Circuit Board Technology Research Articles

A Multipolarized Planar Phased Array for LEO SATCOM Applications

This letter presents a scalable multipolarized planar phased array for the low earth orbit satellite communication application. A dual-polarized aperture-coupled patch element antenna is proposed for designing the array, which can provide dual-linear polarization (LP) and dual-circular polarization (CP). The rotated feed technique is adopted to reduce the cross-polarization level. By using 8-channel beamformer chips and the multilayer printed circuit board technology, a phased array prototype with good electromagnetic shielding performance, high integration, and low cost is designed, fabricated, and measured. For dual-LP radiation, it steers up to the scan angles (±50°) with a scan loss less than 3.5 dB, and a cross-polarization level lower than −30 dB in azimuth/elevation plane and −15 dB in diagonal plane. For dual-CP radiation, it steers up to the scan angle (±50°) with a scan loss less than 3 dB and an axial ratio less than 3 dB. The phased array developed in this letter can be scaled to larger arrays and provides feasibility for the production of low-cost phased arrays.

79 GHz Multilayer Series-Fed Patch Antenna Array With Stacked Micro-Via Loading

A wideband compact series-fed patch subarray is proposed for 79 GHz multiple-input—multiple-output (MIMO) radar. The proposed subarray is, for the first time, loaded with stacked micro-vias (SMVs). Two sets of patches in the subarray are fed 180° out-of-phase. A low-cost, high-resolution multilayer printed circuit board (PCB) technology, called “any-layer PCB,” is used to implement the SMVs, which cannot be done by standard high-definition interconnect PCB technology. Moreover, the technology supports small SMVs on different layers; hence, thick machine-drilled vias can be avoided. For comparison, a series-fed patch subarray with no SMV loading is designed. It is shown that SMV loading facilitates a larger overlap of the impedance and gain bandwidths, leading to a larger operating bandwidth. The measured 10 dB impedance and 3 dB gain bandwidths are 15% and 9.6%, respectively. The sidelobe suppression is above 12.9 dB, and the maximum array gain is 12.67 dBi at 79.1 GHz. This subarray is suitable for MIMO radar, as its width is around half-wavelength and the SMVs around it mitigate the crosstalk between the transmitting and receiving arrays.

Partial Reflective Decoupling Superstrate for Dual-Polarized Antennas Application Considering Power Combining Effects

A decoupling design based on metasurface partial reflective decoupling superstrate (M-PRDS) for closely arranged dual-polarized antennas with power combiners is proposed in this communication. Compared with the coupling between each separate antenna element in the array, the introduction of the power combiners makes the mutual coupling between antenna subarrays rearranged and, consequently, more complicated. Therefore, the proposed M-PRDS technology is required to consider the abovementioned power combining effect. The combined mutual couplings are analytically calculated in the first place, and then, a dielectric PRDS (D-PRDS) with given permittivity and height is introduced to create a proper partial reflection for the combined couplings. Finally, an M-PRDS of periodic nonresonate structures with the equivalent electromagnetic parameters as the designed D-PRDS is utilized in this work using simple printed circuit board technology, which not only can achieve the same decoupling effect as the D-PRDS but also possesses the low cost, lightweight, and easy fabrication features. Measurement results of the fabricated prototype composed of 4 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times $ </tex-math></inline-formula> 4 dual-polarized antennas with eight power combiners confirm that all types of mutual couplings can be suppressed to below −25 dB in the operating frequency band (1.7–2.3 GHz). Moreover, the respective port matching, radiation pattern, total efficiency, and envelope correlation coefficients (ECC) between different ports are all in good condition

Experimental investigation and decoupling of voltage losses distribution in proton exchange membrane fuel cells with a large active area

Understanding the local operating state and voltage loss distributions are of great importance to guide the performance improvement of proton exchange membrane fuel cells (PEMFCs). Especially when the active area is large, the uneven electrochemical reaction becomes more severe. However, the current research does not enable the simultaneous monitoring of the multiple operating states and decoupling of the voltage losses in the fuel cell. In this study, a method is established that can obtain the distribution of activation polarization, ohmic loss, and concentration polarization by analyzing the measured data of temperature, humidity, current density, and high-frequency resistance (HFR), which are obtained inside a 320 cm2 and 3 kW level fuel cell stack by using the multilayer printed circuit board (PCB) technology with designed isolation segments. The effects of humidity, operating temperature, and current density on the distributions of output voltage and voltage losses are discussed. Results show that the potential distribution on the surface of membrane exchange assembly (MEA) isn’t uniform in the large active area. The activation polarization gradually increases in the direction of coolant flow and the direction of the cathode flow and the ohmic loss and concentration polarization have opposite distribution characteristics. In addition, when the humidity rises to full humidity, the inhomogeneity of ohmic loss distribution becomes higher with three local increased areas of 20 mV and one decreased area of −20 mV. Higher temperatures can significantly reduce the flooding near the outlet of the active area. When the current density increases, the inhomogeneity of the ohmic loss distribution increases, and the concentration polarization near the cathode outlet of the active area become more severe.

