Low-cost Printed Circuit Board Research Articles

Packaging and Antenna-Assembled Hybrid Stacked PCB with Novel Vertical Transition for 39 GHz 5G Base Stations

This paper proposes a novel packaging and large-scale antenna-assembled structure for a printed circuit board (PCB) that reinforces productivity, facilitates cost reduction, and maintains reliability. This was achieved by splitting the antenna from the main board and packaging it into a radio-frequency integrated circuit. In addition, two innovative solutions—an externally attachable flexible PCB antenna and a PCB-embedded coaxial line—are introduced to overcome the degradation in antenna performance and vertical RF transition loss in the proposed low-cost hybrid PCB. First, the proposed externally attachable flexible PCB antenna and a parasitic aircoupled antenna, which were easily assembled on the PCB, achieved an antenna efficiency of 95% and an impedance bandwidth of 7 GHz. Second, the fabricated coaxial line exhibited enhanced impedance matching over a wide frequency range of 30–40 GHz and improved insertion loss of approximately 1.4 dB. Furthermore, the packaged antenna, composed of 256 dual-polarized antenna elements per stream, incorporated a 39 GHz CMOS-based 16-channel phased-array transceiver IC. The set-level beam-forming measurements were verified considering an effective isotropic radiated power of 55 dBm at boresight and a steering range >±60°. In addition to being suitable for mass production in terms of cost and reliability, the proposed structures and solutions met the required antenna and beam-forming performance for commercial 39 GHz base stations without sacrificing performance.

Development of a slow-wave artificial dielectric substrate-based microstrip line in X band

This paper presents a slow-wave artificial dielectric substrate for planar microstrip device miniaturization. The proposed substrate supports the improvement of the permittivity of a given substrate, and in turn offers guided wavelength reduction, leading to obtaining size reduction using low cost printed circuit board (PCB) process. In this structure, two rows of metal vias are located on either side of a microstrip line (ML), which are connected to the ground plane of the substrate. In addition, a row of metal mushroom-shaped vias is placed and connected at the center of the line, which is inserted inside the dielectric media. This would lessen the effective distance between the microstrip line and the ground, and so, the capacitance per unit length is increased leading to obtaining a slow-wave substrate. The proposed structure is numerically investigated using full wave software for specified parameters and the microstrip line characteristics are compared with those of the conventional line. A prototype of the introduced line is implemented and its measured propagation features, including phase constant and effective permittivity, are reported. Results show a perfect agreement with those of simulation, which confirms that a 50.6% longitudinal size reduction is feasible.

Efficient beam splitting using zero-load-impedance metagratings.

Metagratings with zero load impedance are proposed to achieve efficient beam splitting. Different from previously proposed metagratings that require specific capacitive and/or inductive structures to achieve load impedance, the metagrating proposed here consists solely of simple microstrip-line structures. Such a structure overcomes the implementation constraints such that low-cost fabrication technology can be applied for metagratings operating at higher frequencies. The detailed theoretical design procedure is presented together with numerical optimizations to achieve the specific design parameters. Finally, several reflection-type beam-splitting devices with different pointing angles are designed, simulated, and experimentally measured. The results show very high performance at 30 GHz, paving the way to simple and low-cost printed circuit board (PCB) metagratings at millimeter-wave and higher frequencies.

D-Band Air-Filled Substrate Integrated Waveguide (AFSIW) and Broadband Stripline to AFSIW Launcher Embedded in Multi-Layer PCBs

We report <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$D$</tex-math> </inline-formula> -band air-filled substrate integrated waveguides (AFSIWs) with solid copper sidewalls fabricated inside a multi-layer printed circuit board (PCB) with broad wall width of 1.6 mm and cavity height of 300 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu$</tex-math> </inline-formula> m. Measurements show a loss of 0.07–0.08 dB/mm across 115–155 GHz. This result is the first demonstration of an AFSIW above 100 GHz in a low-cost mass manufacturable PCB and has the lowest loss compared to reported planar PCB lines or substrate integrated waveguides (SIWs) in PCBs and Interposers. We also introduce a broadband stripline to the AFSIW launcher using a broad wall transverse slot which offers ease of manufacturability over existing transitions having a measured insertion loss of 1.1 dB and 27% bandwidth. The combination of a low-loss AFSIW and wideband launcher allows both striplines and AFSIWs to coexist in the same multi-layer PCB.

