Dual-band Resonator Research Articles

Dual-band D-shaped SPR fiber sensor based on birefringence analysis

We propose and numerically investigate a dual-band D-shaped surface plasmonic resonance (SPR) fiber sensor, which consists of a simple D-shaped fiber with metallic nanowire grating on the polished flat surface. The correlation between resonance coupling and degenerate mode properties are fully investigated based on birefringence analysis. To the best of our knowledge, it is the first report that plasmon resonances occurs in both directions which are parallel and perpendicular to the polished surface in this simple structure. The sensing figure of merit (FOM) of the two orthogonally SPR modes reach up to 200 and 190 RIU−1. The proposed structure would be a good candidate for dual-channel biosensing, medical diagnosis and environmental monitoring in a wide refractive index range of 1.31–1.37.

Altering the Multimodal Resonance in Ultrathin Silicon Ring for Tunable THz Biosensing.

A technique is implemented for altering the multimodal resonance generated in an ultrathin silicon ring resonator-based terahertz (THz) absorber. The absorber provides the dual-band resonance with the excitation of magnetic and electric dipole in the lower and upper band, respectively. The field of magnetic and electric dipoles is altered using a non-resonant graphene ring placed in the center of the generated dipolar arrangement and the tunability and perfect absorption is achieved. A circuit model is prepared using transmission line method and absorber operation is verified. The proposed absorber can be utilized as a biosensor for the detection of malaria virus and glucose percentage in water. The sensor offers highest sensitivity as 0.29 and 0.27 THz per thickness unit change and quality factor as 117.53 and 245 in the lower and upper band, respectively during the sensing of analyte thickness. Also, it offers the sensitivity as 0.20 and 0.10 THz per refractive index unit change and quality factor as 105.28 and 211.84 in the lower and upper band, respectively during refractive index sensing. Moreover, the structure remains insensitive to polarization angle of the incident electromagnetic wave.

Design of electrostatically tunable terahertz metamaterial with polarization-dependent sensing characteristic

We present a design of MEMS-based tunable terahertz (THz) metamaterial (TTM) with polarization-dependent sensing characteristic. The MEMS-based TTM device is reconfiguration by using two electrostatic comb-drive actuators, which exhibits tunable dual-band resonances in both transverse electric (TE) mode and transverse magnetic (TM) modes. The tuning ranges of free spectra ranges are 42 GHz and 82 GHz for TE and TM modes, respectively by increasing the gap between the left and right semicircle-shaped ring resonators. The electromagnetic responses of the proposed MEMS-based TTM device can be switched between dual-resonance and triple-resonance by changing the distance between the left and right semicircle-shaped ring resonators along y-axis direction. These results indicate MEMS-based TTM device shows polarization-sensitive and switching characteristics. MEMS-based TTM device is particularly sensitive to the environmental refraction index, and there is a linear relationship between the shift of resonant frequency and the change of refraction index. The sensitivity is 0.186 THz/RIU while the maximum figure of merit and quality factor reach 208 and 248, respectively at the first TE resonance. These outstanding and unique results of MEMS-based TTM device provide an effective approach for the design of highly linear and sensitive gas and environmental applications.

Design and Analysis of MIMO Dual Band Patch Antenna for 5G New Radio Applications in Mobile Terminals

This paper presents a dual-band MIMO antenna design with compact size for 5G communication under 6 GHz band frequency. The metallic monopole stub structure is used to miniaturization of antenna. The L-shape monopole antenna is modified by adding semi-circular element in radiating structure of monopole to obtain dual-band resonance. The High isolation is achieved by employing T-shaped stub in ground plane.It has compact size is 45 mm × 25 mm × 1.6 mm3. The proposed Dual Band MIMO antenna has been design on FR4 material with ɛr = 4.4 with 1.6 thickness. The proposed antenna has 5G application in the bands of 2.5 GHz (2.34 GHz-2.62 GHz) and 3.5 GHz (3.20 GHz-5.20 GHz). The bandwidth of antenna getting 320MHz and 2500MHz at 2.5GHz and 3.5GHz respectively. The Isolation (S21) of proposed antenna is -31.2 dB at 2.5 GHz and -19.5 dB at 3.5 GHz. VSWR is less than 1.06 for both the bands. The designed dual band MIMO antenna covers 5G bands of 2.3-2.4GHz (n30/n40), 2.4-2.5GHz (n7/n38/n41/n90), and 3.2-5.2GHz (n77/n78/n80). The experimental and simulated results observed good matching except some slight variation. This proposed dual band MIMO antenna is suitable for 5G mobile Communications.