Characterization of a Droplet Containing the Clustered Magnetic Beads Manipulation by Magnetically Actuated Chips

A magnetically actuated chip was successfully developed in this study to perform the purpose of transportation for a droplet containing clustered magnetic beads. The magnetic field gradient is generated by the chip of the two-layer 4 × 4 array micro-coils, which was commercially fabricated by printing circuit board (PCB) technology. A numerical model was first established to investigate the magnetic field and thermal field for such a micro-coil. Consequently, the numerical simulations were in reasonable agreement with the experimental results. Moreover, a theoretical analysis was derived to predict the dynamic behaviors of the droplets. This analysis will offer the optimal operation for such a magnetically actuated chip. This study aims to successfully implement the concept of “digital microfluidics” in “point-of-care testing” (POCT). In the future, the micro-coil chip will be of substantial benefit to genetic analysis and infectious disease detection.

A Comparison of Two Planar Electromagnetic Vibrational Energy Harvesters Designs

Electromagnetic vibrational energy harvesters (EM-VEHs) are generally used to convert ambient vibrations into electricity to energise low-power sensor nodes forming the Internet of Things (IoT). Usually such VEHs comprise of coils and magnets orientated in the vertical direction (z-direction) but these devices tend to be quite bulky and it is hard to integrate them into printed circuit board technology. Configuring coils and magnets in a planar arrangement can lead to a more compact device and to better integration. Two planar EM-VEHs with different coil-magnet arrangements are presented in this paper. Both EM-VEHs (referred as Design 1 and Design 2) employed the same stack of five magnets in Halbach arrangement, magnetic springs and same housing. In Design 1 the stack oscillated below four coils, while in Design 2 four coils were wrapped around the housing and the stack oscillated through them. Harmonic excitation was used to experimentally compare the two prototypes and it was found that Design 2 could generate significant higher output power than Desing 1 (percentage increase ranging from 8292% at a_rms = 0.2g to 559% at a_rms = 0.6g).

A dielectric resonator bandpass filter using printed circuit board technology for wideband application

A dual-mode dielectric resonator based on printed circuit board (PCB) technology formed bandpass filter is proposed for relatively wide bandwidth under low quality factor. By using the low dielectric constant substrate itself to become the core part of the two coupled dual-mode resonators through the PCB process, the proposed design can share the same substrate with other PCB circuits and reduce the installation error. Moreover, benefiting from the dual-mode ( TE 111 y mode and TM 111 z mode) resonator realized by low dielectric constant substrate with low quality factor, the proposed design exhibits the features of low cost and wide bandwidth. A prototype with the center frequency (f0) of 13.85 GHz was demonstrated, which shows the 3-dB fractional bandwidth of 8.34% and the minimum insertion loss of 1.29 dB.

Impact of Slit Configuration on Eddy Current and Supply Current Losses in PCB Winding of Slotless PM Machines

Applied to the production of windings, the printed circuit board (PCB) technology is promising for developing high performance slotless permanent magnet machines, since it allows for winding shapes and topologies that are difficult to obtain with the classical wire technology. However, compared with wire windings, PCB windings are more prone to eddy current losses because of the high width-to-thickness ratio of the conductor cross-section. To counteract these eddy currents, the conventional solution consists of reducing the width of the conductive tracks constituting the winding in conjunction with an increased number of turns. To keep the supply voltage within limits compatible with the power supply, parallel connections of the tracks at the winding terminals are required. This article tackles the eddy current problem differently by adding some slits distributed along the conductive tracks. This amounts to carry out local parallelizations without impacting the motor supply voltage. By means of parametric analyses carried out on different slit configurations and considering their impact on both the supply and eddy current losses, this study shows that a parallel reconnection of successive tracks two by two gives almost the same results as a classical parallel connection of all the tracks, independently of the winding shape. Furthermore, this article concludes that the optimal number of parallel slits is fixed and valid for a large range of nominal speed-torque ratios. However, it is necessary to increase the width of the slits when this ratio becomes very high and it is technically no longer possible to increase the number of slits.