High Gain and Wideband Antenna-in-Package Solution Using Fan-Out Technology

AbstractThe technology of fan-out wafer level packaging (FOWLP) has been widely adopted for millimeter wave antenna-in-package (AiP) system integration with low interconnection parasitic parameters. Present AiP solutions using FOWLP technology generally form antenna pattern on redistribution layer, which brings design inconvenience. In our work, a low-cost printed circuit board RO4350B laminate for substrate-integrated waveguide (SIW) antenna with a relatively large size is integrated, forms a three-dimensional stacked structure. The AiP employs a right-angle transition board embedded in epoxy molding compound (EMC), which transmits millimeter-wave signal to the SIW antenna stacked on the backside of EMC. The SIW antenna consists of 4 × 4 radiation slots with modified magneto-electric dipole for bandwidth enhancement. The measured gain is 14dBi at 60 GHz with bandwidth beyond 55–65 GHz. The three-dimensional AiP structure improves heat dissipation, no extra thermal design is needed for applications under 0.5 W mm-wave chip power consumption. The AiP module is manufactured and measured on the test board. The proposed approach is a convenient solution for wide band and high gain millimeter wave AiP system integration.

Enhancing the repeatability and sensitivity of low-cost PCB, pH-sensitive field-effect transistors

Discrete, extended gate pH-sensitive field-effect transistors (dEGFETs) fabricated on printed circuit boards (PCBs) are a low-cost, simple to manufacture analytical technology that can be applied to a wide range of applications. Electrodeposited iridium oxide (IrOx) films have emerged as promising pH-sensitive layers owing to their theoretically high pH sensitivity and facile deposition, but typically exhibit low pH sensitivity or lack reproducibility. Moreover, to date, a combined IrOx and dEGFET PCB system has not yet been realised. In this study, we demonstrate a dEGFET pH sensor based on an extended gate manufactured on PCB that is rendered pH sensitive through an electrodeposited IrOx film, which can reliably and repeatably display beyond-Nernstian pH response. Using a combination of complementary surface analysis techniques, we show that the high pH sensitivity and repeatability of the dEGFETs are dependent on both the chemical composition and critically the uniformity of the IrOx film. The IrOx film uniformity can be enhanced through electrochemical polishing of the extended gate electrode prior to electrodeposition, leading to dEGFETs that exhibit a median pH sensitivity of 70.7 ± 5 mV/pH (n = 56) compared to only 31.3 ± 14 mV/pH (n = 31) for IrOx electrodeposited on non-polished PCB electrodes. Finally, we demonstrate the applicability of these devices by demonstrating the detection and quantification of ampicillin due to β-Lactamase enzyme activity, thus laying the foundation for cheap and ubiquitous sensors which can be applied to a range of global challenges across healthcare and environmental monitoring.

Dual-Band 28- and 39-GHz Phased Arrays for Multistandard 5G Applications

This article presents a 32-element 28/39-GHz dual-band phased array for fifth-generation (5G) communication systems. The array is based on separate sets of SiGe transmit/ receive (Tx/Rx) beamformer chips to realize independent dual-beamforming capabilities at orthogonal linear polarizations. The beamformer chips are integrated with an <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$8 \times 4$ </tex-math></inline-formula> dual-band stacked patch antenna array on a low-cost printed circuit board (PCB) and grouped together using two different Wilkinson networks to form two separate beamforming systems. The dual-band array demonstrates a measured effective isotropic radiated power (EIRP) of 40–42 dBm at the 28- and 39-GHz bands. The array is capable of scanning ±55° in the 28-GHz band and ±40° in the 39-GHz band, both in the azimuth plane. In simultaneous dual-frequency dual-beam operation with the 28-GHz band on the V-pol. and the 39-GHz band on the H-pol., spectrum measurement shows that the array has no visible intermodulation products between the 28- and 39-GHz beams. Also, complex modulation measurements with 64-QAM waveforms show < 3% error vector magnitude (EVM) at an EIRP of up to 36-dBm EIRP for both beams radiating together and without interference with each other. This work demonstrates the first millimeter-wave (mm-wave) 5G dual-band array and paves the way toward multistandard systems.

