Flame Resistant-4 Research Articles

Design and analysis of frequency reconfigurable antenna for global positioning system applications

A compact frequency reconfigurable antenna is designed and analyzed in this paper to operate with global positioning system (GPS) and worldwide interoperability for microwave access (WiMAX) applications. The designed antenna is printed on flame resistant 4 (FR4) epoxy substrate with relative permittivity is 4.3, loss tangent of 0.03 and overall substrate with ground (GND) plane dimensions of (54.6x54.6x1.6) mm3 and patch dimensions of (45x45) mm2. The antenna is designed and optimized using computer simulation technology (CST) package through series of parametric studies in order to cover the GPS, WiMAX bands with resonant frequency of 1.229 GHz, 1.575 GHz, and 3.34 GHz. Two triangular slots at the patch sides and single elliptical slot at the middle are etched for the best antenna performance. The designed antenna performs frequency re-configurability by using PIN diode switch at the inset feed to change the operating frequencies from double band operation at (1.575 and 3.34) GHz to single band at 1.229 GHz under S11 ≤-10 dB. The proposed antenna produces accepted simulation results with voltage standing wave ratio (VSWR), maximum radiation efficiency and gain of less than 2.76% and 7.035 dBi respectively.

Design and Simulation “Ha”-Slot Patch Array Microstrip Antenna for WLAN 2.4 GHz

This paper presents a linear 1 × 2 “Ha ( )”–slot patch array microstrip antenna. The proposed design of an array microstrip antenna is intended for Wireless Local Area Network (WLAN) 2.4 GHz devices. From the previous research concerning the single patch “Ha ( )”–slot microstrip antenna, the gain that can be achieved is 5.77 dBi in simulation. This value is considered too small for an antenna to accommodate WLAN devices if compare to a Hertzian antenna. To enhance the gain of microstrip antenna, some methods can be considered using linear 1 × 2 patch array and T-Junction power divider circuit to have matching antenna impedance. The distances between two patches are one of the important steps to be considered in designing the patch array microstrip antenna. Thus, the minimum distance between the patch elements are calculated should be greater than λ/2 of the resonance frequency antenna. If the distance less than λ/2 electromagnetically coupled will occur, vice versa when it is to widen the dimension of the antenna will less efficient. Epoxy substrate Flame Resistant 4 (FR4) with dielectric constant 4.3 is used as the platform designed for the array antenna and it is analyzed using simulation software Computational Simulation Technology (CST) studio suite by which return loss, Voltage Standing Wave Ratio (VSWR), and gain are calculated. The simulation result showed that the designed antenna achieve return loss (S11) -25.363 dB with VSWR 1.1 at the frequency 2.4 GHz, and the gain obtained from simulation is 8.96 dBi, which is greater than 64.4 % if compared to the previous one. The proposed antenna design shows that increasing the number of patches in the array can technically improve the gain of a microstrip antenna, which can cover a wider area if applied to WLAN devices

A novel UWB microstrip patch antenna des for cardio activity monitoring application

Nowadays health care diagnostic applications are preferring microstrip type of antennas effectively. The market for noninvasive and contactless physiological function measurement is growing all the time, and such equipment is useful for tracking the conditions of hospitalized patients. This paper proposes a novel Ultra wideband microstrip patch antenna design that can be used for cardio activity monitoring. Ultrawideband antennas are increasingly being used in short-distance communication links because they can relay a large amount of data over a broad frequency spectrum. It poses little danger to the human body, consumes little power, and is totally compatible with peripheral devices. It has a low chance of human body radiation, as well as low power consumption and high compliance with peripheral devices. As a result, UWB antennas have been regarded as a useful piece of technology for calculating biological data. As signals travel through ultra-wide band antennasover a large frequency spectrum of small signals, less power is needed, and as a result, low noise is tolerated. The suggested microstrip patch antenna is made of FR-4 (Flame Resistant-4) substrate material and resonates at 2.5 to 4.5 GHz. The proposed antenna's simulated VSWR, S-parameters, and radiation pattern have been studied.

Design of CPW-fed MIMO Antenna for Ultra-Wideband Communications

This paper presents a compact multiple input multiple output (MIMO) antenna design with good isolation for ultra-wideband (UWB) applications. The proposed antenna contains two identical monopoles that are placed parallel to each other and which are fed by a 50-ohm coplanar waveguide (CPW). The MIMO antenna is fabricated on a low-cost flame resistant 4 (FR4) substrate with an overall size of 36 × 36 × 1.6 mm3. The designed antenna has a good wideband impedance matching of |S11| <-10 in the UWB frequency range from 3.1 to 14.9 GHz and a good isolation about 13.7 dB in the whole UWB band. The prototype of the design is fabricated and measurement is carried out in order to validate the simulated results. The proposed antenna exhibits an envelope correlation coefficient (ECC) less than 0.01 and a diversity gain (DG) more than 9.9 dB, which means that the antenna has a good performance and good candidates for UWB applications.