Study on two microchannel coolers with different coupling mechanisms of distributed J-T effect and heat transfer

As a typical characteristic of the microchannel Joule-Thomson (J-T) coolers, the distributed J-T effect significantly impacts the cooling effect. To investigate the coupling mechanism of distributed J-T effect and heat transfer, two micro-coolers are fabricated by Printed Circuit Board (PCB) technology in this study. The throttling device is removed from the micro-cooler with staggered etched pillars (Cooler-Pillars), resulting in an entire coupling of heat recovery and throttling processes. The heat recovery and throttling structures are preserved in a micro-cooler etched with rectangular microchannels (Cooler-REC), and the two processes couple partly. The performance of the two micro-coolers is investigated experimentally and numerically at the inlet pressure of 2.02∼5.12 MPa. The experimental results show that the mass flow rate and total pressure drop of Cooler-Pillars are higher than Cooler-REC at the same inlet pressure. Compared with Cooler-REC, Cooler-Pillars can reach a lower cold end temperature and has a cold-end temperature of 190.6 K in steady-state operation at 5.03 MPa. A steady-state mathematical model is developed and compared favorably with the experimental results. The simulation result shows that at the same inlet pressure, the overall distribution of J-T coefficients and the total temperature drop caused by distributed J-T effect of Cooler-Pillars are higher. It is also found that the overall Nu distribution of Cooler-Pillars is higher than Cooler-REC, and heat transfer is enhanced, leading to an increase of 64.5% in average unit heat transfer at 5 MPa.

Design, simulation and fabrication of non-spiral based fluxgate sensor on printed circuit board (PCB)

This paper presents performance characteristics of non-spiral planar excitation and pick-up micro-coils implemented for a fluxgate sensor with a NiFe magnetic rod core.Using Ansys Maxwell's software, the sensor performance is simulated. Magnetic flux[ϕ], magnetic flux density [B], magnetic field intensity [H], coupling coefficient, inductance [L] and magnetic energy [E] of the coils are simulated for a set of excitation currents. A simple, cost-effective and less complex fabrication method is implemented to fabricate the sensor using Printed Circuit Board (PCB) technology. Non-spiral 5-turn fluxgate sensor of dimensions 50mmx 20mmx 0.5 mm [length × breadth × width] is fabricated and analysed at an excitation current with a fundamental frequency of 500 kHz. Two excitation coils and one pick-up coil are deposited on a horizontal PCB plane and NiFe rod type material is placed on it, which acts as the core. Synthetic glue is spread on the coils; it acts a insulator between the coils and the core. Copper is used for deposition of the both the excitation and pick-up coils. On applying different excitation current, the frequency response of the non-spiral fluxgate sensor is plotted. The sensor demonstrated earth magnetic field strength detection (∼25 μT).

A novel temperature sensor for a calorimetric thermal converter

The calorimetric thermal voltage converter (CTVC) is used as a primary AC voltage standard for the radio frequency range. The vital part of the CTVC is the temperature sensor. The original CTVC has a hand-made multijunction temperature sensor in the form of a spiral constantan wire that is wound around a plexiglass rod, and it is selectively deposited with copper. This article presents research on the possibility of using flexible printed circuit board (PCB) technology to manufacture a temperature sensor for the CTVC. The optimization process enables improvement of the sensitivity of the sensor by around 15%. Due to the relatively low electrical resistance of the sensor, its signal-to-noise ratio (SNR) is similar to those of the best attainable PMJTCs, which utilize temperature sensors fabricated with expensive and complex thin-film technology. The obtained results indicate the applicability of the developed sensor in an efficient calorimetric thermal converter.

Miniaturized Multilayer Surface-Mountable 5G Filter Based on Shielded Spiral Resonator

This brief presents a miniaturized bandpass filter (BPF) based on the shielded Archimedes spiral resonators using the multilayer printed circuit board (PCB) technology. The spiral resonators are incorporated inside a substrate integrated waveguide cavity, resulting in miniaturization by introducing additional coil-to-ground capacitance, and the enhancement of electromagnetic compatibility (EMC) due to the enclosed metal cavity. Detailed theoretical derivation for the resonator is presented to prove its miniaturized effect. A miniaturized 4 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">th</sup> -order BPF for 5G N78 application is developed with the proposed resonators. Compactness is further realized by the multilayer geometrical arrangement, consisting of two types of inter-stage coupling. One is the horizontal edge coupling and the other is the vertical space coupling through the spiral slot. Transmission zeros (TZs) are generated on each side of the passband by source-to-load coupling. The proposed filter is featured with an extremely small volume, low loss, together with good surface-mountable characteristic.