Design and Development of a Low-cost Integrated Dosimeter for External Beam Dosimetry in Radiation Oncology.

Radiation dosimeters play a crucial role in radiation oncology by accurately measuring radiation dose, ensuring precise and safe radiation therapy. This study presents the design and development of a low-cost printed circuit board (PCB) dosimeter and an integrated electrometer with sensitivity optimized for dose rates intended for use in megavoltage radiation therapy. The PCB dosimeter was designed in KiCad, and it uses a low-cost S5MC-13F general-purpose 1 kV 5A power diode as a radiation detector. The dosimeter is calibrated against a known dose derived from an ionization chamber and tested for dose linearity, dose rate dependence, field size dependence, and detector orientation dependence. The observed average dose differences between the delivered and measured doses for most measurements were found to be < 1.1%; the dose rate linearity between 100 MU/min and 1400 MU/min was found to be within 1.3%. This low-cost architecture could successfully be adapted further for a scalable, cost-effective dosimetry solution through firmware or circuit design.

A circularly polarized pyramidal horn antenna based on substrate integrated waveguide

A circularly polarized pyramidal horn antenna based on substrate integrated waveguide (SIW) technology is proposed and developed for Ku-band applications. The proposed horn antenna is excited by the upper and lower SICL differential feed networks placed vertically to each other, so that two orthogonal waveguide modes with the equal amplitude are generated at the horn aperture. A 90° coupling network based on SICL technology is proposed to achieve a 90° phase difference between the two orthogonal waveguide modes, thus realizing the function of left-hand circular polarization (LHCP) and right-hand circular polarization (RHCP) of the horn antenna. In addition, in order to make the phase distribution of the horn aperture more uniform, a cross metal strip structure at the horn aperture is proposed, thereby improving the radiation efficiency. The proposed horn antenna is manufactured by using low-cost printed circuit boards (PCBs) process. The measured results show that the proposed circularly polarized pyramidal horn operates at center frequency 12.5 GHz, the measured gain is 8.4 dBi, the relative standing wave and axial ratio (AR) bandwidth are approximately 24% and 5%, respectively. And the radiation aperture efficiency is as high as 78.5%. The developed circularly polarized pyramidal horn antenna can be applied in the field of satellite communications.

A rapid, sensitive, and simple-to-use biosensor for on-site detection of attomolar level microRNA biomarkers from serum extracellular vesicles

On-site detection of microRNAs in blood-borne extracellular vesicles is important for the timely diagnosis of various diseases and physiologic conditions, including pregnancy status. This work developed a rapid, highly-sensitive capacitive biosensor to detect bovine embryonic mortality-related microRNA, miRNA-16b, in serum extracellular vesicles. The sensor was developed to achieve rapid, highly sensitive and specific detection of miRNA-16b, based on AC electrokinetically accelerated capacitive detection of DNA probe-microRNA hybridization. Using interdigitated electrodes functionalized with complementary DNA probes, this sensing method integrated capacitive measurement with simultaneous AC electrokinetic convection of analytes. Consequently, trace level microRNAs can be quantitatively detected in 30 s, with a detection limit of 22 aM from analytical buffer and 323 aM from neat serum over a linear dynamic range from 0.1 fM to 1 pM. The work also developed a simple and rapid pretreatment protocol to release miRNAs from extracellular vesicles in serum. As a result, the sensor can yield results from serum samples in minutes and diagnose embryonic mortality at day 17 of gestation with a sensitivity of 90.00% and specificity of 88.89% for clinical bovine serum samples. The sensor is fabricated from low-cost printed circuit board electrodes and is mass-production friendly. This rapid and sensitive sensor provides a foundation technology for the development of on-site diagnosis in various human and animal health applications.

