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In this study, a three‐dimensional bandpass frequency selective surface (FSS) with a new fabrication technology is proposed and designed based on slotlines. The proposed FSS consists of silver paste circuits printed on aramid paper, and is vertically and horizontally arranged to form a periodic array in honeycomb structure. To better understand the design principle of the proposed FSS, the equivalent circuit model (ECM), single‐polarized structure, and dual‐polarized structure are presented and analyzed, respectively. The proposed FSS exhibits a passband at 4.1 GHz with a fractional bandwidth of 71.5% at x‐polarization and 66.2% at y‐polarization with reflectivity less than −10 dB. Moreover, the reflection and transmission coefficients have relative stable properties up to 30° for the oblique incidence. Then, the proposed structure is fabricated and measured to verify the design strategies. The measured and simulated results have reasonable agreement under a large variation of incident angles. [ABSTRACT FROM AUTHOR]

How to monitor the freshness of packaged food, the safety of sealed medicine, or the other substances in sealed space wirelessly and environment‐friendly has become an urgent problem in recent years. After summarizing the theory of the LC sensor, a design of a paper‐based resonator (30 mm × 30 mm × 0.15 mm) consisting of a finger capacitor is proposed in this paper. The sensor is embedded inside the package by adhering it to the package's inner wall. Its response is remotely detected through a readout coil. This paper establishes a circuit simulation model and an electromagnetic simulation model to verify the feasibility of the design. Compared with the real object and the theoretical simulation model, the difference between the results only within 1 MHz, which verifies the correctness of the theory. Additionally, the measured results indicate that the resonant frequency of the resonator shifted from 102.441 MHz to 88.195 MHz, after dropping water on the sensor. Besides, the simple fabrication technology and inexpensive sensor material ensure a low cost, thus making this technology economically viable. [ABSTRACT FROM AUTHOR]

In this article, the authors conduct a study of bending effects of a paper‐based printed antenna in order to predict the behavior of an antenna placed inside a package with restricted dimensions. The study begins with a model of an electrical dipole consisting of two misaligned parts to evaluate qualitatively the effect of the angle between two parts and the proportion of their lengths on the radiation properties of the dipole. In order to validate the theoretical prediction, a wide‐band "mushroom‐shaped with two arms" monopole antenna structure printed on 0.104 mm thick paper is proposed. This antenna covers a very wide frequency range from 1.8 GHz to over 10 GHz, including two WLAN bands. Its radiation patterns are nearly omni‐directional at 2.45 and 5.5 GHz. The study of substrate bending effects shows that the matching properties of the antenna are maintained, but the antenna radiation patterns are rotated by an angle with respect to the case without bending. The results of our study can be used to predict the performance of an antenna when it is deformed in a telecommunication set‐top box with restricted dimensions. [ABSTRACT FROM AUTHOR]

A compact 2-element antenna for MIMO applications with performance across the WLAN frequency bands is designed and fabricated on paper with a FUJI Film Dimatix 2800 material printer and conductive ink. This antenna is ∼1.1 cm × 3.5 cm and utilizes co-planar feeding techniques and ground design to allow for resonance in the 2.4 and 5 GHz frequency bands with a minimum 800-MHz bandwidth. The design is established using commercially available products for minimal processing. Factors such as ink handling, printing conditions, and paper selection are discussed qualitatively as they relate to antenna fabrication and performance. Successful simulation and fabrication is reported with low correlation, high isolation, and low reflection. [ABSTRACT FROM AUTHOR]

This letter presents a new technique to fabricate aperture type cylindrical frequency selective surface (FSS) with circular, tripole, and plus shaped element. The cylindrical FSSs exhibit band pass property from 5 to 9 GHz, 11.75 to 14.75 GHz, and 7 to 14 GHz, respectively. A novel method with aluminium foil paper is suggested for fabrication. Cylindrical FSS is fabricated with this technique in laboratory with commercially available aluminium foil paper and is measured practically. In this technique, with the help of laser cutting machine 0.01 mm precision label can be achieved. Both simulated and measured results are in good agreement. The aluminium foil paper made FSS proved to be very light weight, flexible and low cost. [ABSTRACT FROM AUTHOR]

Abstract: A wide band flexible substrate based metamaterial is presented. The metamaterial is fabricated on photo paper using conductive nanoparticle ink targeting flexibility applications. The metamaterial structure shows a wide double negative region of 1.848 GHz (8.298–10.146 GHz). The transmission coefficient of the proposed metamaterial has been measured and verified with simulated one. The perceptible novelties of the proposed work are its simplicity, cost effectiveness, and flexibility with covering wide X‐band microwave spectra. [ABSTRACT FROM AUTHOR]

