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In order to encrypt/encode data based on the magnitude level of the radar cross-section (RCS), we propose an approach with a precise estimation considering the resonant characteristics of a multipatch backscatter-based chipless radio frequency identification (RFID) dedicated for chipless tags depolarization. The working principle is based on the polarization mismatch between the tag and the reader antenna to control the magnitude of the backscatter, which allows a reliable detection in real environments. We introduce in this paper a new 4-bit chipless RFID tag with an enhanced RCS, based on a triangular patch antenna with multiple resonators. Additionally, we propose an ultra-wideband impulse radar (UWB-IR)-based reader that interrogates the chipless tag with a UWB pulse, and the received backscatter was studied in both time- and frequency-domains. The antenna was operating from 4.7 to 6.1 GHz, a band allocated for RFID systems. The obtained experimental measurement results in the environment of anechoic chamber were exceptionally relevant to validate the simulation results. [ABSTRACT FROM AUTHOR]

We investigate wave motion in a continuous elastic rod with a periodically attached inertial-amplification mechanism. The mechanism has properties similar to an "inerter" typically used in vehicle suspensions, however here it is constructed and utilized in a manner that alters the intrinsic properties of a continuous structure. The elastodynamic band structure of the hybrid rod-mechanism structure yields band gaps that are exceedingly wide and deep when compared to what can be obtained using standard local resonators, while still being low in frequency. With this concept, a large band gap may be realized with as much as twenty times less added mass compared to what is needed in a standard local resonator configuration. The emerging inertially enhanced continuous structure also exhibits unique qualitative features in its dispersion curves. These include the existence of a characteristic double-peak in the attenuation constant profile within gaps and the possibility of coalescence of two neighbouring gaps creating a large contiguous gap. [ABSTRACT FROM AUTHOR]

In this paper, a novel design of high roll‐off frequency selective surface (FSS) is proposed based on a single‐layer substrate integrated waveguide (SIW) cavity. Fully canonical filtering responses with three transmission poles (TPs) and three transmission zeros (TZs) are obtained by employing transversal signal‐interference techniques (TSITs). The FSS unit cell can be regarded as a combined triple‐mode cavity consisting of one cross‐slot resonator and two SIW cavities. By using the filtering coupling matrix, the FSS can be well designed and analysed. Accordingly, to verify the design concept, a prototype is fabricated and experimented. Measured and simulated results are in good agreement, showing high performances in terms of high roll‐off and low profile. [ABSTRACT FROM AUTHOR]

Hyperbolic metamaterials were initially proposed in optics to boost radiation efficiencies of quantum emitters. Adopting this concept for antenna design allows approaching long-standing contests in radio physics. For example, broadband impedance matching, accompanied with moderately high antenna gain, is among the existent challenges. Here we propose employing hyperbolic metamaterials for a broadband impedance matching, while a structured layer on top of a metamaterials slab ensures an efficient and directive energy outcoupling to a free space. In particular, a subwavelength loop antenna, placed underneath the matching layer, efficiently excites bulk metamaterial modes, which have well-resolved spatial–temporal separation owing to the hypebolicity of effective permeability tensor. Interplaying chromatic and modal dispersions enable to map different frequencies into non overlapping spatial locations within a compact subwavelength hyperbolic slab. The outcoupling of energy to the free space is obtained by patterning the slab with additional resonant elements, e.g. high index dielectric spheres. As the result, two-order of magnitude improvement in linear gain of the device is predicted. The proposed new architecture can find a use in applications, where multiband or broadband compact devices are required. [ABSTRACT FROM AUTHOR]

Wearable sensors promise to transform human understanding of body state. However, despite many wearable sensor modalities that exist, few demonstrate the raw capabilities required for many emerging healthcare applications—passivity (and microelectronics‐free), wireless readout, long‐term operation, and specificity. Hydrogel‐interlayer radio‐frequency resonators are demonstrated as a versatile platform for passive and wireless biosensing. Fabricated using a simple vinyl cutter, the base resonator is composed of unanchored, broad‐side coupled coils interceded by multifunctional hydrogels—such resonators are tuned to be sensitive to specific analytical or physical signals by modifying hydrogel composition. These resonators are transformed into near‐field communication (NFC) sensor circuits through the simple attachment of an LED. These enable direct quantification of sensor state by cellphone and eye with no specialized electronics required. Resonator arrays are finally fused with silicone to form soft, wireless sensor skins that enable co‐readout of analytical to physical signals while molded to human subjects. Such low‐cost, accessible platforms can integrate with environments in transformative ways, enabling new applications in wireless sensing. [ABSTRACT FROM AUTHOR]

