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High ScN fraction ScxAl1−xN has promise in important application areas including wide bandwidth RF resonators and filters, and ferroelectric devices such as non-volatile memory, but demands high crystal quality. In this work, the role of the nucleation layer (NL), ScxAl1−xN growth temperature, and strain management to preserve the wurtzite crystal structure are investigated to maximize both acoustoelectric and ferroelectric material properties for high ScN fraction ScxAl1−xN grown on SiC substrates. A 5 nm AlN nucleation layer reduces the x-ray diffraction 0002 reflection full width at half maximum (FWHM) for a Sc0.32Al0.68N film by almost a factor of 2, and reducing the growth temperature to 430 °C enables a Sc0.40Al0.60N film with a FWHM of 4100 arcsec (1.1°) while being only 150 nm thick. Grading the initial ScxAl1−xN layer from x = 0.32 to 0.40 suppresses the formation of rock-salt grain nucleation at the Sc0.40Al0.60N lower interface and reduces the anomalously oriented grain density by an order of magnitude. Increasing the total ScxAl1−xN growth thickness to 500 nm produces an average x = 0.39 ScxAl1−xN layer with a FWHM of 3190 arcsec (0.89°) and an anomalously oriented grain areal fill factor of 1.0%. These methods enable the lowest heteroepitaxial ScxAl1−xN FWHM reported for x ∼ 0.4, with layer thicknesses and defect densities appropriate for high frequency (>10 GHz) filter applications. [ABSTRACT FROM AUTHOR]

ABSTRACT A novel balanced switchable bandpass filter with all‐port reflectionless characteristics is proposed in this paper. The balanced switchable bandpass filter comprises a balanced switchable filtering section with bandpass response and two absorptive networks. The absorptive network proposed in this paper adopts only one structure to achieve both differential‐ and common‐mode reflectionless characteristics. The proposed switchable resonators in the filtering section and the proposed absorption networks excited under even‐ and odd‐modes are analyzed in detail. For the purpose of verification, a prototype is manufactured based on the simulated results, and it has a good consistency. The experimental results exhibit that the proposed balanced bandpass filter exhibits a differential‐mode bandpass filtering function and all‐port reflectionless performance in the ON‐state, differential‐mode isolation function, common‐mode suppression, and reflectionless behavior in the OFF‐state, which verifies the feasibility of the design theory. [ABSTRACT FROM AUTHOR]

Non‐volatile charge‐trap flash memory (CTM) co‐located with heterogeneous III‐V/Si photonics is demonstrated. The wafer‐bonded III‐V/Si CTM cell facilitates non‐volatile optical functionality for a variety of devices such as Mach–Zehnder Interferometers (MZIs), asymmetric MZI lattice filters, and ring resonator filters. The MZI CTM exhibits full write/erase operation (100 cycles with 500 states) with wavelength shifts of Δλnon‐volatile = 1.16 nm (Δneff,non‐volatile ≈ 2.5 × 10−4) and a dynamic power consumption <20 pW (limited by measurement). Multi‐bit write operation (2 bits) is also demonstrated and verified over a time duration of 24 h and most likely beyond. The cascaded second order ring resonator CTM filter exhibited an improved ER of ≈7.11 dB compared to the MZI and wavelength shifts of Δλnon‐volatile = 0.041 nm (Δneff, non‐volatile = 1.5 × 10−4) with similar pW‐level dynamic power consumption as the MZI CTM. The ability to co‐locate photonic computing elements and non‐volatile memory provides an attractive path toward eliminating the von‐Neumann bottleneck. [ABSTRACT FROM AUTHOR]

This article has designed a bandpass filter using a coplanar stripline stub (CPS) resonator consisting of open and short‐ended strip lines connected to the PIN diode switches. The use of spurline stub resonators inside CPS results in bandpass and bandstop filters, depending on the PIN diode switch configurations. The work presents a novel circuit architecture aimed at reducing the parasitic resonance of the spurline resonators and acquiring the necessary series stub characteristics. The proposed filter resonates at 6.9–9, 1.7–4.7, and 8.4 GHz when the PIN diodes are forward and reverse‐biased, respectively. It also resonates at 1–2.1, 4.8–5.3, and 6.9–9 GHz when one diode is reverse‐biased, and the other is connected in forward bias. An insertion loss below −0.55 dB and a return loss less than 10 dB have been obtained during simulation and measurement. The designed filter can find different applications for the 1.8 GHz GSM band, 2.4/5.8 GHz (WLAN), 3.6 GHz (WiMAX), long‐term evolution (LTE), and WIFI. The filter can be used in various multi‐frequency systems owing to its compact size. The measured and simulated findings of the proposed CPS spurline stub resonator wideband bandpass filters are substantially consistent. [ABSTRACT FROM AUTHOR]

A series of fourth‐order bandpass filters (BPFs) with compact footprints, broad bandwidth, high selectivity, linear phase and notched response are proposed. The sketch of these BPFs is in accordance with the combination of the eighth‐mode substrate integrated waveguide (EMSIW) and dual‐mode microstrip line (DMML) resonators. The DMML resonator is constructed by means of metallic via‐holes and pad in the double‐layered structures. Among them, the DMML resonator can provide two transmission poles. Besides, the cross coupling is introduced through the vertical slot or fan‐shaped aperture in the dual‐layered substrates. The coupling schemes of the proposed BPFs can introduce two transmission zeros in the vicinity of operating passband, and the coupled scheme also exhibits a relatively flat in‐band group delay. Notched frequency responses have been obtained by exploiting the U‐shaped resonator and folded‐ring resonator embedded with the mixed EMSIW and DMML BPFs. To validate the conceptual design, the proposed BPFs are simulated, fabricated and measured. Both the simulation and measurement have reached to a satisfactory agreement. [ABSTRACT FROM AUTHOR]