ABSTRACT Two key components, among several, in the design of a conformal antenna are the planar conductors and the flexible substrates. In this paper, a new approach of using graphene-based conductors instead of copper conductors in the design of a conformal antenna is presented. To determine the conductivity properties of the graphene-based conductor, the copper conductors in a well-known micro-strip transmission line (TL) and micro-strip antenna were replaced with the graphene-based conductors and were analytically evaluated, simulated in a full-wave simulation software and experimentally tested. Overall, it was shown that these graphene-based conductors have a conductivity that is high enough to design a useful micro-strip TL and micro-strip antenna. In particular, a conductivity of σ = 1.94 × [ABSTRACT FROM AUTHOR]

ABSTRACT A significant cost in the widespread deployment of UHF radio frequency identification (RFID) systems has been the passive RFID tags. To address some of this expense, this paper presents an antenna design for UHF RFID tags that can be printed on inexpensive paper substrates and operate in the near field of the UHF reader. This antenna design is based on meander line miniaturization techniques and open complementary split ring resonator (OCSRR) elements to reduce the amount of conducting material required to manufacture the antenna by 30%. For demonstration purposes, a prototype near-field UHF RFID tag was manufactured on a paper substrate and the read-range was measured at 920 MHz. It was shown that useful read-ranges could be achieved while reducing the overall cost and size of the antenna on the RFID tag. © 2017 Wiley Periodicals, Inc. Microwave Opt Technol Lett 59:1052-1056, 2017 [ABSTRACT FROM AUTHOR]

ABSTRACT A pattern-switchable origami antenna is designed with paper using inkjet-printing technology. The proposed antenna can be switched between loop and dipole antenna modes by folding and unfolding the paper, respectively. Eutectic gallium-indium liquid metal is introduced in order to avoid cracks in the conductive ink when the paper is folded. The performance of the proposed antenna is demonstrated through simulation and measurement results. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:668-672, 2016 [ABSTRACT FROM AUTHOR]

ABSTRACT This article presents the design, manufacturing, and measurements of antennas on paper, realized using ink-jet printing of conductive inks based on nano-silver particles (nSPs). The extraction of the substrate characteristics such as the dielectric constant and dielectric loss is performed using a printed ring resonator technique. The characterization of the nSPs conductive inks assesses different parameters as sintering time and temperature. Two antennas are realized corresponding to the most common needs for wireless sensor networks in Trains Environment. The first one is a patch antenna characterized by a broadside radiation pattern and suited for operation on metallic structures. The second one is a quasi-yagi antenna, with an end fire radiation pattern and higher directivity, without requiring a metallic ground plane. Both antennas present a good matching ( S11 < −20 dB and S11 < −30 dB, respectively) and acceptable efficiency (55% and 45%, respectively) for the paper substrate used at the center frequency of 2.4 GHz, corresponding to the first channel of the IEEE 802.15.4 band. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:754-759, 2016 [ABSTRACT FROM AUTHOR]

The letter presents the design, fabrication, and measurement of a configurable radio frequency identification (RFID) tag based on time-domain reflections. The tag circuit contains a microstrip line (ML) that propagates radio frequency (RF) signals, and a group of capacitors that introduce impedance discontinuities to encode binary codes. The configurability of the tag circuit is allowed by connecting the nearby-placed capacitors with the ML. Ink-jet printing technology is employed to implement the layout of the proposed tag on paper substrate. To overcome the limitations of printed metallic tracks, a linearly tapering technique is proposed. With this technique, a four-bit configurable passive chipless RFID tag is realized. Both time-domain reflectometry (TDR) measurements and ultrawideband (UWB) characterizations were conducted for the proposed tag, and the results are in good consistence with the simulation ones from the circuit simulator advanced design system (ADS). Owing to its low cost fabrication and environmentally friendly nature, the proposed tag has great potential to be widely employed in low-end RFID applications. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:2781-2786, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26412 [ABSTRACT FROM AUTHOR]

Stimulated by an injected continuous wave, a set of longitudinal modes wins the competition for gain medium continuously. In this paper, the linewidth of the longitudinal mode is broadened by the injected continuous wave. The wavelength of an actively mode-locked fiber laser based on EDFA is stabilized in the experiment. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 1385–1388, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21645 [ABSTRACT FROM AUTHOR]