Modified minkowski fractal multiband antenna with circular-shaped split-ring resonator for wireless applications

In this article, a modified Minkowski fractal antenna with a circular-shaped split-ring resonator (CSSRR) structure is proposed for wireless applications. Fractal geometry is accountable for creating dual-band resonance, and CSSRR is responsible for obtaining a middle resonance frequency band. The proposed antenna has a compact dimension of 23.5 × 26.5 × 1.6 mm3 to be fabricated and measured. Antenna iterations performed to achieve the desired frequency band. Antenna design has three resonance frequency bands at 2–2.7 GHz (700 MHz), 3.4–3.6 GHz (200 MHz) and 5.45–5.95 GHz (500 MHz), respectively. It can be used to cover 2.4/5 GHz wireless local area network (WLAN), 2.5/3.5 GHz wireless interoperability for microwave access (WiMAX), 2.1/2.3 GHz 3 generation (3G)/4 generation (4G) and 5.9 GHz safety applications. It is observed that the proposed antenna has good radiation characteristics in both E-plane and H-plane in the desired frequencies. Further, it has better antenna parameters than the various antenna designs reported in the literature.

Miniaturized dual stop band frequency selective surface with broadband linear co to cross polarization conversion ability

This work presents a miniaturized angularly stable frequency selective surface (FSS) on a single layer substrate. Unit cell comprises of convoluted circular rings connected cross dipole and linear arrow headed dipole printed on both sides of the substrate. A closely spaced dual stop band resonances are obtained at 10 and 14.3 GHz with frequency ratio of 1.43. FSS shows a − 10 dB stopband bandwidth (BW) from 7.32 to 11.05 GHz (40.61%) and 12.68 to 15.97 GHz (22.97%) with >30 dB stop band rejection at center frequencies. FSS poses the features of stable performance under change in polarization and angularly stable response up to 60° incident angle. Later the proposed FSS is printed on grounded thick dielectric substrate and it shows broadband reflection type co to cross polarization conversion from 7.2 to 17.32 GHz (82.54%) with polarization conversion ratio >80% and oblique angle stability up to 35°. To the best of authors' knowledge, this is the first time in literature a single unit cell geometry with two different properties, spatial filtering on transmission and polarization conversion on reflection have been designed and analyzed in details. A finite array with size 25 × 25 of the proposed FSS is fabricated and the measured filter response shows a good agreement with simulated performance at normal and oblique incidences. The proposed FSS is used as a reflector of a dual band monopole antenna and the simulation results shows gain improvement of 5.51 and 3.8 dB at the two stopband frequencies.

Miniature Dual Band Button Antenna Using Cylindrical Dielectric Resonator

This paper presents miniature dual-band cylindrical dielectric resonator antenna (CDRA) based on button antenna for wireless body area network (WBAN) applications. A button antenna is designed by stacking two CDRAs (low and high permittivity) fed by coaxial probe through the ground plane and penetrates the bottom CDRA. The prime contributions of using DRAs are to enhance the performance and to provide a compact size of antenna. However, the coaxial probe realizes two radiation patterns, monopole and broadside patterns. A comprehensive validation using CST microwave studio is carried out to determine the characteristics of the proposed button antenna. In addition, to ensure that the results are acceptable to the practitioner in this field, a prototype was fabricated and tested. The superiority of the proposed antenna is confirmed by possessing 39% more compact size compared to previously reported studies, efficiency of more than 63% and bandwidth of 4.9% and 6.6% for lower and upper band, respectively. This proposed design is a promising candidate to benefit on/off body communication devices operating at 2.4 and 5.6 GHz.

Investigation on dual‐band equilateral triangular shaped dielectric resonator antennas for WLAN applications

In this article, two configurations of dual-band equilateral triangular dielectric resonator antennas (ETDRAs) for WLAN applications are proposed namely, configuration-I and configuration-II. The configuration-I uses single ETDRA for dual-band operation; whereas, configuration-II includes two ETDRAs to operate as a dual-band antenna. Both the antenna configurations, which uses 99.7% alumina material having a dielectric constant of εr = 9.9, are excited to operate in the bands of 2.4 to 2.5 GHz and 5.75 to 5.85 GHz. The antennas are excited using a conventional coaxial feed to have a simple feeding mechanism. Prototypes of both the antenna configurations are fabricated and measured. The radiation characteristics of the antennas are discussed. The circuit analysis for the proposed configurations of the dual-band ETDRA is also performed and an appropriate equivalent circuit for each dual-band ETDRA is presented. Further, the performance of the proposed configurations of the dual-band antennas are also compared with other dual-band DRAs reported in the literature.