New coupling scheme substrate‐integrated waveguide (SIW) diplexers based on dual‐mode cavities are proposed for millimetre‐wave applications. Dual‐mode SIW cavities are simultaneously employed in common input and coupling cavity to produce filtering transmission poles and transmission zero (TZ). A common input SIW cavity with two orthogonal modes is employed instead of the traditional T‐junction for circuit miniaturisation, insertion‐loss reduction, and intrinsically high isolation. A critical dual‐mode SIW cavity with diagonally distributed modes has been employed in each channel to realise a controllable stopband TZ for high selectivity of passband's skirt. To further improve channel isolation and passbands' selectivity, a SIW diplexer based on dual‐ and single‐mode cavities is proposed, and four‐pole responses for each passband channel are designed. For the verification, two millimetre‐wave diplexers have been fabricated and tested. [ABSTRACT FROM AUTHOR]

In this paper, a novel inline network realization of non-resonating node (NRN) and dangling resonator (R) pair direct synthesis approach is presented. Arbitrary prescribed transmission zeros at real frequencies are realized through independently controlling the dangling resonators of the NRN-R pairs with impedance inverters between adjacent nodes. The bandpass element values for fourth order acoustic wave filter with a center frequency at 98 MHz are obtained through execution and mapping of the synthesis results based on the Generalized Chebyshev polynomials. The layout of prototype is presented. Finally, the prototype is constructed and measured using network analyzer to validate the proposed concept in realizing the BAW filter using Butterworth Lowpass Van Dyke (BVD) model. The filter has an insertion loss of 3.45 dB, a return loss of 8.5 dB, and two transmission zeros (TZs). In terms of implementation, this synthesis technique allows flexibility to synthesize and realize a conventional filter with transmission zeros as an inline network without cross couplings. This offers advantages in terms of size and cost reduction in filter production due to the inline resonator arrangement and reduced sensitivity in the design and tuning process. [ABSTRACT FROM AUTHOR]

In this article, a dual-band bandpass microstrip filter (DBBPF) is suggested and studied for RF/microwave applications. Our filter design method is based on two basic concepts; the use of metamaterial resonators in C-shaped split rings (C-SRR) to have the left-handed behavior (LH) with minimized losses and the feed by a microstrip line of significant length folded for the desired miniaturization. The two C-SRRs are optimized for a size of 6 × 3 mm² to cover the desired frequency bands and the two feed lines have a length of 37.1 mm to ensure the necessary adaptation. The search of a strong electromagnetic coupling between the two C-SRRs and the feed lines allowed us to choose the best position to place our resonators in the filter. The simulation of the filter parameters for two different proposed configurations shows two different qualities. According to the simulation outcomes for the two proposed filter configurations, two kinds of frequency response were obtained with different characteristics. For the first configuration where the two C-SRRs are separated by the folded arms of the two feed lines, the filter response is not clear. Contrary to that, the frequency response of the filter is desirable for the second configuration. The suggested filter which is represented by the second configuration has covered both bands (5.88 to 6.39 GHz and 10.75 to 11.16 GHz) for band-pass behavior. In addition, the analysis of the dispersion diagram allowed us to select the electromagnetic behavior associated with each band. [ABSTRACT FROM AUTHOR]

Abstract New coupling scheme substrate‐integrated waveguide (SIW) diplexers based on dual‐mode cavities are proposed for millimetre‐wave applications. Dual‐mode SIW cavities are simultaneously employed in common input and coupling cavity to produce filtering transmission poles and transmission zero (TZ). A common input SIW cavity with two orthogonal modes is employed instead of the traditional T‐junction for circuit miniaturisation, insertion‐loss reduction, and intrinsically high isolation. A critical dual‐mode SIW cavity with diagonally distributed modes has been employed in each channel to realise a controllable stopband TZ for high selectivity of passband's skirt. To further improve channel isolation and passbands' selectivity, a SIW diplexer based on dual‐ and single‐mode cavities is proposed, and four‐pole responses for each passband channel are designed. For the verification, two millimetre‐wave diplexers have been fabricated and tested.

The temperature properties of the incredible high performance (I.H.P.) structures on a multilayer lithium tantalate/silicon dioxide film/silicon substrate have been studied; these structures are used to improve the characteristics of devices on surface acoustic waves. Test structures have been simulated by the finite-element method in the COMSOL software and the temperature coefficient of frequency has been calculated. The calculated transfer coefficients of a resonator filter on a conventional single-crystal 36°YX-cut lithium tantalate substrate and an I.H.P. filter are compared at different temperatures. It is shown that the temperature coefficient of frequency can be minimized by fitting the thicknesses of the substrate layers. A comparison shows that the results obtained are in good agreement with the known data. The practical importance is that the simulation results and calculated parameters can be used for designing devices of different classes based on multilayer substrates (including those with I.H.P. structures). [ABSTRACT FROM AUTHOR]

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Copyright of Piezoelectrics & Acoustooptics is the property of Piezoelectric & Acoustooptic and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This work addresses the design of sub-terahertz narrow-band resonators for high performance and low-cost manufacturability. The intended application for these resonators is to realize narrow-band filters for passive millimeter-wave sounding of upper atmospheric humidity using the 380 GHz water vapor absorption line. Various narrow-band resonator designs and manufacturing processes were considered for this application. A design based on a waveguide split-ring resonator topology was selected to be developed and manufactured using laser machining. Experimental results are presented and compared with results from simulations for ten narrow-band resonators fabricated with a design center frequency in the WR-2.2 (325–500 GHz) waveguide band. [ABSTRACT FROM AUTHOR]

Compact and pole-controllable resonators and bandpass filter (BPF) using a composite right/left-handed transmission line (CRLH-TL) are designed in this study. The distributed constant line in the CRLH-TL has applied a tap-coupling technique, and one tap-coupled stub is loaded with the left-handed (LH) circuit. Attenuation poles are generated when the input susceptance of the stub diverges. In the tap-coupled CRLH-TL resonator, the attenuation pole is controlled at either the desired lower or higher region frequency than a resonant frequency by adjusting the circuit parameters. Also, the BPF constructed by the CRLH-TL resonators is designed based on a filter design theory, where the attenuation poles are located at lower and higher region frequencies than a negative-first-order frequency. The BPF with microstrip structure is fabricated using MEGTRON6 R-5775 ( ε r : 3.7, h: 0.63 mm, t: 18 μm), chip capacitors, and wire inductors. The simulated results show that the desired characteristics are approximately satisfied, i.e., we can design the CRLH-TL BPF which is controllable for the attenuation poles at both lower and higher region frequencies than a resonant frequency. The measured results are good agreement with the simulation. The negative-first-order frequency is generated at 2.00 GHz with 133 MHz bandwidth, i.e., the fractional bandwidth is 6.65 %. The resonator lengths in the BPF are shortened by 81.5 % and 75.0 % in comparison with a conventional half-wavelength ( λ / 2 ) openstub, and the size of the fabricated BPF is 0.18 λ g × 0.17 λ g . Therefore, a compact BPF with two controllable attenuation poles is realized by the tap-coupled CRLH-TL. [ABSTRACT FROM AUTHOR]

