A Broadband CPW-to-Microstrip Modes Coupling Technique

Correlation of printing faults with the RF characteristics of coplanar waveguides (CPWs) printed on nonwoven textiles

Summary form only given. Wireless medical telemetry service is one of the fastest emerging technologies in healthcare industries worldwide. In addition, the proliferation of smartphones is currently serving as a catalyst to the increasing growth in this sector. Based on a secure, close-range wireless body area network (WBAN) which relays the patient's physiological information to a nearby cellular device, a real-time monitoring system for those who require a relatively close medical attention can be realized. Among the physiological parameters, the pulse and the respiration rates are important indicators for wide range of healthcare applications ranging from recreational sports to wireless medical monitoring. Despite the significant advantages, the technical challenges of devising a wearable, sturdy health monitoring device with a reliable radio must be fully resolved. When operating at the industrial, medical and scientific (ISM) radio band, the antenna is expected to be one of the largest components within the device. It is imperative for the antenna to remain low-profile and yet be capable of exhibiting efficient radiation characteristics albeit the detrimental effects of the user's body on the antenna matching and radiation. In this paper, a planar, zeroth-order resonance (ZOR) antenna is proposed for a wearable and detachable electrocardiography (ECG) sensor device. The profile of the proposed antenna topology is minimized using two distinctive techniques: 1.The elimination of vias unlike the conventional mushroom-shaped ZOR topologies. 2. Modeling of the radiator, series capacitance, shunt inductance and the ground on a single printed circuit board (PCB) layer. An air-bridge employed co-planar waveguide (CPW) structure is designed as the antenna feed network between the antenna element and the in-house low power 2.4 GHz RFIC. The overall dimension of the planar ZOR antenna is 15 mm × 9.6 mm × 3 mm when fabricated using a flexible PCB (İr = 2.2, tan = 0.02). The antenna is placed above the main board PCB of the ECG device and subsequently covered with flexible polycarbonate chassis. The radiation properties of the ZOR antenna within the assembled ECG device is studied by placing the device on the surface of the human body model with electrical properties as follows: Skin (ı=1.46 S/m, h=0.5mm), Body fat (ı=0.27 S/m, h=10.5mm), Muscle (ı=1.74 S/m, h=20mm) where h is denoted as the thickness. Simulation and measurements confirm a -10 dB S11 bandwidth of more than 80 MHz and a radiation efficiency of more than 30% in the presence of the human body. Overall, the ZOR antenna is confirmed to feature more than 3.5 m enhanced communication coverage and more than 20% higher antenna radiation efficiency in comparison to that using conventional chip antennas and monopoles under identical measurement conditions.

Two vertical transitions with through silicon vias (TSVs) in 3D die stack are designed and their high frequency electrical characteristics are presented in this paper. The two vertical transitions consist of TSVs for obtaining electrical connection between the die front side and back side. Back side redistribution layer is eliminated in the designs to simplify the fabrication process without sacrificing the electrical performance. Design considerations and guidelines are provided to design high speed TSV structure up to 50 GHz. Different kinds of transmission line interconnects (for instance, microstrip line and coplanar waveguide) are implemented at the input/output extensions for different applications. For both vertical transition designs, the simulated insertion loss is better than 0.65 dB up to 50 GHz while good impedance matching from DC to 50 GHz is obtained with the simulated return loss greater than 14 dB.

This thesis presents a specialization of the integral equation (IE) method for the analysis of three-dimensional metallic and dielectric structures embedded in laterally unbounded (open) layered media. The method remains basically spatial but makes use of extensive analytical treatment of the vertical dependence of the problem in the 2D Fourier-transformed domain. The analytical treatment restricts somewhat the class of structures that can be analyzed. Still, the field of applicability remains very large, and includes most printed circuit and integrated circuit structures. The method is developed in full numerical detail, from first principles down to the properties of new Green's functions and the computation of particular types of convolution integrals. We show how the memory and time complexity are considerably reduced when compared to the requirements of the analysis of general 3D structures. With the newly developed tool, it is possible to deal with some peculiar characteristics of microwave and millimeter-wave circuits and antennas. Most noteworthy among these is the presence of thick metallizations (either electrically, or relative to circuit features). A novel full-wave analysis of arbitrarily shaped apertures in thick metallic screens is presented. This is compared to other methods, both full-wave and approximate, and demonstrated to offer excellent accuracy. Comparison with measured data, obtained from specially constructed prototypes, further validates the new technique. A second application is to the analysis of airbridges in coplanar waveguide (CPW) and slotline (SL) circuits. Comparison of measured and simulated data validates again our technique and provides valuable information about the behavior of CPW-fed slot loop antennas. Among the more specific applications, particular attention is devoted to the analysis and design of submillimeter-wave integrated dielectric lens feeds. These were object of study in the frame of a European Space Agency project, Integrated Front-End Receivers (IFER), which our Laboratory carried out in cooperation with a team at University of Toronto. The analysis method developed in this work encompasses and extends all previous work done at our Laboratory (LEMA) related with the analysis of this kind of feed. Together with the advanced 3D ray-tracing code developed at University of Toronto, it is possible to gain a high degree of insight into the behavior of these integrated receivers.