Radio frequency (RF) probes for ultrahigh-field magnetic resonance imaging (MRI) systems were developed from structures inspired by microstrip patch antennas. The patch structures provide an alternative to conventional surface coils. We show that these structures, operating as resonators, can produce strong magnetic fields, which act as B1 fields in MRI studies. The addition of high permittivity inserts to the patch substrate was beneficial for increasing B1 field uniformity. It was also shown by simulations that two vis-à-vis placed identical patches fed with 180° phase difference could produce uniform B1 field in the space between patches and could be used as volume RF probes. This possibility was confirmed by experiments with fabricated prototypes in the VARIAN 14.1 T MRI scanner. We further show that the B1 uniformity is enhanced over larger volume with properly profiled substrates of higher permittivity, along with smaller radiation losses. These probes were found competitive and even advantageous in comparison with birdcage coils because of better stability of their Q-factors at loading by lossy phantoms. Thus, patch-based probes offer a viable alternative to RF probes for ultrahigh field MRI. [ABSTRACT FROM AUTHOR]

This work illustrates a novel design of metamaterial inspired structure on miniaturization of microstrip patch antenna. The proposed structure consists of a hexagonal microstrip patch antenna loaded with two hexagonal complementary split ring resonator unit cells etched in the ground plane along with a shortening pin. The proposed dualband antenna with resonances at 3.394 GHz and 4.852 GHz possess the advantages of having simple and miniaturized structure, good impedance matching and VSWR with very low return loss at both resonances. The overall dimension of the proposed antenna is 0.22λ0 x 0.22λ0. Also, the electromagnetic characteristics of the resulting composite medium were evaluated from the simulated complex scattering parameters to demonstrate the extant of metamaterial. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, a novel dual wideband microstrip bandpass filter is proposed. The designed filter is constructed by two different stub loaded resonators located at the upper and bottom sides of the coupling line. The coupling transmission line is also connected to input and output (IO) ports. The upper resonator creates a wide passband, whereas the bottom resonator is used to create two transmission zeros in the passband. Thus, a wide passband can be divided into dual wide passbands. The bottom resonator is also utilized to improve the insertion and return losses in the passband. The designed filter is fabricated and tested in a very good agreement with the simulated results. The measured fractional bandwidths (FBWs) of the passbands are 44.6% and 24.2% at the center frequencies of 3.4 GHz and 5.51 GHz, respectively. The measured insertion losses in the passbands are 0.51 dB and 1.13 dB. [ABSTRACT FROM AUTHOR]

Robustness evaluation is a critical part to verify the applicability of wireless implantable devices. In this work, we present a semi-anatomical ellipsoid head model to evaluate the robustness of a split ring resonator inspired antenna system toward variable implant location, tissue layer thicknesses, and antenna orientation with respect to the human head. The system consists of a passive wearable part placed on the scalp and a cortical implant that carries a passive UHF RFID microsystem. According to our results, the antenna system is robust toward variability: it enables the remote powering of a -18 dBm RFID microsystem at distance between 0.5 and 1.1 meter at various locations and orientations with respect to the head and for skull thickness up to 1 cm. [ABSTRACT FROM AUTHOR]

An aperture coupled rectangular dielectric resonator antenna (RDRA) is proposed where high permittivity radiating element is embedded on a comparatively low permittivity secondary substrate material (here FR4 is used). Proposed dielectric resonator antenna (DRA) is accurately excited in fundamental mode TElu for efficient broadside radiation. All the existing DRAs are placed on ground plane using adhesive which is not suitable for practical application. The proposed design can be considered as a promising solution of mounting of DRA on the ground plane with good mechanical firmness. Since the RDRA is embedded on FR4 substrate, it can be withstand very high pressure and vibrating condition which is the main practical limitation of existing DRA technology. The effect of embedding the radiating DRA on secondary substrate is studied here in details. A prototype of single antenna element is designed, fabricated and measured to validate the simulation results. Further, a 2 x 2 antenna array with such antenna element is designed at the center frequency of 6.684 GHz for obtaining higher directive gain. The array offers an impedance bandwidth of 4.94% and a maximum gain of 13.4 dBi at the operating frequency. A good agreement has been obtained between the measured and simulated results. [ABSTRACT FROM AUTHOR]

Summary: A new geometry of compact meta‐surface, loaded with the ring resonator for satellite application (Ku‐band), is presented in this paper. The diamond‐shaped meta‐surface is designed by the metallic ring resonator with metallic ground plane separated by a dielectric substrate layer, while epoxy resin fibre is utilized as a dielectric substrate layer. The proposed meta‐surface structure is successfully simulated, fabricated, and measured. Effects of the design specifications on the surface current and field distribution are also investigated elaborately. Theoretical and simulated results show that the diamond‐shape structure resonance is at 15.84 GHz, whereas the measured results are slightly shifted around at 15.87 GHz. The designed meta‐surface structure also exhibits the left‐handed characteristics at 15.88 GHz, where the estimations of permittivity is −4 + 0.28j, permeability is −19.2 − 134.6j, and negative index is −5.51 − 3.86j. Further, the lumped element equivalent circuit model of the proposed meta‐surface unit cell is explained. Moreover, the 10 × 10 mm2 meta‐surface single‐unit‐cell prototype is compact in size and the impact on the performance by modifying the meta‐surface structure is investigated. Therefore, the meta‐surface integrated antenna shows resonance frequency bands from 14.0 to 14.50 GHz, which is used as INSAT‐4A communication satellite uplink frequency. [ABSTRACT FROM AUTHOR]