This paper presents a novel technique to evaluate OSNR using asynchronous histograms. The technique is based on a comparison between a numerically estimated asynchronous histogram of the signal to be measured and the monitored signal. Experimental validation of proposed technique is presented. Measurement errors below 1 dB are achieved for OSNR values below 32 dB. The proposed technique is also validated for cases where the monitored signal presents significant dispersion-induced distortion, without presenting significant loss of accuracy. The principal limitations of the proposed technique are also investigated. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 1369–1372, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21648 [ABSTRACT FROM AUTHOR]

Significant research and development in the areas of microwave photonics in Brazil are presented in this paper. These include direct microwave modulation of semiconductor laser diodes, optical control of MESFETs and HEMTs as well as high speed fiber optic components. Future directions for research in this area are discussed. [ABSTRACT FROM AUTHOR]

We systematically analyze the mode-coupling effects of stress-induced long-period gratings (LPGs) using photonic crystal fiber (PCF). Two Mach–Zehnder interferometers based on this grating are demonstrated. These devices offer the unique advantages of being tunable and reconfigurable. Their good interfering efficiency makes them promising for wavelength-selective filters in WDM communication systems. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 1379–1383, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21647 [ABSTRACT FROM AUTHOR]

A method to extract the elements of the small-signal equivalent circuit and the noise parameters (NPs) of heterojunction bipolar transistors (HBTs) is presented. The extraction is done by simultaneous fitting of the measured S-parameters, noise figure (for a well-matched impedance), and NPs (estimated using the so-called F50 method). An additional error term, given by the root square sum of the differences between the NPs estimated from the F50 method and the NPs directly computed using the Hawkins model, is considered in order to avoid nonphysical results in the extraction of the intrinsic noise sources. To obtain the initial values of the equivalent-circuit elements, analytical expressions are applied under a number of bias conditions, namely, reverse bias, forward bias, and active bias. Experimental verification of the extraction of the equivalent-circuit elements and NPs of an HBT, up to 8 GHz, are presented, and the NPs are compared to those measured with an independent (tuner-based) method. The behavior of Fmin, extracted using the proposed method, as a function of the HBT collector current, is also presented. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 1372–1379, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21649 [ABSTRACT FROM AUTHOR]

A compact dual-WLAN-band antenna, in the shape of a paper clip, is presented. The antenna can be easily manufactured by bending few times a single copper wire with a length of about 65 mm, and it operates in the 2.4 and 5.2 GHz bands in the WLAN environment. In addition to the simple configuration, the antenna is easily fed by a 50-Ω mini-coaxial cable which allows it to be flexible in a defined location for installation. An experimental prototype of the proposed antenna with the overall dimensions of about 5 mm × 23.5 mm is constructed, tested, and demonstrated. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2572–2574, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23760 [ABSTRACT FROM AUTHOR]

Moreover, they are particularly grateful to the authors of all the submitted papers for their efforts and contributions to this Special Issue, and to the reviewers for devoting their valuable time and expertise to review the submitted manuscripts. Authors of the accepted and presented papers during the iWEM 2021 were invited to submit expanded versions of their conference papers in this special issue. This special issue of Microwave and Optical Technology Letters (MOTL) includes nine expanded papers from the 2021 IEEE International Workshop on Electromagnetic: Applications and Student Innovation Competition (IEEE iWEM2021). [Extracted from the article]

This paper presents a 4th-order accurate implicit multistage finite-difference time-domain (IMS-FDTD) method. The analysis of the stability shows that this IMS-FDTD method is unconditionally stable. In addition, its numerical-dispersion relation is derived and the analysis shows that its performance is better than those of conventional unconditionally-stable implicit FDTD methods and is even better than those of some conditionally-stable explicit FDTD methods, such as the Fang(2, 4)-FDTD method. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 1383–1385, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21646 [ABSTRACT FROM AUTHOR]

Vertex plates are commonly used to improve the return loss of primary-fed reflector antennas. We propose a new type of vertex plate with a Gaussian thickness profile that gives lower far-out sidelobes of the radiation pattern of the reflector antenna than the standard vertex plate with constant thickness. We derive the dimensions of this vertex plate needed to cancel the field at the focus of the reflector. We apply the design rules to improve the return loss (RL) of a primary-fed reflector with hat feed, and simulate it by using a computer code based on the finite-difference time-domain (FDTD) technique. The results verify the improvements of the radiation pattern obtained by using a Gaussian vertex plate rather than a standard one. ©1999 John Wiley & Sons, Inc. Microwave Opt Technol Lett 21: 125–129, 1999. [ABSTRACT FROM AUTHOR]