A 94-GHz phased array antenna using a log-periodic antenna has been developed on a GaAs substrate. The developed phased array antenna comprises four log-periodic antennas, a phase shifter, and a Wilkinson power divider. This antenna was fabricated using the standard microwave monolithic integrated circuit (MMIC) process including an air bridge for unipolar circuit implementations on the same GaAs substrate. The total chip size of the fabricated phased array antenna is 4.8 mm × 4.5 mm. Measurement results showed that the fabricated phased array antenna had a very wide band performance from 80 GHz to 110 GHz with return loss characteristics better than -10 dB. In the center frequency of 94 GHz, the fabricated phased array antenna showed a return loss of -16 dB and a gain of 4.43 dBi. The developed antenna is expected to be widely applied in many applications at W-band frequency.

Dual circular polarization 2 × 2 slot array antenna based on printed ridge gap waveguide technology in Ka band

A novel distributed digital MEMS (micro-electro-mechanical system) microwave phase shifter, fabricated with bulk Si micromachining techniques, is presented. Using a distributed nonlinear transmission line technique, with single crystal silicon based multilayer microbridge structures as loading varactors, this phase shifter delivers true time delay and wideband performance. A micromachining process flow, combining anodic bonding and single crystal silicon etching with heavy boron doping, was developed to fabricate the movable Si-based microbridges over a coplanar waveguide (CPW). An electrostatic voltage, applied between the Si layer of the microbridges (varactors) and CPW ground plane, pulls down the microbridges, effecting a phase shift varying linearly with. frequency. The principle, process and RF performance characterization are described. The actuated phase shifter has achieved 90.2/spl deg/ phase shift at 20.5 GHz, with good reflection loss (-12 dB) in the frequency range of 5-20.5 GHz. The insertion loss is a little high, 3.87 dB, however, due to the lossy substrate of Pyrex 7740 glass and the thin metalization of the CPW.

In this paper, a comparative study between a compact microstrip Zeroth Order Resonant antenna with another coplanar waveguide (CPW) based vialess ZOR antenna is presented. But the drawback of this microstrip based CRLH TL is that a narrow bandwidth of about 0.75% with an improved gain of about 3.6256dB is achieved. In order to circumvent this drawback we demonstrate a vialess CPW fed structure using the same substrate, RT Duroid (5880) (e R = 2.2, h = 1.57mm) and compare the performance of both these antennas. In the CPW fed case we obtain a bandwidth enhancement of about 7.84% with a dumb-bell shaped radiation pattern at phi=90deg (E-radiation pattern). The zeroth order mode obtained in this case is at 2.14GHz while with the microstrip based ZOR antenna, the zeroth order freq is at 3.995GHz with a monopolar radiation pattern at phi=90deg. The CPW fed antenna is easy to fabricate as it is based on a single layer. The drawback of this CPW fed antenna is that the gain reduces to 1.6949dB as the structure is electrically much smaller than the microstrip based ZOR antenna. Simulated results for both the cases are shown. The operational bandwidth of the CPW based ZOR antenna at 2.14 (2.06 to 2.2195) GHz covers the required bandwidths of the IEEE 802.11 for wireless local-area networks (WLAN) applications while in case of the microstrip ZOR antenna, the operational bandwidth at 3.995Ghz and at 3.095 GHz encompasses worldwide interoperability for microwave access (WiMax) standards suitable for point to point multiband applications.

A realization of the quasi-optical (QO) feed concept for linear millimeter-wave (sub-)array antennas is demonstrated in gap waveguide technology. The proposed feed architecture employs an input transition from a ridge gap waveguide (RGW) to a groove gap waveguide (GGW), a radial (H-plane sectoral) GGW section, and a transition to an output RGW array. A design decomposition approach is presented to reduce simulation complexity. Several 20-element QO feed implementations are investigated at W-band demonstrating a 20% relative bandwidth (85–105 GHz), 0.5 dB insertion loss, and a capability of an amplitude taper control within the 10–20 dB range.