Purpose: This paper aims to present the simulation, fabrication and testing of a novel ultra-wide band (UWB) band-pass filters (BPFs) with better transmission and rejection characteristics on a low-loss Taconic substrate and analyze using the coupled theory of resonators for UWB range covering L, S, C and X bands for radars, global positioning system (GPS) and satellite communication applications. Design/methodology/approach: The filter is designed with a bent coupled transmission line on the top copper layer. Defected ground structures (DGSs) like complementary split ring resonators (CSRRs), V-shaped resonators, rectangular slots and quad circle slots (positioned inwards and outwards) are etched in the ground layer of the filter. The circular orientation of V-shaped resonators adds compactness when linearly placed. By arranging the quad circle slots outwards and inwards at the corner and core of the ground plane, respectively, two filters (Filters I and II) are designed, fabricated and measured. These two filters feature a quasi-elliptic response with transmission zeros (TZs) on either side of the bandpass response, making it highly selective and reflection poles (RPs), resulting in a low-loss filter response. The transmission line model and coupled line theory are implemented to analyze the proposed filters. Findings: Two filters by placing the quad circle slots outwards (Filter I) and inwards (Filter II) were designed, fabricated and tested. The fabricated model (Filter I) provides transmission with a maximum insertion loss of 2.65 dB from 1.5 GHz to 9.2 GHz. Four TZs and five RPs are observed in the frequency response. The lower and upper stopband band width (BW) of the measured Filter I are 1.2 GHz and 5.5 GHz of upper stopband BW with rejection level greater than 10 dB, respectively. Filter II (inward quad circle slots) operates from 1.4 GHz to 9.05 GHz with 1.65 dB maximum insertion loss inside the passband with four TZs and four RPs, which, in turn, enhances the filter characteristics in terms of selectivity, flatness and stopband. Moreover, 1 GHz BW of lower and upper stopbands are observed. Thus, the fabricated filters (Filters I and II) are therefore evaluated, and the outcomes show good agreement with the electromagnetic simulation response. Research limitations/implications: The limitation of this work is the back radiation caused by DGS, which can be eradicated by placing the filter in the cavity and retaining its performance. Practical implications: The proposed UWB BPFs with novel resonators find their role in the UWB range covering L, S, C and X bands for radars, GPS and satellite communication applications. Originality/value: To the best of the authors' knowledge, for the first time, the authors develop a compact UWB BPFs (Filters I and II) with BW greater than 7.5 GHz by combining reformed coupled lines and DGS resonators (CSRRs, V-shaped resonators [modified hairpin resonators], rectangular slots and quad circle slots [inwards and outwards]) for radars, GPS and satellite communication applications. [ABSTRACT FROM AUTHOR]

This paper elucidates the design of an S-band conformal loop filter. A combination of loop filter loaded with split ring resonator loading is proposed for the Band Pass Filter (BPF) in the proposed design. The reduced insertion loss and improved fractional bandwidth are achieved using the symmetrical tuning stubs in the loop filter. The operating range of the proposed filter in the S-band is between 2.12 GHz to 2.24 GHz, with a fractional bandwidth of 5.5% and a reduced insertion loss of 1.1 dB. The conformal geometry has been simulated on an EM solver, and the simulation results are analyzed. The simulation results of conformal geometry show an excellent match with the planar structure. The proposed filter is further fabricated, and the S-parameters are measured. The Sparameter results of the realized filter from simulations match closely with those from measurements of prototypes but with a small shift in frequency. The measured filter operates at 2.21 GHz to 2.41 GHz with a Fractional Band-Width (FBW) of 8.6% and a minimum insertion loss of 1.4 dB. [ABSTRACT FROM AUTHOR]

The article describes a novel low‐loss microwave diplexer based on compact planar filtering elements. These are composed of spiral resonators and etched directly onto the signal layer. Furthermore, their design and optimization prove to be easy, and their native high‐pass/low‐pass characteristics are perfectly suited for assembling a diplexer. To verify the claim, a diplexer is designed and fabricated. It operates at 1.9 GHz and 3.5 GHz, and it is intended for personal communications service and 5G applications. The proposed device has an active area of 15.5 mm × $\times $ 19.5 mm. It shows an insertion loss of 0.35 dB and 0.28 dB for the two channels, representing the lowest data reported in the literature for this kind of device and technology. Additionally, the −10 dB‐fractional bandwidths for the lower and upper bandwidths are 40.6% and 20.2%, respectively, and isolation is at least 25 dB for both channels. [ABSTRACT FROM AUTHOR]

This letter presents the design of a microstrip-based diplexer for the applications of the Internet of Things (IoT). By incorporating stub-loaded coupled line resonators, the diplexer achieves significant enhancements in its passband performance. Specifically engineered to operate at precise frequencies of 2.55 and 3.94 GHz, the diplexer demonstrates improved isolation and selectivity through the integration of five transmission poles (TPs). A comprehensive analysis is conducted, evaluating crucial parameters, such as size, insertion loss, return loss, and isolation. The diplexer is fabricated on a compact Rogers Duroid 5880 substrate, and experimental measurements validate its effectiveness, exhibiting a low insertion loss of 0.3 dB at 2.55 GHz and 0.4 dB at 3.94 GHz, in close agreement with simulated predictions. The proposed design, featuring stub-loaded coupled line resonators, showcases highly promising passband characteristics, making it a compelling solution for efficient multiplexing of diverse frequency bands in wireless communication applications within the IoT and network-on-chip (NoC) domains. [ABSTRACT FROM AUTHOR]