A D-Band Multichannel TX System-in-Package Achieving 84.48 Gb/s With 64-QAM Based on 45-nm CMOS and Low-Cost PCB Technology

A high-data-rate <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$D$ </tex-math></inline-formula> -band transmitter (TX) module cointegrating a dual-channel TX integrated circuit (IC) in 45-nm CMOS partially deplated silicon-on-insulator (PDSOI) technology and an antenna is presented. The proposed system-in-package is based on an innovative channel-bonding technique and is fabricated using a low-cost printed circuit board process. The IC consists of two upconversion chains, including on-chip millimeter-wave local oscillator generators. The emitted signal is composed of eight channels, each one having 2.16-GHz bandwidth, organized in two sets of four channels at the intermediate frequency (IF) band (around 61.56 GHz) that are upconverted to two adjacent subbands centered at 148 GHz. Then, the two subband signals are combined off-chip using a substrate integrated waveguide diplexer and radiated by a patch antenna array realized on the same package. The output spans from 139.3 to 156.6 GHz. The total equivalent isotropic radiated power is 8.3 dBm. An 84.48-Gb/s data rate is achieved with 64-QAM. The module consumes 600 mW from a 1-V supply and occupies a compact area of 12 <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> 6 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> .

Simplified Fe modeling of the PyCubed PCB complete with components for CubeSat missions

CubeSat nano-satellites are, to date, the cheapest independent mean of bringing a payload into orbit. The most frequent cause of failure for this kind of launches is the mechanical failure of electronic boards or soldered electronic elements due to vibrations or shocks. For this reason, the numerical finite element design and experimental verification phases of printed circuit boards (PCBs) with soldered components are extremely delicate and critical in the assessment of the integrity of the boards during launch. In simulating the mechanical behaviour of PCBs it is important to consider the material properties, the geometry, and the type of components mounted on them. Possibly the most widely used open-source CubeSat PCBs are the PyCubed. While these avionics platforms, programmable entirely in Python, are radiation-tested and integrate many control features into a single low-cost PCB, they lack of a proper mechanical characterization. Indeed, we believe that the knowledge of the dynamic behaviour of this PCB is crucial to achieve high-reliability CubeSats and to improve the mission success rates. For this reason, this paper will not only provide a mechanical and physical characterization of the PyCuded open-source printed circuits; but above all, it will generate an innovative simplified and reliable numerical model of the PCB that reflects the dynamic behaviour of the complete motherboard of components during the launch. To support and to complete the analysis, numerical/experimental modal comparisons will be used to validate the proposed models. In this way, all designers of PyCubed PCBs will be able to simulate, as realistically as possible, the complete mechanical behaviour of the printed circuit in the presence of components, reducing time, costs, and design risks. The approach the authors proposed, could also be used to model other generic types of printed circuits boards.

A 77-GHz Low-Conversion-Loss Fourth-Harmonic Mixer on SISL Platform

This letter presents a 77-GHz low-conversion-loss (CL) fourth-harmonic mixer based on the substrate-integrated suspended line (SISL) platform. Based on the traditional stub-type harmonic mixing structure, we add several additional transmission lines, which will participate in the impedance matching of the diode together with stubs to reduce the CL. A 3-D electromagnetic (EM) diode model is established for accurate simulation at millimeter-wave frequency. The presented SISL mixer was fabricated by the low-cost printed circuit board (PCB) process and was self-packaged in FR4 substrates. When the local oscillator (LO) frequency is 19.45 GHz and the radio frequency (RF) is 78 GHz, the minimum CL is 12.2 dB under an LO input power of 12 dBm. This mixer is suitable for 77-GHz automotive anti-collision radar systems.

A Multiband/Multistandard 15–57 GHz Receive Phased-Array Module Based on 4 × 1 Beamformer IC and Supporting 5G NR FR2 Operation

This work presents a 15&#x2013;57 GHz multiband/ multistandard phased-array architecture for the fifth-generation (5G) new radio (NR) frequency range 2 (FR2) bands. An eight-element phased-array receive module is demonstrated based on two four-channel wideband beamformer chips designed in the SiGe BiCMOS process and flipped on a low-cost printed circuit board. The SiGe Rx chip employs RF beamforming and is designed to interface to a wideband differential Vivaldi antenna array. Each channel consists of a low-noise amplifier (LNA), active phase shifter with 5-bit resolution, variable gain amplifier (VGA), and differential-to-single-ended stage. The four channels are combined using a wideband two-stage on-chip Wilkinson network. The beamformer has a peak electronic gain of 24&#x2013;25 dB and a 4.7&#x2013;6.2 dB noise figure (NF) with a &#x2212;29 to &#x2212;24 dBm input <inline-formula> <tex-math notation="LaTeX">$P_{\boldsymbol {1\,dB}}$ </tex-math></inline-formula> at 20&#x2013;40 GHz. The eight-element phased-array module also achieved ultra-wideband frequency response with flat gain and low-system NF. The phased array scans &#x00B1;55&#x00B0; with <inline-formula> <tex-math notation="LaTeX">$ &lt; -12$ </tex-math></inline-formula>-dB sidelobes demonstrating multiband operation. A 1.2-m over-the-air (OTA) link measurement using the eight-element Rx module supports 400-MHz 256-QAM OFDMA modulation with &#x003C; 2.76&#x0025; error vector magnitude (EVM) at multiple 5G NR FR2 bands. To the author&#x2019;s knowledge, this work achieves the widest bandwidth phased array enabling the construction of multistandard systems.