A Minimally Invasive Microwave Ablation Antenna With Highly Localized Ablation Zone

This letter proposes a novel inexpensive microwave ablation (MWA) antenna with a highly localized ablation zone. The antenna is designed based on a substrate integrated coaxial line, at the end of which a serpentine structure is used to radiate microwave power. The serpentine structure can effectively shorten the length of the radiation structure, making the ablation zone more localized. Due to its simple structure, a convenient and inexpensive printed circuit board technology can be used to fabricate the disposable ablation probe. In addition, the proposed topology has a small cross section and, thus, is very suitable for minimally invasive surgery. Simulation analysis and validation experiments have shown that the proposed MWA antenna can provide reliable performance, which means that it can serve as a promising candidate for minimally invasive ablation therapy.

High frequency properties of a planar ion trap fabricated on a chip.

We report on the measurement of the high frequency properties of a planar Penning ion trap fabricated on a chip. Two types of chips have been measured: the first manufactured by photolithographic metal deposition on a p-doped silicon substrate and the second made with printed circuit board technology on an alumina substrate. The input capacitances and the admittances between the different trap's electrodes play a critical role in the electronic detection of the trapped particles. The measured input capacitances of the photolithographic chip amount to 65-76 pF, while the values for the printed circuit board chips are in the range of 3-5 pF. The latter are small enough for detecting non-destructively a single trapped electron or ion with a specifically tuned LC resonator. We have also measured a mutual capacitance of ∼85 fF between two of the trap's electrodes in the printed circuit board chip. This enables the detection of single, or very few, trapped particles in a broader range of charge-to-mass ratios with a simple resistor on the chip. We provide analytic calculations of the capacitances and discuss their origin and possible further reduction.

(Invited) Gold Nanowire Electronic Skins for Wearable Biochemical Monitoring

Next generation of electronic devices will be not only flexible but also stretchable, enabling applications impossible to achieve with existing rigid circuit board technologies. This needs new materials and new design principles. Among various materials of choices, gold has advantages of biocompatibity, chemical inertness, facile synthesis/Surface functionalisation and band-gap-matching with a lot of semiconductors materials. In this talk, I will discuss our newly developed standing gold nanowire-based soft electrochemical biosensing platform in the forms of patches, fibers and tattoos. The unique Janus structures, high surface area and facile surface modification offer materials attributes for next-generation wearable biodianostics for real-time monitoring vitals such as glucose, latctate and catitionic ions.

Study of internal performance of commercial-size fuel cell stack with 3D multi-physical model and high resolution current mapping

The inhomogeneous spatial reaction distributions over the large-scale active area of proton exchange membrane fuel cell stack are critical to the system energy efficiency and lifetime for the automotive applications. In this work, a commercial-size fuel cell stack of 406 cm2 active area is designed with asymmetric reactants flow fields for fuel cell vehicles. To understand the internal performance of the fuel cell, a segmented device with 396 segments is well designed based on the multi-layered printed circuit board technology for high resolution current mapping of the presented stack. Validated by the segmented fuel cell measurements, a 3D multi-physical large-scale model is developed to analyze the detailed distributions of current density, water content and temperature inside the fuel cell stack under different operating conditions. In the counter-flow operation of hydrogen and air, the lowest current density consistently locates around anode inlet while the mid portion of the active area near cathode inlet performs the best. Increasing the air stoichiometric ratio significantly improves the uniformity of current density distribution and the overall performance. The local flow field structures of Cross-flow configurations apparently enhance the in-plane temperature uniformity than the Parallel-flow ones. With the combination of current mapping and coupled modeling, both the distribution trends and local details of internal performance could be analyzed comprehensively to bridge the gap between the stack design and energy efficiency performance.