This letter introduces a straightforward method for designing a tri-band bandpass filter using a loaded symmetrical dual-step impedance resonator (D-SIR) structure, augmented by multiple open and short circuit stubs. The resulting filter operates at 2.2, 7.9, and 14.1 GHz, showcasing high-band selectivity. Experimental measurements confirm six transmission zeros and six transmission poles across the passbands, yielding fractional bandwidth (FBW) of 42.6%, 63.8%, and 27.9%. Particularly noteworthy is the broader upper stopband rejection, enhancing the filter’s overall performance. The design achieves impressive performance metrics, with minimal insertion loss (IL) of 0.71, 0.87, and 0.76 dB, accompanied by substantial return loss (RL) of 23, 18, and 13.8 dB across the three passbands. Furthermore, the fabricated design have a compact size of ($0.20\times 0.15$) $\lambda _{g}$ on a Rogers Duroid RT/5880 substrate. Remarkable agreement between measured and simulated results underscores its viability for Internet of Things-based communication systems. [ABSTRACT FROM AUTHOR]

As a core functional material in acoustic resonators and filters, the elasticity of aluminum nitride (AlN) piezoelectric thin film and its correlated intrinsic properties deserve priority attention. This paper presents an in‐depth investigation of elastic softening and stiffening effect induced by stress loading in AlN piezoelectric thin film. Based on the Born‐Lande equation, the physical mechanism of such new intrinsic elastic property is revealed and predicted quantitatively for the first time from the perspective of atomic interaction forces. It is found that a maximum 6.7% modulation range of elasticity coefficient can be achieved under ultimate stress loading conditions from (−2.5, −2.5) to (2.5, 2.5) GPa. © 2023 Institute of Electrical Engineer of Japan and Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

With the development of wireless communication, increasing signal processing presents higher requirements for radio frequency (RF) systems. Piezoelectric acoustic filters, as important elements of an RF front-end, have been widely used in 5G-generation systems. In this work, we propose a Sc0.2Al0.8N-based film bulk acoustic wave resonator (FBAR) for use in the design of radio frequency filters for the 5G mid-band spectrum with a passband from 3.4 to 3.6 GHz. With the excellent piezoelectric properties of Sc0.2Al0.8N, FBAR shows a large K e f f 2 of 13.1%, which can meet the requirement of passband width. Based on the resonant characteristics of Sc0.2Al0.8N FBAR devices, we demonstrate and fabricate different ladder-type FBAR filters with second, third and fourth orders. The test results show that the out-of-band rejection improves and the insertion loss decreases slightly as the filter order increases, although the frequency of the passband is lower than the predicted ones due to fabrication deviation. The passband from 3.27 to 3.47 GHz is achieved with a 200 MHz bandwidth and insertion loss lower than 2 dB. This work provides a potential approach using ScAlN-based FBAR technology to meet the band-pass filter requirements of 5G mid-band frequencies. [ABSTRACT FROM AUTHOR]

The remarkable light perception abilities of the mantis shrimp, which span a broad spectrum ranging from 300 nm to 720 nm and include the detection of polarized light, serve as the inspiration for our exploration. Drawing insights from the mantis shrimp's unique visual system, we propose the design of a multifunctional imaging sensor capable of concurrently detecting spectrum and polarization across a wide waveband. This sensor is able to show spectral imaging capability through the utilization of a 16-channel multi-waveband Fabry–Pérot (FP) resonator filter array. The design incorporates a composite thin film structure comprising metal and dielectric layers as the reflector of the resonant cavity. The resulting metal–dielectric composite film FP resonator extends the operating bandwidth to cover both visible and infrared regions, specifically spanning a broader range from 450 nm to 900 nm. Furthermore, within this operational bandwidth, the metal–dielectric composite film FP resonator demonstrates an average peak transmittance exceeding 60%, representing a notable improvement over the metallic resonator. Additionally, aluminum-based metallic grating arrays are incorporated beneath the FP filter array to capture polarization information. This innovative approach enables the simultaneous acquisition of spectrum and polarization information using a single sensor device. The outcomes of this research hold promise for advancing the development of high-performance, multifunctional optical sensors, thereby unlocking new possibilities in the field of optical information acquisition. [ABSTRACT FROM AUTHOR]

The performance requirements for filters in the microwave frequency band are particularly stringent, particularly in terms of high bandwidth and out-of-band rejection. However, meeting these requirements within the constraints of a compact size presents a significant challenge. A coupled step-impedance resonator bandpass filter is proposed. The filter combines U-shaped branches and Lshaped branches to create multiple resonance points while expanding the bandwidth, and the in-band ripple is also improved by this folded structure that greatly reduces the filter size. The microstrip filter measures only 9.6 mm x 8.8 mm x 1.1 mm, has a center frequency of 4.65 GHz, and achieves a relative bandwidth of 60.2%. The filter can be used in 5G n77 (3300 ~ 4200 MHz), n78 (3300 ~ 3800 MHz), n79 (4800 ~ 4960 MHz), and WLAN (5150 ~ 5850 MHz) bands. In addition, the filter has a left-side rectangular coefficient of 1.12, insertion loss < 0.4 dB, and return loss better than 17 dB. [ABSTRACT FROM AUTHOR]

A novel enlarging fractional bandwidth (FBW) technique for acoustic‐wave‐lumped‐element resonator (AWLR)‐based bandpass filters is presented. The new technique is based on a series of matching inductors that replace the parallel or series acoustic wave (AW) resonators of AW filters to beak the bandwidth constraint of the ladder‐type structure. In addition, the transmission response analysis of the proposed AWLR‐based filter is provided. A prototype of the AWLR‐based filter is fabricated and tested to validate the proposed FBW widening technique. The measured insertion loss, FBW, and out‐of‐band rejection are 1.5 dB, 1.63kt2 (kt2 is the electromechanical coupling coefficient of the AWR), and 38 dB, respectively. [ABSTRACT FROM AUTHOR]