Engineering of dual-band magnetic dipole decay rate enhancement with concentric hollow nanodisk resonators

Abstract Unlike metal nanoparticles, the dielectric nanoparticles exhibit low-loss electric and magnetic Mie-type resonances. Thus, all-dielectric nanophotonics concept have been considered as the pathway to enable the key applications such as all-photonic quantum information processing. In this context, the efficient decay-rate-enhancement of spontaneous emission have gained interest with the aim of the development of nano light sources. However, due to the neglected interaction of the magnetic component of the light with the matter, the enhancement of the decay rate of the magnetic dipole emission have been ignored. Owing to the capability of efficiently concentrating the magnetic field into subwavelength scale via the Mie-type magnetic resonances, the dielectric nanoparticles such as hollow nanodisks have become intriguing for the magnetic Purcell effect or any optical-magnetism-related application with a demand of magnetic hotspot generation. However, all of the proposed dielectric nanoparticles are designed for single band enhancement which limits the potential of the applications. To overcome this limitation, a novel dielectric resonator architecture based on the nested hollow nanodisks is numerically demonstrated that exhibit dual-band magnetic dipole resonances in the visible and near-infrared range. First the scattering properties of the individual resonators are investigated. Additionally, the near field properties are presented via the field enhancement maps. Finally, the dual-band magnetic dipole decay rate enhancement properties and the dependence on the geometrical parameters are investigated. The results of this study may bring new possibilities to maximize magnetic dipole emission over a wide spectral range that covers visible and near-infrared for the applications such as nano light sources and integrated quantum information technology.

Dual band dielectric resonator antenna for high-speed applications

The antennas for wireless communication devices have undergone a tremendous expansion from the external monoband resonant antenna to the internal non-resonant multi-band antenna. In this paper, a dual-band dielectric resonator antenna for high-speed applications is proposed. Due to the complex edge-shaped boundary between the dielectric and air in a rectangular dielectric resonator antenna, a complex closed form of expression is difficult to achieve. To address this problem a half-cut cylinder is placed over the rectangular dielectric to achieve excellent radiation characteristics. This proposed antenna provides a wide dual-band response with fractional impedance bandwidth of 21.92% and 19.09%while operating from7.32 GHz to 9.12 GHz and 10.71 GHz to 12.95 GHz. It provides an average gain of 3dBi with high gain stability in the entire operating frequency band. The radiation efficiency is found to be 96% due to low ohmic and dielectric losses. The cross-polarization is around 20 dB lesser than the co-polarization. Its gain and directivity can further be enhanced by implementing serial and parallel array structures. This design uses HFSS 14.0 commercial electromagnetic simulation tools.

A circular microstrip patch antenna to operate in dual band for wireless communications

A dual band circular micro-strip patch antenna is designed and simulated to obtain electronic circuit miniaturization of an antenna in high speed wireless local area networks (IEEE 802.11a standard). The proposed antenna contains a substrate layer (FR-4 lossy) with a dielectric constant of 4.9 and there is a circular patch on the upper layer of the substrate. The coaxial probe feed is used to excite the desired antenna which reduces the spurious radiation and hence obtained good efficiency. Also the cavity model is used for larger bandwidth while maintaining the lower size of the antenna. An ‘E’ shaped slot is introduced in the radiating patch to obtain dual band resonance frequency with maximum current distribution on the surface. Finally the simulated results using Computer Simulation Technology (CST) microwave studio 2009 in this design are compared with manual computation results and are found to be suitable for WLAN applications.