Summary: Ever increasing bandwidth requirements in satellite communications continuously push the frequency limits. Q‐ band (33 – 50 GHz) is the next frequency band to be populated; however, at these frequencies, the Earth's troposphere (weather) profoundly alters the radio propagation conditions. Therefore, in order to properly plan radio links, accurate statistical models of radio channels are necessary. These statistical models are built upon empirical data, ie, measurements, which are furthermore used to design appropriate Propagation Impairment Mitigation Techniques. The Q‐ band lacks such data, hence the statistical models are inadequate. To address this problem, we propose a cost‐effective, easy to replicate Q‐ band beacon receiver to leverage the Alphasat propagation campaign. We present a step‐by‐step implementation process of the receiver's fundamental part, a Low‐Noise Block, which translates input 39.402 GHz signal into 162 MHz output signal with a conversion gain of 52 dB. The receiver furthermore utilizes software define radio for signal processing and other data manipulation. Here, we describe the receiver implementations in great details, supplementing the crucial parts with laboratory validation results. Finally, we show 2 example datasets, showing usual data obtained during heavy showers and on a quiet day, respectively. [ABSTRACT FROM AUTHOR]

Summary: In this paper, a practical non‐linear equalizer with iterative distortion cancellation in a satellite receiver is studied. Assuming no prior satellite channel knowledge, distortion estimation and cancellation are performed at the receiver by means of a memory polynomial model used for channel estimation. A data packet transmission scenario over a single‐carrier satellite transponder is simulated, using the not‐linearized amplifier and onboard filter characteristics similar to the direct‐to‐home broadcast DVB‐S2X reference scenario. Varying the memory depth and the non‐linear order of the memory polynomial model trained in the receiver, we compared the packet‐error rate performance of the practical non‐linear equalizer to the standard fractionally spaced linear adaptive equalizer, as well as to an implementation of the non‐linear equalizer with ideal channel knowledge at the receiver. The improved receiver demonstrates superior performance as compared with the standard linear equalizer with up to 5.48‐dB energy efficiency gain for 64‐amplitude and phase‐shift keying for a practical memory polynomial set‐up, and it approaches consistently the packet‐error rate performance of the implementation with ideal channel knowledge when increasing the memory depth and the non‐linear order. Furthermore, it enables the use of high‐order modulation up to 256‐amplitude and phase‐shift keying in the studied scenario, improving significantly the spectral efficiency of the air interface. [ABSTRACT FROM AUTHOR]

In this paper, a general design method for multiband filters is proposed. First, the frequency and element transformations from a low-pass prototype filter to a practical multiband bandpass filter is derived. Afterwards, formulas for extracting the coupling coefficient $k$ between coupled multimode resonators and the external quality factor $Q_{e}$ are also obtained. Thereafter, the design procedure of coupled multiresonator multiband filters is similar to that of single-band filters. A tri-band microstrip filter with tri-mode resonators is successfully designed with the proposed method and fabricated, which validates this theory. [ABSTRACT FROM AUTHOR]

Objective: The objectives of this study were to design and develop an open-circuit electromagnetic resonant skin patch sensor, characterize the fluid volume and resonant frequency relationship, and investigate the sensor's ability to measure limb hemodynamics and pulse volume waveform features. Methods: The skin patch was designed from an open-circuit electromagnetic resonant sensor comprised of a single baseline trace of copper configured into a square planar spiral which had a self-resonating response when excited by an external radio frequency sweep. Using a human arm phantom with a realistic vascular network, the sensor's performance to measure limb hemodynamics was evaluated. Results: The sensor was able to measure pulsatile blood flow which registered as shifts in the sensor's resonant frequencies. The time-varying waveform pattern of the resonant frequency displayed a systolic upstroke, a systolic peak, a dicrotic notch, and a diastolic down stroke. The resonant frequency waveform features and peak systolic time were validated against ultrasound pulse wave Doppler. A statistical correlation analysis revealed a strong correlation (R^2\,= \,0.99 ) between the resonant sensor peak systolic time and the pulse wave Doppler peak systolic time. Conclusion: The sensor was able to detect pulsatile flow, identify hemodynamic waveform features, and measure heart rate with 98% accuracy. Significance: The open-circuit resonant sensor design leverages the architecture of a thin planar spiral which is passive (does not require batteries), robust and lightweight (does not have electrical components or electrical connections), and may be able to wirelessly monitor cardiovascular health and limb hemodynamics. [ABSTRACT FROM PUBLISHER]