A Wide-Band High-Efficiency Hybrid-Feed Antenna Array for mm-Wave Wireless Systems

A wide-band and high-efficiency planar antenna array with a novel hybrid-feed structure is proposed in this article. By combing the coaxial-line feed magneto-electric (ME) dipoles with the aperture coupled dielectric cavity, a hybrid-feed 2 × 2-unit ME-dipole sub-array is invented. The low-loss ridge gap waveguide (RGWG) corporate-feed network is used to replace the high-loss substrate-based feed networks and high-cost RWG feed networks. New forms of RGWG H-plane divider are designed to build the RGWG feed network. An 8 × 8-unit ME-dipole antenna array is designed and fabricated to verify the validity of the array. The radiation part consists of two layers of a low-cost printed circuit board (PCB), and the feeding part consists of two copper plates manufactured by computer numerical control (CNC) milling. Measured results show that a relative bandwidth of 16.4% with |S11| &lt; −10 dB is achieved, with a maximum radiation efficiency of 85%. The stable symmetric radiation patterns are observed in both the E-plane and H-plane, covering the operation band. Based on the measured results, a 16 × 16-unit ME-dipole antenna array is simulated. Results indicate that the proposed array has wide-band and high-efficiency features, which is suitable for large-scale array design in mm-wave wireless systems.

A 1024-Element Ku-Band SATCOM Dual-Polarized Receiver With &gt;10-dB/K G/T and Embedded Transmit Rejection Filter

This article presents a 1024-element dual-polarized Ku-band (10.7–12.7 GHz) satellite communication (SATCOM) receive (RX) phased array. The array consists of four 16 $\times16$ subarray tiles, each of which comprises 64 eight-channel beamformer chips, 256 dual-channel low-noise amplifiers (LNAs), and 256 dual-polarized antennas built on an affordable printed circuit board (PCB). The antennas spaced at $\lambda $ /2 spacing at 12.2 GHz in an equilateral triangular grid allow scanning up to x±70° in all planes while maintaining a cross-polarization level $ dB. The use of LNAs just after the antennas enables a low-noise operation with an antenna gain-to-noise temperature (G/T) of 10.5 dB/K ( $T_{\mathrm {ant}} =20$ K) at broadside while maintaining a directivity of 34 dB at 11.7 GHz. Also, a two-pole/two-zero filter is placed between the LNA and the beamformer chip to greatly attenuate any transmit leakage signal at 14–14.5 GHz. The lightweight, low-cost PCB with all silicon chips and a thickness of 3.4 mm presents a viable candidate for Ku-band SATCOM ground and Satcom-On-The-Move (SOTM) terminals.

Prototyping of a Low-Cost Ion-Selective Electrode Sensor Unit for Determination of Lead Ions in Aqueous Samples

