Coplanar Waveguide Line Research Articles

CPW‐fed multiband semifractal antenna for RFID reader applications

ABSTRACTA new design CPW‐fed printed semifractal antenna with arc‐line feed for RFID reader applications is presented. The proposed antenna comprised of a conjunction of coplanar waveguide and microstrip feed line, a semifractal patch, which is usable for RFID reader frequency bands. By embedding a semifractal patch, multiresonance characteristics at 3.8, 5.8, 8.2, and 9.7 GHz frequencies are obtained. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:1852–1853, 2015

Microwave properties of ferromagnetic nanowire arrays patterned with periodic and quasi-periodic structures

Microwave properties of ferromagnetic nanowire arrays patterned with periodic and quasi-periodic structures were investigated in this study. The periodic and quasi-periodic structures were designed based on Fibonacci sequence and golden ratio. Ni nanowires arrays were electrodeposited in anodic aluminum oxide (AAO) templates with patterned Cu electrodes, and then the AAO templates were attached to the coplanar waveguide lines fabricated on quartz substrate for measurement. The S21 of both periodic and quasi-periodic structure-patterned Ni nanowire arrays showed an extra absorption peak besides the absorption peak due to the ferromagnetic resonance of Ni nanowires. The frequency of the absorption peak caused by the patterned structure could be higher than 40 GHz when the length and arrangement of the structural units were modified. In addition, the frequency of the absorption peak due to the quasi-periodic structure was calculated based on a simple analytical model, and the calculated value was consistent with the measured one. The experimental data showed that it could be a feasible approach to tune the performance of microwave devices by patterning ferromagnetic nanowires.

Odd-mode surface plasmon polaritons supported by complementary plasmonic metamaterial.

Surface plasmon polaritons (SPPs), either on metal-dielectric interfaces in optical frequencies or on structured metal surfaces in the lower frequencies, are dominantly even modes. Here we discover dominant odd-mode SPPs on a complementary plasmonic metamaterial, which is constructed by complementary symmetric grooves. We show that the fundamental SPP mode on such a plasmonic metamaterial is a tightly confined odd mode, whose dispersion curve can be tuned by the shape of groove. According to the electric field distributions of odd-mode SPPs, we propose a high-efficiency transducer using asymmetric coplanar waveguide and slot line to excite the odd-mode SPPs. Numerical simulations and experimental results validate the high-efficiency excitation and excellent propagation performance of odd-mode SPPs on the complementary plasmonic waveguides in the microwave frequencies.

A hybrid integrated ultra-wideband/dual-band antenna with high isolation

In this paper, we propose a novel integrated ultra-wideband (UWB) monopole antenna with dual-band antenna. The antenna consists of planar rectangular with semi-elliptical base and a rectangular dielectric resonator antenna (DRA) with dual-band operation. Both of them are excited via coplanar waveguide (CPW) lines. The experimental measurements show that the planar monopole provides an impedance bandwidth between 2.44 and 11.9 GHz which largely covers the entire UWB spectrum, and the rectangular DRA operates at two bands; 5.3–6.2 and 8.5–9.4 GHz. Additionally, the proposed structure ensures low mutual coupling between the two ports (with S21 less than −20 dB in the whole operating frequency band). The measured and numerical results show a good agreement.

INTEGRATED FLEXIBLE UWB/NB ANTENNA CONFORMED ON A CYLINDRICAL SURFACE

In this paper, an ultra-wideband (UWB) conformal monopole antenna integrated with a narrow-band (NB) rectangular slot antenna is designed and fabricated. The proposed structure consists of a circular disc monopole antenna printed on a cylindrical surface and fed by a coplanar waveguide line (CPW). A rectangular slot antenna, excited by a microstrip line, is integrated in the front of the UWB antenna. The simulations are performed using the CST Microwave Studio software. To validate the proposed antenna concept, an experimental prototype is fabricated and measured. The measured results show that the monopole antenna covers an ultra wideband from 2GHz to 12GHz with S11 < −10 dB and provides a very good isolation with a transmission coefficient below −20 dB across the operating band. Compared to planar integrated antennas, the proposed conformed structure possesses an important wideband, which can be used in many wearable electronic applications and communication systems.