An Approach to Monitoring of Magnetic Parameters of Cores of a Chain of Spheres. Diagnostics of Different Chain’s Length and Core’s Radius

The basic structural elements of the magnetized granular medium (effectively used, in particular, in apparatus of thin magnetic separation) are granule chains (according to channel-by-channel model), in connection with which there is a need to detail the features of their magnetization. The purpose of the work is to develop and implement an approach to measuring magnetic (micro)flows along the cores of different radius r in the chain of granules using a specially developed (by printed circuit board technology) sensor, with high radius R (15 and 20 mm) spheres available for such measurements.From the data of measuring magnetic (micro)flows data of average induction in each of the quasi-continuous cores of the spheres chain are obtained, as well as data of magnetic permeability and susceptibility of these cores, their magnetization for different values of the intensity of the magnetizing field. It is shown that dependences of mentioned magnetic parameters from number n spheres in a chain are generalized on r /R for different R.These relationships, increasing as n increases due to a decrease in the demagnetizing factor N of any of the cores and the chain as a whole, demonstrate the achievement of individually limiting values of magnetic parameters and corresponding auto-model regions where N→0. At the same time, the transition to each of these regions, manifesting almost independently of r /R and intensity, falls on the value of n = 10–12 = [n]. Thus, in fact, such a criterion value [n] distinguishes chains by sufficiently “long” – when n ≥ [n] and “short” – when 2 ≤ n ˂ [n]. Data of demagnetizing factor for different cores of “short” chains of spheres are obtained and phenomenologically described.

Skew-Symmetric Slotted Waveguide With Mode Select Effect

The mode-selective transmission line (MSTL) has excellent transmission performance due to its wide bandwidth and low loss, which is characterized by the mode-selective effect. In this article, a skew-symmetric slotted waveguide (SSSW) is proposed, whose dominant mode also exhibits the interesting mode-selective effect and transmission performance is similar to that of the MSTL. It is investigated that the dominant mode of the SSSW performs quasi-transverse electromagnetic (TEM) mode at low frequency and quasi-TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">10</sub> mode at high frequency. Then, for fast design, a characteristic impedance formula of the SSSW is derived by the conformal mapping, which has the error less than 3% compared with the finite-element method (FEM). In addition, a microstrip line (MSL) to grounded coplanar waveguide (GCPW) transition is designed to excite the dominant mode of the SSSW, with good transmission of the dominant mode and significant suppression of higher order modes. Finally, the SSSWs with the transitions are fabricated under printed circuit board (PCB) technology and measured with the S21 larger than −2.1 dB and the S11 less than −12.7 dB from dc to 67 GHz, and the attenuation of the SSSW is less than 0.065 dB/mm below 65 GHz. Good eye diagram is obtained with bit error rate (BER) less than <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$10^{-12}$ </tex-math></inline-formula> for the 32-Gb/s data rate.

Wideband RWG-SIW Interconnection With Improved Integration for Millimeter-Wave/Terahertz Application

In this letter, wideband interconnections are proposed to connect metal rectangular waveguide (RWG) and substrate integrated waveguide (SIW) based on printed circuit board (PCB) technology. For the purpose of easy fabrications and micro-assembly processes in millimeter-wave/terahertz (MMW/THz) applications, a standard RWG is used to feed the transition without any manufactures in the metal waveguide. The wideband interconnection structure with improved impedance matching is only designed in a single-layer PCB. Particularly, the novel interconnections are realized by stepped dielectric transformers using PCB technology. These integrations have the advantages of simple structure, low fabrication cost, and easy processes. To demonstrate the scheme, two 220-GHz band interconnections are designed as examples. Back-to-back interconnections are fabricated and measured. The measured results agree well with the simulated results. It can be concluded that the measured insertion and return losses of both single interconnections are better than 0.9 and 10 dB, respectively, in the frequency range from 180 to 240 GHz (28.6%).

Design Optimization of PCB-Based Rotary-Inductive Position Sensors.

This paper introduces a novel methodology to optimize the design of a ratiometric rotary inductive position sensor (IPS) fabricated in printed circuit board (PCB) technology. The optimization aims at reducing the linearity error of the sensor and amplitude mismatch between the voltages on the two receiving (RX) coils. Distinct from other optimization techniques proposed in the literature, the sensor footprint and the target geometry are considered as a non-modifiable input. This is motivated by the fact that, for sensor replacement purposes, the target has to fit a predefined space. For this reason, the original optimization technique proposed in this paper modifies the shape of the RX coils to reproduce theoretical coil voltages as much as possible. The optimized RX shape was obtained by means of a non-linear least-square solver, whereas the electromagnetic simulation of the sensor is performed with an original surface integral method, which are orders of magnitude faster than commercial software based on finite elements. Comparisons between simulations and measurements performed on different prototypes of an absolute rotary sensor show the effectiveness of the optimization tool. The optimized sensors exhibit a linearity error below 0.1% of the full scale (FS) without any signal calibration or post-processing manipulation.