Exposure to lead via drinking water is a substantial health hazard. The current common practice of measuring lead levels in drinking water is to use analytical chemical analysis that involves sophisticated laboratory instruments. As lead contamination in drinking water is often a close-to-home contamination caused by corroded lead service pipes connecting households to main lines or lead-based pluming within the households, a low-cost and portable device that can be conveniently deployed to individual households to monitor lead levels in drinking water would offer consumers the opportunity to obtain first-hand information about the lead levels in their drinking water. The main objective of this study is to develop and prototype a portable low-cost device for detecting lead levels in drinking water. The lead-detecting device consists of two primary components: lead ion-selective electrode (ISE) sensing membrane and a microcontroller-based measuring unit. ISE membrane has proven to show low detection limits, good selectivity, low cost and great potential to be integrated in a miniature device. The ISE membrane in this study utilized polymeric membrane as the matrix with lead-selective ionophores embedded in the matrix. Hydroxyl type Vinyl Chloride-vinyl Acetate Terpolymer was used to create polymeric membrane matrix and allowed for all components to be housed in the membrane. The selected ionophore was Tert-Butylcalix(4)Arene-Tetrakis with its primary function is to differentiate and transport a specific ion (in this case, Pb2+ ions) through a membrane. A limit of detection of 1.0 ´ 10-8 M was achieved along with a linear Nernstian response over a lead concentration range from 1.0 ´ 10-8 M to 1.0 ´ 10-4 M. Durability test of the membrane showed a lifetime close to 30 days. A low-cost printed circuit board (PCB) was custom designed and created as an amplification unit to measure the ISE’s electromotive force (EMF). The custom-built device was able to capture the limit of detection (LOD) of the ISE sensing membrane and showed reasonably good consistency in comparison to measurements from commercial potentiostat.

Reconfigurable Binary-Amplitude Fresnel Zone Plate for Millimeter-Wave Beamforming

This article presents a reconfigurable Fresnel zone plate (FZP) operating at 30 GHz with a low-cost printed circuit board (PCB) process. In general, limited fabrication tolerance greatly limits the optimal design of reconfigurable unit cells at millimeter-wave frequencies. In this work, the freedom of the unit-cell design is improved using a fixed I-shaped element as an impedance matching layer. In addition, <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$N +M$ </tex-math></inline-formula> control lines like those of the conventional display grid are employed to control <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$N\times M$ </tex-math></inline-formula> cells in the E- or H-plane. The transmittance of the unit cell was measured to be–3.5 and–24.5 dB in the transparent mode and opaque mode, respectively, at 30 GHz. A binary-amplitude FZP prototype with <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$32\times32$ </tex-math></inline-formula> elements exhibited ±40° beamforming on both the E- and H-planes with a maximum gain at the broadside of 9 dBi. The measured power dissipation was approximately <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.31~\mu \text{W}$ </tex-math></inline-formula> per single scan at 30 GHz, which is less than 1/100.000 that of the conventional phased array system. Finally, the beamforming of various 5G signals was experimentally demonstrated without signal degradation using the FZP prototype.

PCB mounted sensor with high sensitivity SWNT-Based devices for gas sensing applications

In this paper, the fabrication of aligned semiconducting single-walled carbon nanotube (SWNT) devices on a thermally grown silicon dioxide (SiO2) over silicon (Si) substrate is presented. The SWNTs are aligned between the nickel fingers that are patterned on the substrate. Subsequently, the fabricated devices are bonded onto a low-cost printed circuit board (PCB) with wire bonder. The mounted sensors have been tested for carbon dioxide (CO2) gas, acetone, and isopropyl alcohol (IPA) vapor sensing at room temperature. The sensitivity values of 27% for the concentration of 15000 ​ppm of CO2, 52% for the concentration of 7000 ​ppm of acetone, and 67% for the concentration of 900 ​ppm of IPA have been observed with good response and recovery times. The fabricated sensors show better performance than the already reported sensors.

Programmable Metasurface Based on Substrate-Integrated Waveguide for Compact Dynamic-Pattern Antenna

A programmable metasurface based on a substrate-integrated waveguide (SIW) is proposed to realize a dynamic-pattern antenna, which satisfies the critical needs of low cost, ease of manufacturing, and easy integration with planar circuits in real-life applications. The proposed metasurface consists of 16 elements of complementary electric- <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LC</i> resonators that are etched on the top layer of the SIW. Each element is installed with two p-i-n diodes to reach different states, which are controlled by a dc bias signal through a via from the backside of a printed circuit board (PCB). Both the element parameters and their positions along the SIW are carefully designed for better performance as an antenna. By utilizing different diodes’ tuning schemes, the phase difference between the radiating elements can be dynamically changed, thereby realizing antenna-pattern generation and reconfiguration in real time. Experimental results show that the proposed metasurface can generate not only narrow-to-wide steerable directive beams but also complex multibeam patterns by programming different digital codes. A prototype is fabricated with low-cost PCBs, and good agreements among the simulated and measured patterns are observed. The proposed SIW-based metasurface has a great potential for applications in dynamic-pattern-enhanced microwave imaging, radar, and communication systems.