This research article proposes a highly dense, inexpensive, flexible and compact 29 x 29 mm2 chipless radio frequency identification (RFID) tag. The tag has a 38-bit data capacity, which indicates that it has the ability to label 238 number of different objects. The proposed RFID tag has a bar-shape slot/resonator based structure, which is energized by dual-polarized electromagnetic (EM) waves. Thus, portraying polarization insensitive nature of the tag. The radar cross-section (RCS) response of the proposed tag design is analyzed using different substrates, i.e., Rogers RT/duroid®/5880, Taconic (TLX-0), and Kapton®HN (DuPontTM). A comparative analysis is done, which reveal the changes observed in the RCS curve, as a result of using different substrates and radiators. Moreover, the effect on the RCS response of the tag is also examined, by bending the tag at different bent radii. The compactness and flexible nature of the tag makes it the best choice for Internet of things (IoT) based smart monitoring applications. [ABSTRACT FROM AUTHOR]

This communication presents the design of an ultra-wideband antipodal tapered slot antenna (ATSA) with frequency notch characteristics. Subwavelength resonators in the form of square split-ring resonators are placed on the aperture as well as on the feed section of the ATSA to invoke the frequency notches. The electromagnetic coupling of the SRRs with the radiating aperture and with the magnetic fields due to the fringing at the microstrip line feed yields the frequency notches. The invoked notches are sharp in comparison with previously reported designs. The fabricated prototypes were experimentally verified through measurements, and a good agreement with simulations was obtained. The impedance and radiation plots confirm the suppression of the desired notch frequency. A theoretical formulation to calculate the notch frequency is also proposed and validated. [ABSTRACT FROM PUBLISHER]

In this paper, a compact lowpass filter (LPF) with ultra-wide rejection band has been presented. In fact, a novel meandered semi-hairpin resonator has been used and the stopband characteristics have been improved by using a combinatorial suppressing unit. The suppressing unit contains a combination between T-shaped and semi-circular patches, which are loaded symmetrically to the designed resonator. For the proposed LPF, the-3 dB cut-off frequency has been adjusted to 2.2 GHz. After simulations, the proposed LPF has been fabricated and tested. The experimental results validated that the rejection bandwidth is expanded from 2.471 GHz to 28.62 GHz with corresponding attenuation level of −20 dB. The transition band is only 0.271 GHz from 2.2 GHz to 2.471 GHz with corresponding attenuation levels of −3 dB to −20 dB, respectively. In addition, the measured maximum insertion loss and return loss in the passband, from DC to 2.04 GHz (93% of the passband region) are 0.2 dB and 17 dB, respectively. [ABSTRACT FROM AUTHOR]

In this paper, we investigate the propagation of high-frequency current waves along a stochastic transmission line inside a rectangular cavity using as basis the model of a transmission line with the symmetry of the resonator. The stochastization of the line is created by a stochastically arranged chain of loads. Using similar models one also can take into account stochastic geometry of the line. Research has shown a significant difference between the propagation of the current wave along the transmission line with stochastic loads in free space and in the resonator. In the first case, the average square of the absolute value of the transmission coefficient exponentially tends to zero with increasing length of the line due to interference phenomena for current waves. In the second case, in the average, the current can penetrate through the stochastic chain of the loads due to the re-reflection of the signal from the walls of the resonator. [ABSTRACT FROM AUTHOR]

A multi-functional microstrip-fed ultrawideband (UWB) monopole antenna has been presented. By loading two dual-mode resonators and shunt metallic strips on the reference UWB antenna, two additional operational states are created, including band-notched UWB response (i.e., 3.1~11.5 GHz passband response except the notched band of 5.15~5.8 GHz) and narrow bandpass response (5.5-5.95 GHz) with high frequency selectivity. Moreover, the frequency characteristics of bandpass filtering antenna is also studied when we solder two lumped-chip 0 Ω resistors instead of the shunt metallic strips. Four antenna prototypes are designed, fabricated and measured to validate the design concept. Full-wave electromagnetic simulator HFSS is used for the antenna design optimization and performance prediction. The measured results are presented including return losses, gains and radiation patterns, declaring that the proposed antennas have good impedance matching performance and radiation patterns. [ABSTRACT FROM AUTHOR]

This paper presents a simple generalized approach to design a compact chipless radio frequency identification tag. The proposed chipless tag encodes data into the spectral signature using a set of spiral resonators on both sides o f substrate. Transmission amplitude component of the tag is used for data encoding. For miniaturization purpose, defected ground structure is used to reduce the circuit size by half compared to the conventional cascading technique. The proposed chipless tag operates between 4 GHz and 6 GHz and produces 256 different binary strings through eight encoded bits. Measurement and simulation results verify the authenticity of this design. [ABSTRACT FROM AUTHOR]