Dual-band resonance induced broadband low-frequency radar absorber based on electric ring resonator embedded magnetic absorbing materials

Magnetic absorbing material (MAM) embedded with electric ring resonator (ERR) is demonstrated to broaden the absorbing bandwidth in low-frequency range. We obtained the relation between input impedance and absorption bandwidth under specific reflection threshold to verify the influence of the embedded ERRs on impedance matching characteristic. Numerical simulations were carried out and the results are in agreement with theoretical analysis. We investigated the absorption mechanism through analyzing the distributions of electric and magnetic fields. The incidence angle sensitivity under different polarization modes is also discussed. It is demonstrated that the MAM with embedded-ERR increased the bandwidth under −10 dB from 1.73–3.17 to 1.48–3.87 GHz and 1.47–4.07 GHz for the TE-incidence and TM-incidence, which is 1.66 and 1.81 times wider than that of MAM, respectively. The proposed structure could broaden the absorption bandwidth in low-frequency range by means of introducing dual-band resonance in a single-layer medium.

Dual Band CRLH Metal Antenna for WLAN Applications

A composite right/left handed (CRLH) metamaterial antenna is proposed in this paper. The antenna is designed for WLAN IEEE 802.11 standard; where bands 2.4 GHz usage frequency 2401–2495 MHz and 5 GHz usage frequency 5170–5875 MHz worldwide. A composite right left handed metamaterial has combined effect of right handed and left handed metamaterial and which creates dual band resonance in the antenna. By providing shorting pin loading at edge of the radiating metal, the left handed metamaterial property is created in the antenna. The antenna occupies rectangular area of 38.2 $$\times$$ 29.1 $${{\hbox {mm}}}^2$$ and 6 mm air gap from ground plane. The return loss of $$-10$$ dB is achieved over the bandwidth with promising peak gain of 2.3 dBi and 8.6 dBi for 2.4 GHz and 5 GHz band, respectively. The antenna is fabricated, and measured values are closely matching with simulation results. The proposed antenna has orthogonal radiation patterns and maximum efficiency of 84.2% and 90.3% for dual frequencies.

Synthesis Design on Wideband Single-Ended and Differential Dual-Band Filtering Impedance Transformer

In this brief, a novel dual-band wideband impedance transformer (IT) integrated with the function of dual-band bandpass filtering was proposed for the first time. The presented design, based on the equivalents of dual-band J-inverters and LC resonators, has a simple structure with parallel open/short-circuited stubs and cascading transmission lines. Analysis results show that the considered ITs can work at two separate uncorrelated frequency bands with arbitrary terminated real impedances. For demonstration, a wideband single-ended dual-band filtering impedance transformer (DBFIT) with the filtering order n = 4, and a differential DBFIT with n = 3, are designed. In particular, the common-mode rejection of the differential circuit is well considered. The simulated and measured results are recorded in good agreement, well verifying the design concept.

High-Gain SIR Dual-Band Antenna Based on CSRR-Enhanced SIW for 2.4/5.2/5.8 GHz WLAN

This paper presents a dual-band step impedance resonator (SIR) antenna based on metamaterial-inspired periodic structure of coupled complementary split-ring resonators substrate-integrated waveguide (CSRR-SIW). The antenna supports wireless local area networks (WLAN) bands at 2.4/5.2/5.8 GHz. The CSRRs and two branches of the SIR element are etched on the top and bottom metal surfaces of the substrate. The SIR element produces a fundamental frequency f1 at 2.4 GHz and a second harmonic frequency fs2 at 5.7 GHz. Meanwhile, the CSRRs produces a resonant frequency at high-frequency band around 5.2 GHz, which can be combined with the second harmonic frequency fs2 at 5.7 GHz. The high-frequency bandwidth can then be broadened. The simulated and measured results show that the dual operation bands with bandwidths of 16% from 2.25 GHz to 2.64 GHz and 18.2% from 5 GHz to 6 GHz for |S11| < −10 dB are achieved. Meanwhile, the proposed antenna has peak gains ranging from 6.5 dBi to 7 dBi and from 7 dBi to 7.7 dBi in the lower and upper bands, respectively. Compared with many previously reported dual-band antenna designs, the proposed antenna achieves comparable bandwidth performance and larger gain per unit area with a relatively smaller size. Moreover, the simple structure renders the proposed antenna has the advantage of easy-processable and cost-effective implementation.