그라운드를 전환하여 주파수를 가변할 수 있는 광대역 메타물질 흡수체

In this study, we proposed a wideband frequency tunable metamaterial absorber using a switchable ground plane (SGP). We proposed two fire retardant or flame resistant 4 (FR4) substrate structures for the SGP. An SGP is placed at the middle layer, between the top pattern and the bottom ground plane. The SGP can either be made ground or reactive, by switching the PIN diode ON/OFF. As the frequency is determined by the substrate thickness, the frequency can be switched from the SGP. The proposed absorber is demonstrated by full-wave simulations and measurements. When the SGP is turned on, an absorptivity higher than 90% is achieved from 3.5 GHz to 11 GHz. When the SGP is turned off, an absorptivity higher than 90 % is achieved from 1.7 GHz to 5.2 GHz.

Humidity-sensing performance of layer-by-layer self-assembled tungsten disulfide/tin dioxide nanocomposite

In this article, we demonstrate a humidity sensor based on WS2/SnO2 nanocomposite via layer-by-layer (LbL) self-assembly technique on a FR4 (Flame Resistant 4) epoxy substrate with interdigital electrodes (IDEs). The component, morphology, and chemical state of WS2/SnO2 film was fully examined by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). The humidity sensing characteristics of WS2/SnO2 film sensor were investigated at room temperature. The WS2/SnO2 film sensor exhibited supreme sensing properties, including unprecedented response/sensitivity, rapid response rate, and good repeatability. The WS2/SnO2 film sensor illustrated 36 and 89 times higher responses than that of pure WS2 and SnO2 devices, respectively. To our knowledge, the sensor exhibited the unparalleled response and sensitivity among the existing humidity sensors ever reported. Moreover, the presented sensor demonstrated good performance in monitoring human respiration. We investigated the electrical characteristics of the WS2/SnO2 film by impedance spectroscopy and Bode plots. The equivalent circuit model was established, and the humidity sensitive mechanism of WS2/SnO2 nanocomposite film was systematically investigated. The present work demonstrates that LbL self-assembled WS2/SnO2 nanocomposite is an excellent material candidate for the fabrication of ultrahigh-performance humidity sensor.

355 nm UV laser patterning and post-processing of FR4 PCB for fine pitch components integration

Laser direct patterning of fine pitch features on standard PCB (Printed Circuit Board) was investigated. As a feasibility study, eight parameter sets were selected and the smallest achievable grooves and tracks were determined. Three regular FR4 (Flame Resistant 4) PCB substrates have been experimented with. The first two have respectively 18 µm and 35 µm bare copper conductive layer without finish while the third one has a 18 µm copper layer with ENIG (Electroless Nickel Immersion Gold) finish.Laser patterning of PCB conductive structure is a single step, maskless and purely dry operation expected to allow reaching fine pitch features, even on thick copper layers (≥ 18 µm) for which the traditional chemical wet processes encounter underetch problems. Aside PCB complete structuring, a second objective is to evaluate laser post-processing of standard patterned PCB as an economically viable technique to integrate a few fine pitch components on low cost PCBs. This process is suitable for prototyping and for small and medium series.The widths of the smallest grooves and tracks that we achieved were measured about 11 µm and 19 µm on 18 µm thick cooper layer, 13 µm and 39 µm on 35 µm thick cooper layer, and 11 µm and 38 µm on 18 µm cooper layer with ENIG finish. These values are well below what can be achieved with a wet process. Etching results are presented at high magnification both from the top and from a cross-sectioning perspective. The latter allows observation of the TAZ (Thermal Affected Zone) in the conductive layer and the damages in the FR4.

Nondestructive measurement of complex permittivity by a microwave technique: detection of contamination and food quality

In this paper, we interested of wideband measurement system that permits to characterize high- and low-loss materials according to physical and chemical properties of cheddar cheese and beef. The proposed measurements system, spanning a frequency range of 1–18 GHz, is constituted by one port junction of a small diameter ( mm, mm) coaxial probe and a standard rectangular waveguide. Theoretical reflection coefficient is obtained using the generalized equivalent circuit method that takes into account most of the involved physical phenomena. Thus, the effect of higher order modes as well as the dominant modes is considered. The complex permittivity of material is extracted by minimizing the difference between the theoretical and measured reflection coefficient. The complexity of the electromagnetic analysis does not allow to find an analytical relation between these two parameters. A computer code based on genetic algorithm is developed to numerically solve the inverse problem. To validate this program, we perform measurements on standard materials of known permittivity as air and FR4 (Flame Resistant 4) in the 1–18 GHz range.