We propose the design of three port photonic and plasmonic demultiplexers where filtering toward the two outputs is based on the phenomena of Fano resonances and electromagnetically induced transparency (EIT). We use a Cross-shape resonator in one output and a U-shape resonator composed of two stubs in the other output. We give a theoretical demonstration of the geometrical parameters of both resonators in order to filter one wavelength in one output while leaving the other output unperturbed. These results are confirmed by experimental validation in the radio frequency domain and a numerical simulation in the infrared (IR) domain using plasmonic metal–insulator–metal waveguides. The Cross resonator in the first output can give rise to an EIT resonance, whereas the U-shaped resonator in the second output may exhibit both EIT and Fano resonances depending on the lengths chosen for the stubs. Therefore, different demultiplexing schemes can be proposed such as achieving a Fano resonance in one output and an EIT in the other, or EIT resonances in both outputs. The Fano resonance is obtained by bringing resonance close to transmission zero, whereas the EIT results from the squeezing of resonance between two transmission zeros. When the widths of the resonances tend to zero, they transform to trapped or bound states in the continuum with an infinite lifetime. We show that the crosstalk between the two channels can be reduced to − 82 dB and the sensitivity can reach 2390.8 nm/RIU, RIU is the refractive index units. Finally, we highlight the performance of our design as a high sensitive filter and sensor in the IR domain. In this work, the analytical calculations and demonstrations are performed by using Green's function approach, the experimental verifications are realized by means of coaxial cables operating in the radio frequency range and the numerical simulations are obtained using the finite element method via Comsol Multiphysics software. [ABSTRACT FROM AUTHOR]

In this paper, a wideband circularly polarized (CP) filtering dielectric resonator antenna (FDRA) is proposed. The proposed antenna consists of a microstrip-Y-shaped slot line coupled feeding structure and a grooved DRA. The Y-shaped slot line not only serves as an energy coupling structure to excite the orthogonal modes (TEx 111 mode and TEy 111 mode) of DRA, forming the CP radiation effect, but also generates two resonant modes, thereby broadening the antenna impedance bandwidth. In addition, due to the groove engraved on the diagonal of the DRA top wall, the antenna CP performance within the passband is enhanced. Finally, by loading a shorting stub and a spur line on the microstrip feedline, radiation nulls are generated on both sides of the antenna passband, resulting in a quasi-elliptical filter response in the antenna gain curve. To further verify the performance of the antenna design, a prototype CP FDRA is fabricated and measured. The measurement results indicate that the antenna achieves a -10 dB impedance bandwidth of 46.1% (2.67-4.27 GHz) and an axial ratio (AR) bandwidth of 23% (3.08-3.88 GHz), with an average measured gain of approximately 4.9 dBi. This antenna exhibits high-frequency selectivity and an out-of-band suppression level exceeding 10 dB. [ABSTRACT FROM AUTHOR]

Poly(vinylidene fluoride-trifluorethylene) (P(VDF-TrFE)) has promising potential applications in radio-frequency filters due to their excellent piezoelectric properties, flexibility, and stability. In this paper, a flexible film bulk acoustic wave filter is investigated based on P(VDF-TrFE) as piezoelectric film. A new method based on three-step annealing is developed to efficiently remove the porosity inside the P(VDF-TrFE) films so as to improve its properties. The obtained film achieved high β-phase content beyond 80% and a high piezoelectric coefficient of 27.75 pm/V. Based on the low porosity β-phase films, a flexible wide-band RF filter is designed, which consists of a bulk acoustic wave resonator and lumped inductor-capacitor elements as a hybrid configuration. The resonator sets the filter's center frequency, while the lumped LC-based matching network extends the bandwidth and enhances out-of-band rejection. The testing results of the proposed wide-band filter show its good performance, with 12.5% fractional bandwidth and an insertion loss of 3.1 dB. To verify the possibility of folding and stacking the flexible bulk acoustic wave devices for high-density multi-filter integration in MIMO communication, bending tests of the filter are also conducted with the bending strain range up to 5500 με. The testing results show no noticeable performance degradation after four bending cycles. This work demonstrates the potential of β-phase P(VDF-TrFE) bulk acoustic wave filters to expand the scope of future flexible radio-frequency filter applications. [ABSTRACT FROM AUTHOR]

This article presents a four-port Multi-Input Multi-Output (MIMO) antenna based on Dielectric Resonators (DR), showcasing excellent filtering characteristics, high isolation between ports, and strong diversity performance. The initial step introduces a single-port filtering Dielectric Resonator Antenna (DRA) utilizing the HEM11δ mode, featuring a complementary split ring resonator (SRR) feed structure that excites the cylindrical DR. This feed structure enables the independent adjustment of one resonance frequency and two radiation nulls. The experimental results confirm that the designed radiator works in between 2.35 and 2.57 GHz with an isolation level of more than 25 dB. The value of the gain is around 5.0 dBi within the operating band, while it is less than −15 dBi outside the working band. All these features make the designed MIMO radiator applicable for IoT applications. [ABSTRACT FROM AUTHOR]

A dual-band dual-sense (DBDS) circularly polarized (CP) filtering dielectric resonator antenna (FDRA) with a quasi-elliptic band-pass response is proposed in this paper. The proposed antenna consists of a rectangular dielectric resonator (DR) with a Z-shaped strip at the top, a ground plane with a rectangular slot, and a microstrip feedline etched with a section of the spur line. By using the microstrip coupled slot line structure to excite DR with a Z-shaped strip, different senses of circular polarization are achieved in the two bands. The results show that the lower and upper bands are independently controlled by the strip and the DR, respectively. In addition, three radiation nulls are generated at the passband's edge by elaborately designing a half-wavelength open stub and etching the spur line. For demonstration, a prototype DBDS CPFDRA is fabricated and measured. The measurements illustrate that the antenna achieves a wide impedance bandwidth of 38.2%, as well as a dual axial ratio (AR) bandwidth of 2.2% for the left-hand circular polarization (LHCP) and 4% for the right-hand circular polarization (RHCP). The realized gain exhibits a decline of 25 dB at the passband edge, indicating high selectivity. [ABSTRACT FROM AUTHOR]