This paper presents a compact, wideband, waveguide bandpass filter using a hybrid combination of complementary split ring resonators (CSRRs) and Koch fractal. Three identical planar structures, printed with CSRRs and Koch fractal, have been placed in the transverse plane of a standard WR-90 waveguide at a quarter wavelength distance to form the filter. The proposed filter has been simulated using Ansoft HFSS (version 14) and the obtained frequency response has been compared with the frequency response of its lumped element equivalent circuit. The filter was also fabricated and its frequency response has been measured. The measured result shows a 3-dB fractional bandwidth of 12.66% at resonant frequency 9.95 GHz. The total length of the fabricated filter is 20.33 mm. Detailed design procedure has been presented along with necessary diagrams. A table has been provided to compare the performance of the proposed filter with those already available in the literatures. The table shows that the proposed filter is compact, has higher bandwidth and better frequency response compared to the rests. [ABSTRACT FROM AUTHOR]

In this article, a cylindrical dielectric resonator antenna (CDRA) excited by a 45° rotated square ring slot with a T-shaped coupling microstrip line is investigated for circularly polarized (CP) operation. The proposed antenna shows the dual band characteristics and the lower band is generated due to T-Shaped microstrip line and upper band is due to CDRA. In the proposed antenna, the two degenerate broadside orthogonal modes ( [ABSTRACT FROM AUTHOR]

This letter presents a whole UWB band suppressed ring resonator bandpass filter with small LUCs (Lowpass filter unit cells) [Lee W-K, Hwang H-Y. J Electromagn Eng Sci. 2014;14:387-392.] based on artificial transmission lines [Martin F. Artificial Transmission Lines for RF and Microwave Applications. 1st ed. New York: Wiley; 2015]. Two LUCs are used as building blocks for miniaturization and harmonic suppression of the ring resonator of the filter. Design equations for proper characteristic impedances of the ring and for proper stopband transmission zeros of the LUCs are newly presented. Fabricated filter shows insertion loss of 2.3 dB at center frequency of 2.55 GHz, fractional bandwidth of 2.5%, and good harmonic suppression about 20 dB in whole ultra-wide band, which agreed well with the simulation results. The ring area of the proposed bandpass filter has 36% of that of the conventional one. [ABSTRACT FROM AUTHOR]

An frequency selective surface (FSS) structure based on parallel LC resonators is proposed to achieve multiband bandpass filtering responses. The parallel LC resonator, implemented by a via-connected metallic line and a parallel-plate capacitor (PPC), serves as the basic element for intentionally constructing FSS unit cell, which exhibits a single-band bandpass filtering response. As a result, the proposed FSS structure can provide a multiband performance by introducing multiple VCMLs and PPCs with different resonance frequencies. Because of the compact resonator resulting from a PPC, the proposed FSSs feature miniaturized unit cell size inherently, for example, the single-band FSS element is as compact as 4.8% of the operating wavelength. Moreover, this kind of FSS structure is also beneficial for independent control of the frequency performance under different polarizations, efficient optimal design of desired resonance frequencies, and easy realization of multiband response with wideband ratio range (e.g., 1.13 to 3.32 for the dual-band FSS). Equivalent circuits of these FSSs are established for explaining the resonating mechanisms and precisely modeling the frequency performances. Finally, prototypes of the dual- and tri-band FSSs are fabricated and measured. The measured results exhibit stable filtering performance under different polarizations and incidence angles (up to 60°). [ABSTRACT FROM PUBLISHER]

A helical resonator with two-sectional different pitches is proposed in this paper. The frequency ratios of the first two resonant modes of the helical resonator can be tuned to desirable values in a certain range by adjusting the pitches. The proposed resonator is applied to design dual-band bandpass helical filters. To achieve control over dual-band filtering characteristics, a feeding structure with step-rectangular plate and a coupling window with three apertures are also proposed to realize the expected external quality factors and coupling coefficients in the two bands. To validate the design, a second order and a fourth order dual-band helical filters are fabricated and measured. The measured results show good agreement with simulation ones. [ABSTRACT FROM AUTHOR]

The non-linear behaviour of the superconducting microstrip open-ring resonators is computed by an analytical method based on the distributed equivalent circuit model of transmission lines. In fact, the equivalent circuit model of the openring resonator is analysed and relative non-linearities such as third-order harmonic generation and third-order inter-modulation (IMD3) distortion, are computed by the harmonic balance approach. As an example, the method is applied to a superconducting open-ring resonator and its IMD3 is obtained and compared with experiment to validate the accuracy of the proposed method. Such approach can considerably save time, cost and memory usage of the simulation and experiments. [ABSTRACT FROM AUTHOR]