Porous anodic aluminum oxide (AAO) has been proposed to be interposer substrate material in recent years. This work is to deliver fabrication and characterizations results of AAO film itself and test structures then, finally, evaluate its possibility to be an interposer material. First, chemical durability test was done in 4 solutions which indicated fabricated AAO was relatively weak against base and acidic solutions which could be improved by adding additional annealing process. Electrical measurements were conducted to probe daisy chain up to 400 nodes, coplanar waveguides (CPW), and embedded solenoid inductors. Data showed linear relationship between numbers of vias and resistance in daisy chain DC measurements; insertion loss from CPW measurement suggested less than 0.2 dB (0.167 dB/mm) insertion loss from 45 MHz all the way to 20 GHz. Embedded solenoid inductors in the current design had quality factor (Q) reaching 41 in 2-turn inductor design. AAO can be a potential interposer material based on our fabrication process and characterization results.

High isolation and low insertion loss is highly regarded for the devices designed for high frequency applications. A compact radio-frequency microelectromechanical systems switch on quartz substrate is presented in this paper. The high isolation is achieved by incorporating two membranes in series and shunt configuration on a single substrate while maintaining the compactness of the switch dimensions. The ohmic and capacitive switch membranes are designed in a cavity over co-planar waveguides on substrate. Spring constant, pull-in voltage, pressure distribution, squeeze film air damping, Q-factor, R, L and C for switch are calculated and analyzed by finite element modeler. Eigenfrequency analysis is also carried out using FEM to analyse the mode shape for first 6 eigenfrequencies. Biasing pads are provided on both ends of the switch for electrostatic actuation. Membranes with low spring constant are designed and optimized to work on same voltage level. Stress on membranes is analyzed and taken care of by the including meanders. This proposed switch is showing excellent isolation of $$75$$75 dB and low insertion loss of $$0.13$$0.13 dB at $$28$$28 GHz with need of actuation voltage of $$22.5$$22.5 V for both membranes in complete switch area of $$0.4$$0.4 mm$$^2$$2. The switch has wide bandwidth of $$30$$30 GHz from K and Ka band with above $$62$$62 dB of isolation.

Design of two different slot-coupled vertical microstrip–microstrip transitions for ultrawideband (UWB) multilayer microwave circuits are introduced. Transitions consist of two stacked substrates with common ground in the middle and two microstrip-feed-lines connected to microstrip patches on the top and bottom. The proposed transitions use broadside coupling between microstrip patches at the top and the bottom layers via a rectangular-shaped slot in the common ground plane (midlayer). The proposed patch shapes are trapezoidal and butterfly shapes, which are capable of achieving broadband characteristics for UWB operation. Extensive parametric studies are performed to address the effect of varying the transition parameters on the coupling value and the operational frequency bandwidth. The simulated results using two simulation programs with two different numerical techniques show that the proposed transitions have low transmission coefficient (less than 1.2 dB) and a high reflection coefficient (better than 16 dB) over the 3.1–10.6 GHz frequency range. Two transition prototypes are fabricated and then tested experimentally using Agilent E8364B PNA Network Analyzer. Experimental results agree well with the simulated ones. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:747–756, 2015

In this paper a new procedure for the spiral Marchand balun design is shown and demonstrated. The size reduction for this component is fundamental to obtain a high level of integration for the radio frequency analog circuits. This work shows a micro-structure that, working as a balun, achieves good performance in phase and amplitude balance, while maintaining minimum size. These results were achieved by performing an accurate theoretical analysis followed by an electromagnetic simulation of the structure. A set of equations are proposed to describe the component behavior and the measurements show a strong agreement with the simulations confirming the quality of the design flow. The balun shows a maximum of 1.5 dB of insertion loss, with 0.1 dB of amplitude imbalance. The phase imbalance reach as a maximum of 7° at 65 GHz. The total occupied area of the balun remain below to 0.01 mm2.

Microwave and millimeter-wave integrated circuits and distribution networks often require two transmission lines to cross over each other. In this paper, experimental measurements and 3D-Finite Difference Time Domain (FDTD) analysis are used to characterize Coplanar Waveguide (CPW) and Finite Ground Coplanar (FGC) waveguide crossover junctions for the first time. It is shown that FGC crossover junctions have approximately 15 dB lower coupling than CPW crossover junctions with no degradation in return and insertion loss.

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.