Design of a dual-wideband monopole antenna by artificial bee colony algorithm for UMTS, WLAN, and WiMAX applications

In this study, a dual-wideband monopole antenna has been designed and developed for the universal mobile telecommunications system (UMTS), wireless local area network (WLAN), and worldwide interoperability for microwave access (WiMAX) applications. A novel approach integrating artificial bee colony (ABC) with the HyperLynx® 3D electromagnetic platform based on the method of moments has been employed to calculate the design parameters of the monopole antenna performance for the respective target frequencies and return loss. The proposed dual-wideband antenna operates in the dual-frequency ranges of 1.69–3.99 and 4.75–6.22 GHz applicable for the UMTS, WLAN, and WiMAX applications and it is fabricated on the flame resistant-4 substrate plate of 42 × 51 × 1.6 mm3. The performance of the presented monopole antenna is analyzed in terms of gain, radiation pattern, and s-parameter. The input reflection coefficient (S11) parameter and radiation pattern of the antenna are verified through the measurements. The measured values of the antenna parameters are found to match well within tolerable limits with the simulation results. The results illustrate that the presented dual-wideband monopole antenna obtained by using the ABC algorithm exhibits better performance in point of operating bands and s-parameter as compared with the multi-band antennas previously published in the literature.

A Novel Microwave Attenuator on Multilayered Substrate Integrated Waveguide

In this paper, we propose a novel microwave attenuator based on the multilayered substrate integrated waveguide (SIW). The large loss tangent of Flame Resistant-4 (FR-4) material in the Ku band is employed to design a highly lossy SIW resonator cavity as block element for the exploration of this attenuator. The relative permittivity and loss tangent of FR-4 at high frequency are at first experimentally extracted by testing a fabricated ring resonator on FR-4 substrate. Then the characteristics of single unit of this attenuator versus a few critical geometrical dimensions are studied. Next, an equivalent circuit of this single-unit structure is developed to theoretically predict the propagation characteristics of the designed attenuator in an efficient and effective manner. Finally, an example of SIW-based attenuator is designed and measured. The measured attenuation factor agrees with the simulated and predicted ones in the stopband frequency of our concern. In addition, good impedance matching at input and output ports is satisfactorily realized.

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.

A Method for Determining the Dielectric Constant of Microwave PCB Substrates

This paper presents a simple method for determining the dielectric constant of microwave PCB substrates. In the presented method, a bandpass microstrip filter designed on the PCB substrate with a user-predicted dielectric constant value is implemented for a given center frequency. The simulation results of the designed bandpass filter are obtained by the help of microwave design software; XFDTD®. Experimental results regarding the filter frequency characteristic are accomplished by means of a vector network analyzer. The simulation results of the designed filter are modified to overlap with the experimental ones by varying the dielectric constant value. When the simulation and experimental results are overlapped, the value of dielectric constant is accurately selected. In order to illustrate the validity of proposed method, the dielectric constant values of flame resistant-4 (FR4) substrates are acquired at IEEE 802.11b/g and IEEE 802.11a wireless local area network (WLAN) application frequencies. The results obtained by using the presented method agree with the previous studies in the literature.

Characteristics of environmental factor for electrochemical migration on printed circuit board

This study investigates whether electrochemical migration (ECM) is affected by factors such as the printed circuit board (PCB) material, distance between the conductors, bias voltage, contamination and underfill process under water drop (WD), temperature and humidity bias (THB), and polarization tests. The resistance of ECM with polyimide PCB was greater than that with FR-4 (flame resistant-4) PCB. The ECM rate was increased by decreasing the distance between the conductors of opposite polarity and increasing the bias voltage. The cured underfill on PCB protected the ECM growth, while contamination with chlorine ions accelerated the ECM growth.

Characterisation of FR-4 substrate with various plasma treatment conditions

The effects of plasma treatment on the surface of the flame resistant-4 (FR-4) substrate with underfills under various treatment conditions (operating gas, operating time, operating power) are investigated by using contact angle measurement, X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). The plasma treatment on substrate surfaces increased the oxygen containing functional groups or the polar component of the surface free energy, improving the wetting characteristics of the underfills/FR-4 substrates. The plasma treatment conditions which minimised the contact angle between the underfills and FR-4 substrates were an operating power of 300 W and operating time of 180 s under Ar gas atmosphere.

Effect of plasma treatment on adhesion characteristics at interfaces between underfill and substrate

The effects of plasma treatment on the surfaces of the flame resistant-4 (FR-4) and copper substrates are investigated in terms of X-ray photoelectron spectroscopy (XPS), contact angle, and atomic force microscopy (AFM). The adhesion strengths of the underfills/FR-4 substrate and underfills/copper substrate are also studied. As experimental results, the plasma treatments of FR-4 and copper substrate surfaces yield several oxygen complexes in hydrophilic surfaces, which can play an important role in increasing the surface polarity, wettability, and adhesion characteristics of the underfills/substrates. And, the curing temperature ranges of the underfills, which have the maximum adhesion strength of the underfills/FR-4 substrate and underfills/copper substrate, were 140–150 °C.