Hybrid encoding technique is an efficient method to expand the coding capacity in radio-frequency identification chipless tag design. In this study, a novel hybrid coding technique by combining amplitude deviation and frequency position encoding is proposed. The proposed tag is based on three circle ring resonators with loaded resistors. A transmission line model is employed to illustrate the operation principle of the impedance loading technique. A coding capacity of at least 23.7 bits is obtained within a compacted dimension of 3 cm × 3 cm. Corresponding experiments on realised prototypes are provided to validate the effectiveness of the proposed design. [ABSTRACT FROM AUTHOR]

A simple tri-band monopole filtering antenna using multimode resonators is proposed. Two novel microstrip open-loop multimode resonators and a monopole ring antenna with an open stub are integrated together on the same layer of the substrate. Compared with the traditional monopole antenna, the integration makes the proposed antenna operate at 2.4/5.2/6.5 GHz and realize two radiation zeroes at 2 and 3.3 GHz. It leads to the high selectivity for 2.4 GHz. The measured results, including the reflection coefficient, peak realized gain and radiation pattern agree well with the simulated results. [ABSTRACT FROM AUTHOR]

The use of complementary split-ring resonators (CSRRs) as radiating elements in low-profile on-metal ultra-highfrequency radio-frequency identification (UHF-RFID) tags is explored in this study. First, the radiation properties of the edgecoupled and the non-bianisotropic (NB-CSRR) versions of the CSRR are studied. The tag design strategy is then discussed in detail. On that basis, a compact (λ0/7 x λ0/7) low-profile (1.27 mm) tag prototype based on the non-bianisotropic version of the CSRR (NB-CSRR) antenna is designed and manufactured to operate in the North-American UHF-RFID band. The experimental results validate the theoretical and simulated behaviour, and exhibit a maximum read range of 6.8 m. [ABSTRACT FROM AUTHOR]

ABSTRACT The aim of this work is to design a low-profile Circularly Polarized Dielectric Resonator Antenna for the X-band frequency applications. With optimized design the proposed Cylindrical DRA (CDRA) fed by off-centered L shaped slot is showing characteristics of Circular Polarization in the proposed band. Two orthogonal arms of off-centered L shaped slot having different dimension excite the two TM01δ modes at 9.5 and 10.5 GHz, in addition both slots itself produce resonances nearly at 8.6 GHz. Combination of all these resonances is generating the nature of circular polarization near 9.5 GHz. Parametric study on designed antenna has been done in order to determine the effect of design parameters on the circular polarization. Axial Ratio bandwidth of 10.5% (1 GHz) and impedance bandwidth of 25% (2.3 GHz) at 9.5 GHz has been shown for single and simple feed low-profile CDRA. Prototype of optimized design has been fabricated for the validation and measured results have shown good agreement with simulated ones. © 2017 Wiley Periodicals, Inc. Microwave Opt Technol Lett 59:996-1000, 2017 [ABSTRACT FROM AUTHOR]

The Split ring resonator [SRR] loaded Pythagoras tree fractal antenna frequency band applications are presented. The CPW- Fed antenna consists of SSRR which is fixed on the reverse side of the substrate and iterated Pythagoras which is printed on top of the FR4. the Pythagoras fractal tree SRR antenna with a compacted size of 16 x 14 mm2 is fabricated and tested. The multiple frequency for antenna measured yields with a -10 dB in 1.98/ 4.18/ 5.92/ 7.92/ 11.02/ 13.92/ 15.98/ 19.06 GHz ban and cover up the frequency spectrum of GSM, WiMAX, IEEE 802.11a (WLAN)/b/g, IEEE 802.16e, ITU, s/c/x/ku and K band, correspondingly. The extraction method of-ve permeability for the proposed square spilit resonator is examined in detail. The antenna proposed have a significant reward,including low profile, miniaturization capability with good S11 and VSWR. Radiation pattern with a standard antenna gain of 2.46 dBi is observed for the functioning bands. [ABSTRACT FROM AUTHOR]

The design of a three-port radiating structure, integrating wide and narrow band antennas for cognitive radio applications, is presented. It consists of a UWB antenna for spectrum sensing and two narrow band antennas for wireless communication integrated on the same substrate. The UWB antenna covers the complete UWB spectrum (3.1 GHz to 10.6 GHz) approved by FCC. In the two narrow band antennas, each antenna presents dual bands. In particular, the first narrowband antenna resonates at 6.5 GHz, covering the frequency band between 6.36 GHz and 6.63 GHz, and at 9 GHz, covering the frequency band between 8.78 GHz and 9.23 GHz, presenting minimum return loss values of 28.3 dB at 6.5 GHz and 20.5 dB at 9 GHz, respectively. Similarly, the second one resonates at 7.5 GHz, covering the frequency band between 7.33 GHz and 7.7 GHz, and at 9.5 GHz, covering the frequency band between 9.23 GHz and 9.82 GHz, presenting minimum return loss values of 19.6 dB at 7.5 GHz and 28.8 dB at 9.5 GHz, respectively. Isolation among the three antennas is less than −20 dB over the UWB frequency spectrum. These antennas are realized on a FR4 substrate of dimensions 30 mm × 30 mm × 1.6 mm. Experimental results show a good agreement between the simulated and measured results. [ABSTRACT FROM AUTHOR]

