Conductor-backed Coplanar Waveguide Research Articles

Broadband magneto-dielectric response of particulate ferrite polymer composite at microwave frequencies

Complex permittivity and permeability of a magneto-dielectric composite material is studied using shielded, conductor-backed coplanar waveguide technique over X-band. The propagation constant over the test frequency range is evaluated using element-to-element correspondence of the ABCD matrix computed from scalar scattering parameters without modifying the coplanar structure. The mathematical formulation is verified by performing permittivity and permeability measurements for air over the range 9.5–12.045GHz. Nano-sized nickel ferrite particles was synthesized using co-precipitation technique at different sintering temperatures. Average crystallite diameter is found to be 6.63–17.55nm. The composite with 2% and 4% volume fractions is fabricated by reinforcing 6.63nm ferrite particles in low density polyethylene matrix. The complex permittivity and permeability of the composite obtained from this method are also verified with cavity perturbation technique. The composite shows low saturation magnetization of 1.8745emu/g and reduced hysteresis loss at room temperature.

A Broadband 3 dB Coplanar Waveguides Directional Coupler with Conductor-backed Asymmetric Coplanar Waveguides Compensation

A novel broadband 3 dB directional coupler using broadside-coupled coplanar waveguides and conductor-backed asymmetric coplanar waveguides (ACPW) is proposed. To broaden the bandwidth (isolation more than 20 dB), a conductor-backed ACPW is inserted to each port of the proposed coupler as the parallel compensation capacitance. The proposed coupler can be easily realized on a single-layer substrate by using general PCB processes. The proposed coupler exhibits good impedance match , high isolation , balanced power distribution (3.2±0.4 dB), and consistent 90° (±0.6°) output ports phase difference across a significantly broad bandwidth of 50.6%, from 1.04 to 1.80 GHz. Simulation results are compared with the measurements, and a good agreement is observed.

A Broadband Transition Design for a Conductor-Backed Coplanar Waveguide and a Broadside Coupled Stripline

A broadband transition design between broadside coupled stripline (BCS) and conductor-backed coplanar waveguide (CBCPW) is proposed and studied. The E-field of CBCPW is designed to be gradually changed to that of BCS via a simple linear tapered structure. Two back-to-back transitions are simulated, fabricated and measured. It is reported that maximum insertion loss of 2.3 dB, return loss of higher than 10 dB and group delay flatness of about 0.14 ns are obtained from 50 MHz to 20 GHz.

A wideband electro-optic modulator based on long range surface plasmon resonances

A wideband electro-optic (EO) modulator based on long range surface plasmon resonancesis proposed and numerically demonstrated. The modulator model consists of aprism–dielectric–metal–EO polymer–metal structure, using attenuated total internalreflection to excite long range surface plasmon resonances and a conductor-backed coplanarwaveguide to distribute radiofrequency (RF) electrical signals. The parameters of thestructure are optimized and the results show that the different frequency signals withvoltages of 1.36 V at 6 GHz, 2.03 V at 20 GHz and 2.71 V at 60 GHz are enough to achieve amodulation index of 15.2%. The maximal modulation index can reach 76% ranging fromDC to 60 GHz by increasing the input RF voltage, and the insertion loss can bedecreased to 4.2 dB by adjusting the operating bias. High modulation efficiency, wideoperating bandwidth and low insertion loss are realized simultaneously in this design.

Leakage-Reduced Conductor-Backed Coplanar Waveguide With Periodic Structures and its Antenna Application

A simple method is described where the need of via holes is not required to suppress the inherent leakage of a conductor-backed coplanar waveguide (CBCPW). Pairs of slots are periodically etched on the side ground planes in close proximity to the central signal line. When one period of the structure is considered as a coupled-line section, it provides an open-open boundary condition leading to the all-pass frequency response. To further reduce the possible mode conversion caused by the impedance discontinuity, pairs of small patches are loaded inside the slots. Since the self-resonant frequency of the small patches is far beyond the frequency of interest, the impedance seen from the signal line to the small patches is relatively high suppressing the leakage. The proposed leakage-reduced CBCPW transmission lines both possess good insertion/return loss responses, low loss factor, and flat group delay characteristics. The operation frequency range of the proposed structures is up to 45 GHz. Both structures are then integrated with the coplanar patch antenna. It is demonstrated that using the proposed structures as feed lines could not only improve the antenna efficiency but also lower the cross polarization levels of the coplanar patch antenna, which operates at 5.5 GHz. More importantly, the proposed via-free structures would be more suitable for use in microwave and millimeter wave integrated circuits.