Reconfigurable Multiband Terahertz Metamaterial Using Triple-Cantilevers Resonator Array

We propose reconfigurable metamaterials with multiband resonance in the terahertz (THz) frequency range. By modifying the pattern width and gap of metamaterial, these designs exhibit the characteristics of polarization-dependence, dual-band resonance, and triple-band resonance. Two cantilever metamaterial (CM) devices are demonstrated by using micro-electro-mechanical system (MEMS) based bimorph cantilevers array, which can be deflected toward the out-of-plane direction. The measured transmission spectra are greatly agreed well with the simulation results. By applying different direct current (DC) bias voltages, the bending degree and electromagnetic response of CM device could be controlled. The multiband resonance can be tuned in the range of 0.33 THz by applying a DC bias voltage of 30 volts. The relationship of the resonant shifts and the applied DC bias voltages is quite linear, which can assist the device to be more controllable and applied in more fields. Such designs are promising to be used in various applications, such as frequency-selective detectors, multispectra imagers, and multifunctional switches in the THz frequency range. [2020-0236]

Tunable Terahertz Metamaterial Using an Electric Split-Ring Resonator with Polarization-Sensitive Characteristic

We present a tunable terahertz (THz) metamaterial using an electric split-ring resonator (eSRR), which exhibits polarization-sensitive characteristics. The proposed eSRR is composed of double symmetrical semicircles and two central metal bars. By changing the lengths of two metal bars, the electromagnetic responses can be tuned and switched between dual-band and triple-band resonances in transverse magnetic (TM) mode. Furthermore, by moving the bottom metal bar to change the gap between the two metal bars, the first resonance is stable at 0.39 THz, and the second resonance is gradually blue-shifted from 0.83 to 1.33 THz. The tuning range is 0.50 THz. This means that the free spectrum ranges (FSR) could be broadened by 0.50 THz. This proposed device exhibits a dual-/triple-band switch, tunable filter, tunable FSR and polarization-dependent characteristics. It provides an effective approach to perform tunable polarizer, sensor, switch, filter and other optoelectronics in THz-wave applications.

Concept and analysis of a coupled split-ring resonator for wide-/dual bands, self-filtering, high out-of-band suppression and highly efficient antennas

AbstractAn inspired metamaterial-based highly efficient monopole antenna displaying wide-/dual-band resonances along with self-filtering properties is presented. The monopole has high out-of-band suppression characteristics that lead to very close to 0 dB band-stop between the antenna dual resonant bands. The antenna operates at the two WLAN services of 2.65–3.25 and 5–7 GHz with stopband with total reflection at 4.5 GHz. The designed filtering characteristics are based on current coupling for the dual-band functions and current neutralization for the stopband function. Moreover, the proposed antenna has a very high radiation efficiency of 97 and 99% at 3 and 6 GHz, respectively. Furthermore, the proposed antenna exhibits an omni-directional radiation pattern with coplanar waveguide feed for simple integration with passive/active devices. Moreover, the antenna properties are achieved with a compact antenna size (30 × 30 mm2). With all presented results, the proposed antenna is very competitive over recent relevant antennas. In addition, a very good agreement between theoretical, full-wave simulations and measurements is achieved.

Dual-band microwave resonators based on cross hollow structures for refractive index sensing

We numerically and experimentally studied the electromagnetic characteristics of a suitably designed planar metamaterial which composed of cross hollow structures. The results show that two sharp transmission dips with quality factors of 7.93 and 19.3 can be generated in the microwave region under the excitation of normal incident electromagnetic wave. And if its surface is covered by 2 mm thick analyte, both of the two transmission dips show linearly spectral shift with the change of the analytes’ refractive index. Using the two resonances as the identifiers, the calculated average refractive index sensitivities are 1.116 GHz/refractive index unit (RIU) and 2.357 GHz/RIU, with corresponding figure of merits (FOM) of 1.87 and 4.9. It offers a potential for sensing detection and provides a reliable reference for the design of excellent plasmonic sensors.

Dual‐band dielectric resonator antenna with multi‐frequency circular polarisation

A dual-band rectangular dielectric resonator (DR) antenna is implemented with a multi-frequency circularly polarised (CP) response. The wide dual-band response is achieved by inserting the slots in the DR. The insertion of slots in the DR in a specific manner generates the orthogonal degenerate modes. Consequently, the multi-frequency CP response is obtained. The antenna provides the total overlapping CP bandwidth of 4.96% (13.36–14.04 GHz) in the lower band and 3.28% (14.95–15.45 GHz), 9.624% (17.11–18.84 GHz) and 0.517% (19.28–19.38 GHz) in the upper band. The antenna provides the 10 dB impedance bandwidth of 6.44% (13.36–14.25GHz) and 28.89% (14.95–20GHz) in the lower and upper bands, respectively. The peak gain of antenna remains >3 dBic in the passbands.