The monolithic design of a compact bandpass filter X-band is made on the technology of multilayered printed circuit boards. Quarter-wave stripline resonators of the filter have two conductors divided by a layer of prepreg having low parameters that bond together the design. This eliminates the influence of the prepreg on the characteristics of the devices, ensuring good repeatability of filters in mass production. To increase the high-frequency stopband of the filter, one of the conductors of each resonator is cut in half by a transverse slit. The constructive sizes of the device were obtained by parametric synthesis using the electrodynamic analysis of its 3D model. The experimental data of the five-order filter are in good agreement with the electromagnetic simulation of filter of the 3D model. The experimental device has a central frequency of the passband of 10 GHz and a fractional bandwidth of 5.7%, and its dimensions and weight are 18.0 × 5.4 × 2.1 mm3 and 0.5 g. The important advantage of the developed design is the possibility of its installation on the board using the surface mounting method. [ABSTRACT FROM AUTHOR]

Adaptive deep brain stimulation (aDBS) is a promising concept in the field of DBS that consists of delivering electrical stimulation in response to specific events. Dynamic adaptivity arises when stimulation targets dynamically changing states, which often calls for a reliable and fast causal estimation of the phase and amplitude of the signals. Here, we present an open-hardware implementation that exploits the concepts of resonators and Hilbert filters embedded in an open-hardware platform. To emulate real-world scenarios, we built a hardware setup that included a system to replay and process different types of physiological signals and test the accuracy of the instantaneous phase and amplitude estimates. The results show that the system can provide a precise and reliable estimation of the phase even in the challenging scenario of dealing with high-frequency oscillations (~250 Hz) in real-time. The framework might be adopted in neuromodulation studies to quickly test biomarkers in clinical and preclinical settings, supporting the advancement of aDBS. [ABSTRACT FROM AUTHOR]

Ceramic waveguide components play a critical role in modern microwave semiconductor systems. For the first time, this work reports experimental results obtained when dielectric ceramics are abrasive-machined into waveguide components. This process will cause subsurface damage (SSD), resulting in a deviation in their working frequency which can degrade the performance of the system. For a substrate-integrated waveguide (SIW) resonator working at 10.1 GHz, SSD with a depth of 89 um can cause a maximum frequency offset of 20.2%. For a mm wave component working at 70 GHz, the corresponding frequency offset could increase to 169%. Three resonator SIW filters with SSD are studied, and the results demonstrate that the frequency offset induced by SSD can reduce the pass rate of the filters from 95.4% to 0%. A theoretical analysis is performed to reveal the mechanism and to offer a quantitative estimation of the limiting range of the offset caused by SSD. Feasible methods for reducing the offset caused by SSD, such as structure design, processing optimization, and material reinforcement, are discussed. [ABSTRACT FROM AUTHOR]

In this letter, a compact circularly polarized (CP) microstrip patch filtenna designed by reusing dual‐mode substrate integrated waveguide (SIW) cavity is proposed. The dual‐mode SIW cavity, operating at its TE120 and TE210 modes, can be used not only as the first stage resonator of the filtering network but also feeds the four microstrip patches working at their TM10 and TM01 modes. A pair of asymmetric perturbed posts is inserted in the SIW cavity to perturb the electric field distributions of TE120 and TE210 modes so as to achieve one axial ratio (AR) minima. The other AR minima is realized by sequentially exciting the four orthogonal microstrip patches via the four rectangular slots that are etched on the top surface of the SIW cavity. In addition, four metal posts penetrated the SIW cavity is employed to improve the impedance matching. For verification, a CP filtenna prototype centered at 5.13 GHz is designed, manufactured, and tested. The measured results agree well with the simulated ones, demonstrating a fractional impedance bandwidth of 6.9% (4.95–5.3 GHz), a 3 dB AR bandwidth of 4.2% (5–5.21 GHz), and a maximum boresight realized gain of 8.4 dBic. [ABSTRACT FROM AUTHOR]

This article proposes the development of a novel structure based on the cascading of two asymmetrical micro-optical ring resonators (AMORRs) and evaluates its performance as an optical filter. Two AMORR structures, having a single input with three output buses (1 × 3) and a dual input with double output buses (2 × 2), have been designed with four asymmetrical rings and cascaded in such a way as to configure the (2 × 6) buses. The proposed structures are modelled in the Z-domain using the delay line approach. Frequency response studies of the proposed structures are performed in MATLAB. FSR (free spectral range) and crosstalk are successfully computed from the frequency response of the proposed AMORRs. The proposed AMORRs are then designed in OptiFDTD using the parameters of the Z-domain transfer function. The frequency response of designed AMORRs is computed in OptiFDTD software and compared with that obtained in MATLAB. The FSR computed from both characteristics is very close. The field distribution of the designed AMORR has been presented in the article. The optimum coupling coefficients obtained in MATLAB are used to design directional optical couplers. OptiSystem software (version 20.0) is used to develop the optical model and assess the system's performance in optical communication. A high Q-factor (> 29) is obtained at each bus with a lower BER (Bit Error Rate) value, giving a wide-open eye diagram. These analyses show that the proposed structures have a large FSR with negligible crosstalk and a high Q-factor with wide-open eye diagrams, providing noise-free systems to accommodate several communication channels. [ABSTRACT FROM AUTHOR]

A novel microstrip loop-type resonator with four resonant modes is proposed in this letter. The resonator is formed by a loop-type microstrip line loaded with four shorted stubs. It has a symmetrical structure, thus the odd-even-mode method is adopted to implement the resonant analysis. The novelty of the proposed resonator lies in two aspects. One is that its resonant frequencies can be adjusted in a more flexible way. The other is that its resonant modes have a uniform electromagnetic field distribution, which is beneficial for the excitation of resonant modes. For the purpose of demonstration, based on the novel resonator, a single-band bandpass filter with four transmission poles and a dual-band bandpass filter with two transmission poles in each passband are constructed. Additionally, sourceload cross coupling is introduced, and several transmission zeros are generated in the stopband, which improves the out-of-band performance greatly. The designed single-band filter has the central frequency of 2.4 GHz and fractional bandwidth (FBW) of 4.5%, and the dual-band filter has the central frequency of 1.8/2.4 GHz and fractional bandwidth of 2.0%/2.5%. The two bandpass filters are designed, fabricated, and measured. Agreement between the simulated and measured results verifies the effectiveness of the proposed resonator and filters. [ABSTRACT FROM AUTHOR]