Capacitance of a conductor-backed coplanar waveguide with an upper shielding

In this letter, the capacitance of a conductor-backed coplanar waveguide (CPW) with an upper shielding is investigated.An electrostatic boundary-value problem of the conductor-backed CPW with an upper shielding is solved using the Fourier transform, mode matching technique, and superposition. The capacitance of the conductor-backed CPW is represented in a series and calculated in terms of the CPW geometry. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:1364–1368, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26007

스마트 그리드용 초광대역 저항성 전력 분배기

This article presents an ultra broadband resistive power divider circuit for smart grid applications. Since the future smart grid system is expected to deploy high speed power line communication, the frequency response of the resitive power divider circuit is naturally of significance. Employing a thin film technology, the resistive power divider was designed, measured, and fabricated. For the circuit design, the conductor-backed coplanar waveguide line was firstly designed and measured. The 3 dB cutoff frequency was 72 GHz and S11 remains <-20 dB upto 70 GHz. The fabricated resistive power divider shows the 3 dB cutoff frequency of 50 GHz. It was experimentally verified that the resistive power divider circuit shows the insertion loss of 6 dB for high-speed input signal (40 Gb/s).

A Novel Broadband CB-CPW to Microstrip Transition for Concept of Implementation in RF-Circuits

A novel design of conductor backed CPW (CB-CPW) to microstrip line transition is introduced. The uniqueness of this design is that the ground plane of the bottom layer is complete, so the design overcomes the problems of the ground-shaped similar structures. Besides, wide bandwidth of the proposed transition (1-dB BW is 200%) is drastically noticeable. No micromachining technique is used during the design procedure of this structure, resulting in low cost and easy fabrication. Both the simple and the back to back structures for the transition are presented. Also a novel optimization technique for the design of a tapered region of the transition structure is demonstrated. Simulation and measurement results are presented in this paper in order to validate the proposed concept.

Low-Cost High Gain Planar Antenna Array for 60-GHz Band Applications

An effective development of a class of low-cost planar antenna arrays having a high reproducibility is presented for 60-GHz band system applications. The proposed antenna arrays, based on the substrate integrated waveguide (SIW) scheme, consists of one compact SIW 12-way power divider and 12 radiating SIWs each supporting 12 radiating slots. A 50-¿ conductor-backed coplanar waveguide (CBCPW) integrated with CBCPW-to-SIW transition is directly used as the input of the antenna array, thus allowing to accommodate other circuits or MMICs at a minimum cost. An antenna array prototype was implemented on Rogers RT/Duroid 6002 substrate with thickness of 20 mils by our standard PCB process. Measured gain is about 22 dBi with a side lobe suppression of 25 dB in the H-plane and 15 dB in the E-Plane while the bandwidth for the 10-dB return loss is 2.5 GHz.

60–110 GHz low loss HDI transitions for LCP-packaged silicon substrate

Wideband 3D transitions from 60 to 110 GHz using 50 µm via technology on liquid crystal polymer (LCP) are presented. A conductor backed coplanar waveguide (CBCPW) transition on a homogeneous LCP sample shows less than 0.8 dB loss from 60 to 110 GHz. In addition, a CBCPW-to-CBCPW and a CBCPW-to-CPW transition on LCP bonded to silicon substrate are presented also in the range 60–110 GHz. The CBCPW-to-CBCPW transition shows less than 0.5 dB loss up to 100 GHz. The CBCPW-to-CPW transition yields less than 1 dB loss up to 110 GHz. These transitions are the first characterisation of vias in organic substrate packaged silicon in the 60–110 GHz frequency range.

Active Heatsink Antenna for Radio-Frequency Transmitter

This paper deals with the design of an active heat-sink antenna for radio-frequency transmitter. The antenna achieves electromagnetic and thermal functions by offering a suitable radiating pattern for transmission as high efficiency to remove the dissipated power within the transmitter by heat exchange to the surrounding medium. A test transmitter has been performed by combining a 2 GHz MESFET power amplifier in a conductor-backed coplanar wave-guide with a wire-fed patch heat-sink antenna connected to the ground plane. The active heat-sink antenna has been investigated by measurement and simulation. As expected, it was found that the antenna exhibits desirable electromagnetic performance as achieving an efficient thermal control by offering suitable operating temperature. A heat spreader connecting the transistor to the antenna, was especially developed to cause any significant influence on transmitter performance. The amplifier can deliver an output power as high as 5 W under natural convection with air at room temperature and atmospheric pressure. According to the temperature and direction of the antenna, thermal resistance of the transmitter was found between 6 and 8 K.W <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> . The transmitter can thus operate over a wide temperature range without any additional cooling device.