CPW-Fed Frequency-Reconfigurable Slot-Loop Antenna With a Tunable Matching Network Based on Ferroelectric Varactors

A frequency-reconfigurable slot-loop antenna with a tunable matching network (TMN) is designed, fabricated, and measured. The frequency-reconfigurable antenna is designed by loading ferroelectric (FE) varactors along a slot loop. The varactor-loaded slot-loop antenna is fed using a coplanar waveguide (CPW) line rather than a microstrip line to preserve the advantage of being uniplanar. However, because it is more difficult to achieve a good matching over wide bandwidth with a direct CPW feed, we propose to add a TMN. It is found that the TMN can be realized using a series varactor, which does not increase the size of the antenna. Measurement results show that by adjusting the bias of the FE varactors from 0 to 15 V, the operating frequency of the antenna can be tuned from 6.71 to 9.14 GHz, translating into a 30.6% frequency tuning range (FTR). At 6.71 GHz, the size of the slot loop is $0.056 {\lambda _0} \times 0.056{\lambda _0}$ . When biased at 15 V, the antenna gain is $ - $ 3.1 dBi. Over the entire FTR, the return loss is greater than 20 dB, demonstrating the effectiveness of the tunable matching technique.

Compact Dual-SRR-Loaded UWB Monopole Antenna With Dual Frequency and Wideband Notch Characteristics

This letter presents the design of a compact dual-split-ring-resonator (SRR)-loaded coplanar waveguide (CPW)- fed ultrawideband circular monopole antenna exhibiting dual frequency notch and wideband notch characteristics. The SRR pairs are inductively coupled to the radiator and loaded on the back side of the CPW line. Fabricated prototypes were measured and compared to simulations, and good agreement was obtained.

Low Loss, Wideband, and Compact CPW-Based Phase Shifter for Millimeter-Wave Applications

This paper proposes a compact, low-loss, and low cost phase shifter for millimeter-wave phased array systems. The basic idea is to modify the propagation mode of a coplanar waveguide (CPW) by placing a high dielectric constant (40 <; ε <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">r</sub> <; 170) slab on top of it. The phase shift is varied by changing the air gap between the CPW line and the dielectric slab. A piezoelectric transducer has been used to control this air gap precisely. For fast but accurate modeling of the proposed phase shifter, two methods one based on spectral domain analysis and the other based on the conformal mapping have been developed and verified with full wave simulations and measurements. A prototype structure with the operational frequency range from 20 to 40 GHz is presented. The maximum phase shift obtained for the electrically controlled version at 40 GHz is 103 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">°</sup> with loss variation of 0.2 dB. The total length is 2 mm.

Opto-Electronic Chip-on-Film Packaging Technology Using Low-CTE Fluorinated Polyimide Optical Waveguide Films

We have developed a new type of single-mode optical waveguide film with a low coefficient of thermal expansion (CTE). The low-CTE film was fabricated by sandwiching a fluorinated polyimide optical waveguide layer between low-CTE polyimide layers. Its CTE is less than one-tenth that of conventional polyimide optical waveguide films. We fabricated opto-electronic (OE) films with coplanar waveguide lines on the film surface using this low-CTE film. We confirmed that the film has good optical, electrical, and mechanical characteristics. This low-CTE OE film can be used to integrate optical and electrical devices on a film.

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.

Inline capacitive RF power sensor based on floating MEMS beam for GaAs MMIC applications

A 0.01–20 GHz inline capacitive radio frequency (RF) power sensor with a floating microelectromechanical system (MEMS) beam is proposed. It is based on sensing the capacitance change of the MEMS beam above the coplanar waveguide line due to the electrostatic force. In the design, anchors of the MEMS beam are floating for accurate capacitive detection and flexible for increasing the sensitivity, and an impedance matching technique is utilised to improve the microwave performance. The fabrication of this sensor is compatible with the GaAs monolithic microwave integrated circuits (MMICs) process. The measured reflection loss of the capacitive sensor is <−18 dB, whereas the insertion loss is better than −0.38 dB up to 20 GHz. Experiments show that approximate linear relationships between the measured capacitance change and the input RF power are obtained, and the resulting average sensitivities are 120.8, 76.7, 87.6 and 61.0 aF/mW at 5, 10, 15 and 20 GHz, respectively.