We demonstrate a fourth-order Vernier serious-coupled microring resonator (MRR) filter based on the InGaAs/InAlAs five-layer asymmetric coupled quantum-well (FACQW) waveguide. As the tuning of the main resonance wavelength is driven by the electrorefractive index change in the FACQW layer caused by the quantum-confined Stark effect (QCSE), the MRR filter has lower tuning power consumption and high-speed operation. The free spectral range (FSR) of the MRR filter is extended to 9.4 nm. The main resonant peak is discretely tuned within one FSR, leading to an increase in the wavelength channel. [ABSTRACT FROM AUTHOR]

Reconfigurable photonic filters show great promise as a potential solution to meet the evolving needs of future microwave communication systems. By integrating high-performance filters into programmable microwave photonic processors, they can provide significant benefits for signal processing applications. The development of an algorithm that can automatically characterize and reconfigure the filter using a single optical input and output port is essential for this purpose. This paper presents an optimization technique for a fully tunable ring-assisted Mach–Zehnder interferometer filter. The proposed filter design eliminates the need for monitoring components and employs a novel algorithm that operates independently in each ring by switching between the two arms of the filter. In addition, the filter can be configured to implement different filter architectures, allowing for flexible filtering requirements. Measurements were performed using the device as an interleaver, implementing different types of infinite impulse response filters in the optical and radio frequency domains. Side-coupled integrated spaced sequence of resonator filters were also implemented by reconfiguring the same device. These results demonstrate the exceptional reconfigurability of the filter design proposed herein in terms of bandwidth and central frequency. [ABSTRACT FROM AUTHOR]

Triangular resonators re-shaped with Sierpinski geometry were designed, manufactured, and tested for potential applications in the K-Band. Prototypes of band-stop filters working around 20 GHz and 26 GHz, interesting for RADAR and satellite communications, were studied in a coplanar waveguide (CPW) configuration. Single and coupled structures were analyzed to give evidence for: (i) the tuning of the resonance frequency by increasing the internal complexity of the triangle and (ii) resonance enhancement when coupled structures are considered. The exploited devices were part of the more extended family of metamaterial-inspired structures, and they were studied for their heuristic approach to the prediction of the spectrum using experimental results supported by electromagnetic simulations. As a result, a Sierpinski resonator, not only fed into but also fully embedded into a CPW environment, had a frequency response that was not easily determined by classical theoretical approaches. [ABSTRACT FROM AUTHOR]

This paper studied the impact of the microstructure of interdigital electrodes on the performance of surface acoustic wave (SAW) resonators and proposed an innovative piston, dummy finger and tilt (PDT) structure, which was then applied to the GLONASS L3 band filters. Through the adoption of 3D finite element simulation (FEM), photolithography, and testing on an incredible high-performance surface acoustic wave (I.H.P. SAW) substrate, it is concluded that the total aperture length is 20T (T is period), resulting in a more optimal resonator performance; changing the width and length of the piston can suppress transverse modes spurious, but it does not enhance impedance ratio; to further improve the quality of the SAW resonator, the proposed PDT structure has been experimentally proven to not only effectively suppress transverse modes spurious but also possess a high impedance ratio. By utilizing a PDT structure within a "T + π" topology circuit, we successfully designed and manufactured a GLONASS L3 band filter with a bandwidth of 8 MHz and an insertion loss of 3.73 dB. The design of these resonators and filters can be applied to the construction of SAW filters in similar frequency bands such as BeiDou B2 band or GPS L2/L5 band. [ABSTRACT FROM AUTHOR]

This work presents the development of a bandstop filter with a tunable response. Varactor diodes are used as control elements. Studies and investigations demonstrate the influence of the variable capacitance on the input admittance and on the S-parameters frequency responses of the proposed square-ring resonator geometry. The design of the square-ring resonator is based on mathematical modeling of ideal transmission lines, considering parameters of characteristic admittance and electrical length for odd and even excitation modes. Based on S-parameters in ports, an equivalent circuit model of the resonator geometry is presented. The corresponding results are compared with numerical simulations. Comparative analyses are presented in order to guide the process of optimizing the physical dimensions of the layout. A prototype with dimension 0.0272 λg2 was designed, fabricated, and tested. As a measured result, a filter with two rejection bands was obtained, the first at 0.6–1.15 GHz and the second at 1.71–2.28 GHz, with 63.0 and 29.0% tuning range, respectively. In comparison with bandstop filters from the literature, the proposed reconfigurable filter presents a larger tuning range for the first band, sufficient inband rejection levels for several applications, and reduced physical dimensions. The proposed configuration is an attractive reconfigurable filtering device for use in modern communication systems operating below 3.0 GHz. [ABSTRACT FROM AUTHOR]

A low-profile dielectric resonator (DR) filter is proposed to achieve the feature of high integration and wide stopband. The high integration is due to the structure of printed circuit board (PCB) substrate instead of metal cavity, which can be easily integrated with other planar circuits. Thus, the proposed design can improve the integration level and reduce installation errors. Moreover, the out-of-band harmonics can be well suppressed by the structure combined with introducing rectangular hollowing in the center of the dielectric block, coupling the feed and loading 1/4λ wavelength branch. For demonstration, it is fabricated and measured. The simulated and experimental results with good agreement are presented, the insertion loss is as low as 1.1 dB, the profile height is only 0.77λg, and the stopband reaches 2.61f0. [ABSTRACT FROM AUTHOR]

Bulk acoustic wave (BAW) filters have been extensively used in consumer products for mobile communication systems due to their high performance and a standard CMOS compatible integration process. However, a traditional BAW filter generally presents only one frequency transmission band; hence, it cannot meet the demands of multi-mode wireless communication systems. In this work, we propose a radio frequency dual-band filter based on a dual-mode film bulk acoustic resonator (FBAR). The dual-mode FBAR consists of molybdenum electrodes and an aluminum nitride film with a c axis tilt angle, which leads to the coexistence of the longitudinal mode and the shear mode in the resonator. The influence of the tilt angle on the resonant frequency and electromechanical coupling coefficient of the dual-mode FBAR is investigated. Subsequently, the behaviors of the dual-mode FBAR have been emulated by a modified Butterworth–Van Dyke model with two motional branches, which is further used to design and optimize the dual-band filter. The dual-mode FBAR-based filters connected in a ladder configuration present two dual passbands of 43 MHz and 105 MHz, respectively. The developed filters with dual passbands can give an inspiration to the design of BAW devices in modern wireless communications. [ABSTRACT FROM AUTHOR]