Capacitance of Asymmetric Conductor-Backed Coplanar Waveguides

Capacitance of asymmetric conductor-backed coplanar waveguides (CPWs) is studied. An electrostatic boundary-value problem associated with the asymmetric conductor-backed CPWs is solved based on the Fourier transform, mode matching technique, and superposition. The formulation for the capacitance of the asymmetric conductor-backed CPWs is obtained in a series form. The computation is performed to show the behaviors of the capacitance in terms of the CPW geometry.

Empirical Dispersion Formula of the Conductor-Backed Coplanar Waveguide with Via Holes

An empirical dispersion formula is proposed and experimentally verified considering higher order modes of the conductor-backed coplanar waveguide with via holes. For this purpose, an effective dielectric constant is extracted up to 100GHz from measured S-parameters. By fitting the extracted data, an empirical equation is extracted. The simulation of the Gaussian pulse transmission and the comparison results with the modeling data validate the reported expression.

Electromagnetic modelling of conductor-backed CPW based RF MEMS capacitive shunt switch

This article will detail the creation of an electromagnetic model of an RF MEMS capacitive shunt switch using the conductor-backed CPW configuration. Full-wave S-parameter analysis has been carried out to extract the S-parameter of the switches for different variants. The modelling also covers the effect of the tapering of the RF signal line as well as the permittivity variation on the switch parameters. Further, the ground metallisation effect because of the CB-CPW configuration on the switch parameters has been modelled and compared with the standard topology. A scalable lumped circuit model for the proposed topology has been generated which can be easily incorporated in the circuit simulator. The topology demonstrated can achieve frequency downscaling without increasing the size and complexity of the circuit. Comparison of modelled and full wave simulated results shows good agreement.

Design and fabrication of microfluidic devices integrated with an open‐ended MEMS probe for single‐cell impedance measurement

When an electrical current with a low frequency is applied to a cell, the current passes through the outside of the cell. Thus, impedance measurements at low frequencies cannot be used to determine the pathological change of the cellular organelle taking place inside the cell. However, increasing the frequency of the electrical current makes the capacitive impedance of the cell decrease, allowing the electrical current to flow through the cell. This study presents the design and fabrication of a microfluidic device integrated with a coplanar waveguide open-ended micro-electro-mechanical-systems (MEMS) probe for the impedance measurement of the single HeLa cell in frequencies between 1 MHz and 1 GHz. The device includes a poly-dimethlysiloxane (PDMS) cover with a microchannel and microstructures to capture the single HeLa cell and a conductor-backed CPW fabricated using a silicon chip and two printed circuit boards (PCB). The effects of the substrate on the characteristic impedance of the conductor-backed coplanar waveguide (CBCPW) structure were investigated under three conditions by utilizing a time-domain reflectometer (TDR). Finally, impedance measurements using the proposed device and a vector network analyzer (VNA) are demonstrated for de-ionized (DI) water, alcohol, PBS, and a single HeLa cell.

Benzocyclobutene as Substrate Material for Planar Millimeter-Wave Structures: Dielectric Characterization and Application

The application of benzocyclobutene (BCB) polymer as dielectric substrate material for millimeter-wave microstrip structures is investigated in this paper to face the problem of large losses due to standard dielectrics in the high microwave range. Dielectric properties of BCB are characterized from S-parameter measurements on a conductor-backed coplanar waveguide (CBCPW) using the polymer as substrate material. Excellent features, with a low loss tangent and a stable dielectric constant, are demonstrated within the measurement range from 11 GHz to 65 GHz. As a validation of BCB high frequency performances, the design and experimental characterization of a V-band array on BCB substrate is presented. Measurement results on both matching and radiation characteristics of the millimeter-wave array are discussed.