Analysis of slow‐wave propagation in coplanar transmission lines with inkjet printed multiwalled carbon nanotubes network

AbstractThis article investigates the propagation along coplanar waveguide (CPW) structures, where multiwalled carbon nanotubes (MWCNTs) network layers are deposited using inkjet printing. Electrical parameters are extracted from measured S‐parameters data over the frequency range from 10 MHz to 26.5 GHz. The results clearly demonstrate two distinct propagation modes. At low‐frequencies, a slow‐wave factor up to 7 is achieved. With increasing frequency, attenuation becomes significant, while the propagation constant tends to a linear TEM regime. An equivalent lumped element circuit for CPW structure with MWCNTs network is developed and describes well the measured behavior up to 26.5 GHz. Thanks to the extracted equivalent circuit, the origin of the observed slow‐wave phenomenon is confirmed: it is ascribed to a larger capacitance per unit length of the CPW line induced by the presence of the CNTs network that prevents/limits the expansion of fields into air. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:1118–1124, 2014

RF Performance of SOI CMOS Technology on Commercial 200-mm Enhanced Signal Integrity High Resistivity SOI Substrate

RF performance of a 200-mm commercial-enhanced signal integrity high resistivity silicon-on-insulator (eSI HR-SOI) substrate is investigated and compared with its counterpart HR-SOI wafer. By measuring coplanar waveguide lines and substrate crosstalk structures, it is demonstrated that losses are completely suppressed leading to virtually lossless linear substrate. Moreover, a reduction of the second harmonic distortion by more than 25 dB is measured on eSI HR-SOI wafer compared with HR-SOI. Excellent matching between experimental dc and RF characteristics of fully depleted SOI MOSFETs measured on top of HR-SOI and eSI HR-SOI is demonstrated. Furthermore, digital substrate noise is reduced by more than 25 dB on eSI HR-SOI compared with HR-SOI, when injected noise varies from 500 kHz to 50 MHz. The eSI HR-SOI substrate is fully compatible with the CMOS process and could be considered as a promising solution for the RF front-end-modules integration and system-on-chip applications.

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.

Fabrication and characterization of aluminum airbridges for superconducting microwave circuits

Superconducting microwave circuits based on coplanar waveguides (CPW) are susceptible to parasitic slotline modes which can lead to loss and decoherence. We motivate the use of superconducting airbridges as a reliable method for preventing the propagation of these modes. We describe the fabrication of these airbridges on superconducting resonators, which we use to measure the loss due to placing airbridges over CPW lines. We find that the additional loss at single photon levels is small, and decreases at higher drive powers.

Novel Dual-band Slot Antenna Design for Bluetooth and UWB Applications

A novel technique to introduce an additional low frequency band to compact ultra wideband (UWB) slot antennas is proposed in this paper. To get an additional Bluetooth band, a parasitic strip is mounted on the back side of the slot edge. Because of the interaction of the strip and the slot edge, the Bluetooth band can be obtained while a notch band between the Bluetooth band and UWB band also appears. Two types of feeding, coplanar waveguide and microstrip line, are investigated. The proposed antennas are both fabricated on a low-cost FR4 substrate and have compact size (24 mm × 28 mm × 1 mm). The good agreement between measured and simulated results verifies our design.