A battery-free wireless sensor dedicated to water diffusion monitoring in dielectric materials is presented. It is applied here to the monitoring of water diffusion in organic coatings. The method is based on the variation of the radiofrequency (RF) wave propagation in an open microstrip structure covered by the coating under consideration when water diffusion occurs. Simulations and experimental characterization of electromagnetic wave propagation in a microstip line and a planar stub resonator are described. The results achieved on the resonator prove unambiguously the feasibility of the method. As a consequence, the proposed sensor should be considered as a promising and reliable tool for civil engineering applications. [ABSTRACT FROM AUTHOR]

Hybrid coding techniques have been proposed recently to improve the coding capacity of chipless RF identification (RFID) tag. This paper examines the possibility to code information thanks to the magnitude level of the radar cross section (RCS) in addition to the more classical technique of frequency position (FP). Single-layer tags based on C-folded dipoles are designed to have different magnitude levels. A magnitude span of up to 15.2 dB is obtained for coupled resonators. A magnitude resolution of 3.5 dB is evaluated for practical applications based on the measurement of the realized tags in different configurations. The problem of tags applied to an unknown object is considered and a compensation technique is proposed for an object similar to a thin dielectric plate. [ABSTRACT FROM PUBLISHER]

In this paper a novel design of microstrip diplexer and triplexer using open loop resonators is presented. The proposed diplexer if formed by two band-pass filters for the Industrial Scientific Medical (ISM) applications at 5.8 GHz and the WIMAX applications (IEEE 802.16 WiMAX at 3.17 GHz to 4.2 GHz bands). The microstrip triplexer is designed for the Digital Communication System (DCS) at 1.8 GHz, WIMAX at 3.2 GHz and for the C-band at 4.4 GHz. Each device is formed by a set of filters with a matching network by using open loop resonators and a good arrangement of the transmission feed lines. Several parametric studies were achieved to study the influence of some critical parameters on the performances of the proposed circuits. The LC equivalent circuit of the band pass filter is examined and the values of its components are calculated. ADS Agilent and CST-MWS solvers are used to predict the electrical performances of the proposed circuits. The simulated frequency responses of these structures show good results with insertion losses around 2 dB, return losses better than 20 dB for all channels, and an isolation between all bands better than 20 dB. Besides, several transmission zeros are observed near the pass bands which enhance the selectivity and the isolation of the proposed devices. [ABSTRACT FROM AUTHOR]

This paper presents an innovative nonconventional exploitation of a self-resonant capacitive near-field link at UHF, for data communication, to be combined in a compact wireless power transfer (WPT) system. At UHF, an increased channel transfer efficiency is made possible by exploiting two faced auto-resonant structures, such as split-ring resonators (SRRs), one at each far-end side of the link. Their physical layouts are designed to ensure accurate prediction of both the resonant frequency and the resulting frequency-variable behavior of the two-port arrangement. This network is then used in a passive sensing system, based on a smart exploitation of the dc-power dc-load relationship of a standard RF identification (RFID) rectifier, to convert the data of a remote sensor, representing the system variable load. The reflected power variations at the transmitter side, due to the dc load variations, are successfully used to perform the sensor readout. The entire sensing system is first optimized by means of nonlinear circuit and electromagnetic (EM) simulations. Experimental data, compared to prior results, demonstrate the strength of the adopted approach. [ABSTRACT FROM PUBLISHER]

A planar 71-76 GHz integration platform is designed and fabricated for high-power radio-over-fiber (RoF) wireless photonic transmitters (PTs). The platform enables the integration of high-electron-mobility-transistor RF amplifiers and millimeter wave photodiodes (PDs), e.g., the waveguide triple transit region PD. An efficient electrical coupling between the PD chip and the rectangular waveguide (WR-12) output is attained through a low-loss grounded coplanar waveguide to a rectangular waveguide transition. The integration platform features a novel planar bias-tee design making use of a single quarter-wave coupled-lines (SCLs) section and slotted splitring resonators (SRRs). The bias-tee network enables proper biasing for the PD chip and protects the hybrid integrated RF amplifier from being damaged by the DC bias voltage. The introduced design together with the WR-12 output enables the development of high-power (>17 dBm) PTs for mobile backhaul links and radar applications. Experimental characterization of the designed platform is introduced and compared to numerical results. [ABSTRACT FROM AUTHOR]