Characterization of Fully Embedded RF Inductors in Organic SOP Technology

In this paper, we investigate fully embedded circular spiral inductors in multilayered organic packaging substrate for radio-frequency (RF) and microwave applications. The proposed spiral inductors are designed with circular geometry to improve their quality factors and the vertically stacked geometry is utilized to reduce the component area resulting in the increment of packaging density. And also the embedded circular spiral inductors are designed with conductor backed coplanar waveguide (CBCPW) structures for utilizing them directly for compact RF modules and systems. They are evaluated and optimized by varying their geometry parameters such as a number of turns, inner diameter, and embedded layer. These embedded inductors are accurately designed and analyzed by 3-D EM simulation and equivalent circuit modeling. The planar circular spiral two-turn inductor has inductance of 8.6 nH and maximum quality factor of 67 at 1 GHz. The vertically stacked circular spiral two-turn inductor has inductance of 10.2 nH and maximum quality factor of 66 at 1 GHz. The size of the vertically stacked inductor is approximately 70% of the planar one. The measured performance characteristics are well matched with the 3-D EM simulated ones.

A Novel Transition-Included Multilayer Filter

A novel transition-included multilayer filter is proposed with the associated electromagnetically coupled transition from conductor-backed coplanar waveguide to stripline designed as a part of the bandpass filter. Specifically, a filter equivalent-circuit model is introduced with the transformer turn ratio to specify the impedance-transformation characteristic of the transition. The proposed transition-included multilayer filter is then designed by simultaneously taking both embedded stripline resonator circuits and associated transitions into consideration. Being designed along with the transition, the implemented filter occupies a size only half of the conventional filter while still achieving the same specifications. The implemented filter does not require bond wires or air bridges, thereby reducing the response shift caused by misalignment in fabrication. Finally, the measurement and simulation results are presented and good agreement between them is observed.

Compact Ultra-Wideband Conductor-Backed Coplanar Waveguide Bandpass Filter With a Dual Band-Notched Response

This work presents a novel ultra-wideband (UWB) bandpass filter (BPF) based on a conductor-backed coplanar waveguide structure with tunable transmission zeros. The symmetrical UWB BPF, which consists of the broadside-coupled transitions and the stub resonators in double-layer configuration, achieves a UWB bandwidth with transmission zeros. For characterizing this structure, the equivalent-circuit model is established to realize a four-pole response with two transmission zeros located close to the passband edges. To eliminate the interference of the coexisting wireless local area network (WLAN) within the UWB spectrum, two slotlines are symmetrically arranged on the ground plane of UWB BPF to generate the band-notched frequencies at 5.2 and 5.8 GHz simultaneously. The proposed UWB BPFs have the advantages of compact size, low insertion loss, good selectivity, and flat group delay. All results obtained from the equivalent-circuit model and the full-wave simulation are verified by measurements.

High-Q Circular LTCC Resonator Using Zigzagged Via Posts and a $\lambda/4$ Short Stub for Millimeter-Wave System-on-Package Applications

This paper presents two high-Q circular resonators utilizing low temperature co-fired ceramic (LTCC) multilayer circuits for millimeter-wave system-on-package applications. A resonator including zigzagged dual-row via posts for tightly confining electromagnetic energy as a metallic boundary wall will be presented. Another resonator containing the zigzagged dual-row via posts and a lambda/4 short stub on a feeding via post in the circular resonator is used for transmitting energy in the resonator to output load without losses. Simple theories for obtaining high-Q factors using zigzagged dual-row via posts and the feeding technique with the lambda /4 short stub are derived. A total of four layers are used to construct the resonator with a height of 300 mu m (three layers); an additional layer is used for the probe excitation and signal feeding line. The signal feeding line is employed to connect a negative resistance generator monolithic microwave integrated circuit ((-)R MMIC) that consists of conductor backed coplanar waveguide (CBCPW), which is implemented on a layer. A CPW-type double bond wire connects the resonator and (-)R MMIC. The measurement results show that the first and second resonant modes are TM010 at 29.75 GHz and TE010 at 46.75 GHz, respectively. Although the unloaded Q value of the conventional resonator is 204, the proposed resonator with zigzagged dual-row via posts achieved an unloaded Q value of 249, which is a 22.1% improvement. Further, the new resonator with the lambda/4 short stub and zigzagged dual-row via posts yielded an unloaded Q of 296, an improvement of 45.1% for the first resonant mode. In order to verify the resonator performances, the oscillator integrating the proposed resonator is evaluated. The measured output power and phase noise of the oscillator is 18.8 dBm at 27 GHz and -104.67 dBc/Hz at 1 MHz offset, respectively. It can be implemented easily without requiring additional processes or any degradation of performance and therefore is suitable to implement in high integrated systems for millimeter-wave applications.