Manufacture of Radio Frequency Micromachined Switches with Annealing

The fabrication and characterization of a radio frequency (RF) micromachined switch with annealing were presented. The structure of the RF switch consists of a membrane, coplanar waveguide (CPW) lines, and eight springs. The RF switch is manufactured using the complementary metal oxide semiconductor (CMOS) process. The switch requires a post-process to release the membrane and springs. The post-process uses a wet etching to remove the sacrificial silicon dioxide layer, and to obtain the suspended structures of the switch. In order to improve the residual stress of the switch, an annealing process is applied to the switch, and the membrane obtains an excellent flatness. The finite element method (FEM) software CoventorWare is utilized to simulate the stress and displacement of the RF switch. Experimental results show that the RF switch has an insertion loss of 0.9 dB at 35 GHz and an isolation of 21 dB at 39 GHz. The actuation voltage of the switch is 14 V.

Monolithic Wafer-Level Rectangular Waveguide and Its Transition to Coplanar Waveguide Line Using a Simplified 3-D Fabrication Process

In this paper, we are introducing a new category of wafer-level micromachined rectangular waveguide devices and illustrate a new transition of these devices to Coplanar Waveguide (CPW) lines for millimeter-wave applications. The 3-D fabrication process used in this paper utilizes a combination of thin film and thick film processes and produces a simple three-mask fabrication process. As a result, all the on-wafer elements such as the waveguide, the CPW lines, and their transition are simultaneously fabricated, which eliminates the ever-existing requirement of hybrid assembly of the waveguide parts. A metalized post is employed to couple the signal from the CPW line to the waveguide. Unlike the previous designs that are mostly based on capacitive coupling, the proposed CPW to waveguide transition is based on inductive coupling, which simplifies the fabrication requirements and improves the performance. Here, the entire back-to-back structure is designed, fabricated, and measured on a 10 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> wafer area. A wide-band RF performance is measured for the proposed waveguide structure. Our measured results show an insertion loss of as low as 1 dB at 72 GHz range. The proposed technique to realize wafer-level waveguides has great potential to include a variety of waveguide topologies including bends and arcs. Besides, this method allows for further expansion of the topic to integrate MEMS components inside the waveguide.

Packaging a $W$-Band Integrated Module With an Optimized Flip-Chip Interconnect on an Organic Substrate

This paper, for the first time, presents successful integration of a W-band antenna with an organically flip-chip packaged silicon-germanium (SiGe) low-noise amplifier (LNA). The successful integration requires an optimized flip-chip interconnect. The interconnect performance was optimized by modeling and characterizing the flip-chip transition on a low-loss liquid crystal polymer organic substrate. When the loss of coplanar waveguide (CPW) lines is included, an insertion loss of 0.6 dB per flip-chip-interconnect is measured. If the loss of CPW lines is de-embedded, 0.25 dB of insertion loss is observed. This kind of low-loss flip-chip interconnect is essential for good performance of W-band modules. The module, which we present in this paper, consists of an end-fire Yagi-Uda antenna integrated with an SiGe BiCMOS LNA. The module is 3 mm × 1.9 mm and consumes only 19.2 mW of dc power. We present passive and active E- and H-plane radiation pattern measurements at 87, 90, and 94 GHz. Passive and active antennas both showed a 10-dB bandwidth of 10 GHz. The peak gain of passive and active antennas was 5.2 dBi at 90 GHz and 21.2 dBi at 93 GHz, respectively. The measurements match well with the simulated results.

Balanced Right/Left-Handed Coplanar Waveguide With Stub-Loaded Split-Ring Resonators

In this letter, a host coplanar waveguide (CPW) loaded with modified split-ring resonators (SRR) is presented. In recent publications, it has been demonstrated that the capacitive interaction between the host CPW line and the SRRs is the cause of a right-handed band, which degrades the selectivity of the response. Consequently, an open-ended microstrip stub connected to the rings is used to modify this interaction, and thus has an effective control of the rejection above the passband. Fortunately, these stubs only affect the frequency position of the right-handed band. As a result, it is quite straightforward to obtain balanced composite right/left-handed (CRLH) transmission lines with increased transmission bandwidth and improved rejection levels, which are the main drawbacks of traditional SRR-loaded CPW lines. Moreover, the response of the modified cell shows a pair of transmission zeros at both sides of the passband. Therefore, this new cell is a very interesting choice for designing balanced CRLH lines and is very attractive for filter applications.