method helps identifying the best operating conditions of the device under test (DUT) for high performance.

Hybrid SIW-GCPW Narrow-Wall 3 dB Coupler

In this paper, a novel narrow-wall double-slot 3 dB coupler is proposed. Efficient coupling is achieved between a substrate integrated waveguide (SIW) and a ground coplanar waveguide (GCPW). Such hybrid integrated coupler combines the low-loss property of SIW with the flexibility of CPW. The coupling mechanism between TE10 mode of SIW and TEM mode of GCPW is studied. According to the provided theory, a 3 dB coupler is designed and fabricated operating around 18 GHz and achieves a relative bandwidth of 10%. The measured results are in agreement with the simulated ones.

60-GHz Circularly Polarized U-Slot Patch Antenna Array on LTCC

This communication presents a 60-GHz wideband circularly polarized (CP) U-slot patch antenna array of 4 × 4 elements on low temperature cofired ceramic (LTCC). A CP U-slot patch antenna is used as the array element to enhance the impedance bandwidth and a stripline sequential rotation feeding scheme is applied to achieve wide axial ratio (AR) bandwidth. Meanwhile, a grounded coplanar waveguide (GCPW) to stripline transition is designed for probe station measurement. The fabricated antenna array has a dimension of 14 ×16 × 1.1 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> . The simulated and measured impedance bandwidths, AR bandwidths, and radiation patterns are investigated and compared. Measured results show that the proposed antenna array has a wide impedance bandwidth from 50.5 GHz to 67 GHz for |S <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub> | <; -10 dB, and a wide AR bandwidth from 54 GHz to 65.5 GHz for AR <; 3 dB. In addition, it exhibits a peak gain of 16 dBi and a beam-shaped pattern with 3-dB beam width of 20 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">°</sup> . Moreover, its AR keeps below 3 dB within the 3-dB beam width.