In this paper, a compact diplexer based on coupled stepped impedance resonators (SIRs) is designed for Digital Communication System and the industrial, scientific and medical applications. The diplexer is composed from two band-pass filters operated at 1.8 and 2.45 GHz respectively. The size and the position of the SIR and the feed lines are determined through the theoretical design and the simulation. The diplexer has less than 2.2 dB insertion loss and more than 21 dB of isolation. The diplexer performances are investigated numerically by using Momentum ADS Agilent and CST microwave software. The electromagnetic simulated results of the proposed diplexer show a good agreement with the measured results. [ABSTRACT FROM AUTHOR]

A new three-dimensional (3-D) tunable bandpass frequency-selective structure (FSS) with wide tuning range is presented. The tunable FSS consists of a periodic array of printed circuit boards and a number of inserted metallic plates, where varactor-loaded \lambda /4 stepped-impedance resonators (SIRs) are constructed based on the propagation mode excited in the structure. By properly choosing the impedance ratio of the SIRs, a wide tuning range can be achieved. Detailed discussion is given to determine the key parameters involved in this tunable FSS, including varactor-loaded \lambda /4 resonators and coupling coefficient. Finally, a prototype tunable FSS is fabricated and measured. The results exhibit a 2:1 (65%) frequency tuning range from 1.4 to 2.75 GHz with an insertion loss of 4.5–1.0 dB within the passband. [ABSTRACT FROM PUBLISHER]

In this letter, we present super-resolution experiments from a single emission channel located in the far-field of an elastic metamaterial for Lamb waves. The experiment is performed in the kHz regime, with centimetric waves that are refocused numerically through cross-correlation computations. The originality of this approach lies in the direct link established between super-resolution results and the wavefield dispersion induced by a metamaterial made of long rods that are attached to a plate, and that behave as sub-wavelength resonators. We believe that such a clear origin of a far-field super-resolution experiment is of major interest for the design of a meta-lens for waves in plates. [ABSTRACT FROM AUTHOR]

ABSTRACT A compact wideband bandpass filter (BPF) with a broad stopband (4.1 f0) based on a triple-mode stub-loaded resonator (SLR) is presented in this article. Using even/odd mode analysis, the proposed SLR is found to have the ability to introduce three transmission poles in the passband. By appropriately adjusting the frequencies of these transmission poles and using a 0° tapped feed structure, the BPF can provide a wide passband and a sharp rejection over a broad stopband without using other lowpass or bandstop networks. The predicted results on S-parameters are compared with measured ones and good agreement is achieved. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:2878-2881, 2014 [ABSTRACT FROM AUTHOR]

A novel compact multiple-bit encoded chipless RFID tag using a stepped impedance resonator (SIR) is proposed. The main advantage of SIR compared with other resonators is the independent control over the fundamental as well as first harmonic frequency by varying either the impedance ratio (K) or length ratio (\alpha). The tag utilizes both the fundamental and the first harmonic frequency of the SIR to represent two bit information with a single resonator. The tag is capable of representing 2^2N number of bit combinations with N resonators. RFID tags are fabricated on C-MET LK4.3 (\varepsilonr =4.3 and \tan\delta =0.0018) and RT Duriod (\varepsilonr =2.2 and \tan\delta =0.0009) substrates. The structural information of the tag is encoded in the frequency spectrum, both in the magnitude and group delay of the backscattered signal. The data encoding capacity of the tag is enhanced by using the frequency shift coding technique. The proposed RFID tags have an operating range of 50 cm in the outdoor environment. Theoretical and numerical methods are used to verify the measured resonant frequencies of the tag. [ABSTRACT FROM PUBLISHER]

The generation in orotron with a two-row periodic structure (period, 0.5 mm; slit-to-period ratio, 0.25; heights of the lower and upper rows, 0.3 and 0.5 mm, respectively; and working voltages, 1500-18500 V) is experimentally studied using several configurations of open resonators. The working regimes employ (i) the second spatial harmonic, (ii) the first spatial harmonic, and (iii) surface waves (BWT regime). [ABSTRACT FROM AUTHOR]

ABSTRACT In this article, a triband bandpass filter for the applications of global system for mobile communications at 1.8 GHz, WiMAX at 3.5 GHz, and WLAN at 5.2 GHz with low insertion loss and high selectivity is presented. First, the triband passband responses are designed by tuning the length ratio (u) and impedance ratio (R) of asymmetric stepped impedance resonators (SIRs). Second, the band performances are improved by carefully arranging the coupling structure of the SIR. In this design, the split-end asymmetric SIRs are used to provide desired triband performances. Due to the four transmission zeros near the passband edge, the band selectivity of the proposed filter is much improved. The filter was fabricated and the measured results have a good agreement with the full-wave simulated results. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:1427-1430, 2014 [ABSTRACT FROM AUTHOR]