AlScN films are produced in a commercial metal–organic chemical vapor deposition (MOCVD) system modified to low‐vapor‐pressure Sc metal–organic precursors. Growth conditions are optimized for surface morphology, film stress, and piezoelectric coefficient across a range of compositions. Epitaxial structures are designed to eliminate internal tensile stresses that develop during the film growth as well as prevent surface adatom interactions unique to the MOCVD process. From these films, wide‐bandwidth resonators and filters are manufactured using a novel microelectromechanical‐based bulk acoustic wave (BAW) transfer process. When tested on‐wafer, resonators exhibit a keff2$k_{\text{eff}}^{2}$ of 10.5%, and a Qmax$Q_{\text{max}}$ value of 1400. Ladder‐type RF filters using these resonators are fabricated at 6.2 GHz and show improved performance over filters fabricated using physical vapor deposition‐deposited AlScN. [ABSTRACT FROM AUTHOR]

N-order bandpass filter (BPF) with parallel resonators and cross and mixed couplings can have (N + 1) transmission zeros (TZ) located on the complex plane s = σ + jω. TZs at real frequencies (jω axis) are also called attenuation poles (AP). The authors propose an alternative possibility of AP forming in filters using resonators with special properties, which significantly increases the AP number from (N + 1) to (3N + 1). Increasing the AP number with fewer resonators allows us to increase the selectivity and rejection level and reduce BPF insertion losses. The special properties of resonators are that their input admittance Y has one or two poles (ωp1, ωp2) located next to the resonance frequency ω0. This leads to the appearance of AP in a BPF. We propose and analyze three resonators with special properties. They are formed by a cascade connection of a quarter-wave resonator and lumped L and C. The input of the resonators is located on the side of the lumped elements. It was found that the Q-factors of lumped elements do not affect the filter losses in the passband. The reduction of QL and QC leads only to the decrease of the AP "depth." For the first time, 7 APs were implemented in the experimental second-order microstrip BPF. [ABSTRACT FROM AUTHOR]

In this article, a novel nanoplasmonic wavelength filter using new T-shaped resonators is designed. In the proposed design, T-shaped resonators are placed diagonally in the waveguide. This dual band-pass filter, wavelengths 1080 nm and 1320 nm, has a metal-insulation-metal structure, and the Drude, Drude-Lorentz, and Drude-Critical Points models have also been used in the numerical simulations. Moreover, the intensity of transmission power and the amount of resonance can be adjusted and changed in accordance with the base length of the resonators. The proposed filter can limit light to dimensions below the wavelength (in the nanometer range), making it suitable for optoelectronic integrated circuits. Furthermore, by tuning the parameters of the structure, it will be possible to achieve 93% and 73% of the transmission power intensity. Also, the artificial neural network model is presented to predict the transmission rate of the filter and optimize the dimensions of the resonators for better performance. [ABSTRACT FROM AUTHOR]

Novel high-entropy Sr(La 0.2 Nd 0.2 Sm 0.2 Eu 0.2 Gd 0.2)AlO 4 ceramics with a layered perovskite structure have been prepared via the standard solid-state reaction method. The design of high-entropy improves the bond valence and subsequently optimizes the large negative temperature coefficient of resonant frequency (τ f = −32 ppm/°C) of the simple SrLaAlO 4 ceramics. Excellent temperature stability (τ f = −6 ppm/°C) together with a relative permittivity (ε r) of 18.6 and a quality factor (Qf = 14,509 GHz) are obtained in Sr(La 0.2 Nd 0.2 Sm 0.2 Eu 0.2 Gd 0.2)AlO 4 ceramics sintered at 1475 °C. It indicates that the present ceramics have great application prospects in passive microwave components such as resonators and filters. Meanwhile, significant improvements in compressive strength and strain are achieved, which are 1040 MPa and 15.7% for Sr(La 0.2 Nd 0.2 Sm 0.2 Eu 0.2 Gd 0.2)AlO 4 compared to 583 MPa and 12% in SrLaAlO 4. The enhanced mechanical properties originate from the dislocation strengthening mechanism as the intertwining of interlayer lattices is revealed from the high-resolution transmission electronic micrographs. [ABSTRACT FROM AUTHOR]

Existing communication systems require efficient, compact and portable microstrip filters so that it contributes in enhancing the performance of communication system. Existing communication at Sband system requires spurious free signal transmission as well as reduced insertion and return loss, improved bandwidth and sharp roll off rate. The stated parameters could be improved through the design of a compact resonator filter. Hence, in this paper the design, development and characterization of a dual mode close loop resonator filter on microstrip structure at S-band is discussed. The proposed resonator filter design exhibits performance improvement in terms of insertion loss (<1 dB), return loss (Better than 12 dB), Bandwidth (>5%), sharp role off as compared to existing filter. Dual mode operation of close loop resonator filter is explained through the time varying field distribution. The size optimization of the designed resonator filter is accomplished without altering electrical parameter. The designed resonator filter has also been fabricated on two different substrates and comparative analysis has been carried out. Finally the realized filters have been characterised for its suitability in space applications. [ABSTRACT FROM AUTHOR]

This paper presents a new simplified procedure to design a fourth-order coupled resonator filter. This procedure does not require the calculation of complicated eigenvalues to develop the required coupling matrix. It starts with studying the effects of different coupling mechanisms on the performance of the overall filter structure. Then, these coupling mechanisms are combined to obtain the design of the required filter. This procedure may be more suitable for machine learning procedure to design coupled-resonator filters. The proposed method is used to design a substrate integrated waveguide (SIW) bandpass filter for sub-six GHz 5G applications. The designed SIW bandpass filter operates in the frequency range from 3.7 GHz to 3.98 GHz which covers the new C-band 5G network with a fractional bandwidth (FBW) of 28% and is centered at 3.84 GHz. This filter is fabricated and measured for verification. [ABSTRACT FROM AUTHOR]