Dual-band Behavior Research Articles

Miniaturization of a patch antenna using circular reactive impedance substrate

In this article, to construct a reactive impedance substrate, unit ring is designed and proposed with radial and concentric mode analysis. A cylindrical substrate backed with a PEC plane and circular metallic elements on the top is used for achieving reactive surface impedance behavior. In this aspect, three unit rings structure with different ring elements are designed and simulated to realize the reflection phase characteristics. Afterwards, a probe-fed circular patch antenna is miniaturized by stacking the three-ring circular reactive impedance surface. The fundamental resonance frequency of the proposed antenna is reduced by about 30% with an improvement in impedance bandwidth by 121.6%. An improved front-to-back ratio as well as an acceptable co-pol and cross-pol isolation is exhibited in both E-plane and H-plane at the resonance frequency. In addition of miniaturization, dual band behavior has also been observed in the proposed design. Both resonance phenomena have been explained by circuit model representation and surface current distribution analysis. Improved radiation efficiency at 81.5% has been measured for the proposed antenna configuration.

Ultrabroadband Antenna With Robustness to Body Detuning for 4G Eyewear Devices

An ultrabroadband antenna design for 4G cellular coverage in eyewear devices is presented in this letter. The antenna has been designed considering a realistic eyewear printed circuit board and its dielectric frame. In order to overcome any negative effects from the antenna's surroundings (frequency detuning due to the head and the hand of the user), the antenna was designed and optimized to cover continuously the 700–2700-MHz band with a reflection coefficient below –6 dB instead of a dual-band behavior usually required for 4G operation: 700–960 and 1700–2700 MHz. The antenna was of capacitive coupling element type with its appropriate matching network to cover the mentioned frequency interval. To emulate a realistic device, an ABS plastic dielectric frame was manufactured using 3-D printing technology. The antenna was simulated and tested in three different use cases as “default case with user's head,” “with head and hand,” and “free space” cases. State-of-the art performance is demonstrated. The specific absorption rate behavior was also investigated through simulations and measurements to check the compliance with regulations.

Polarization insensitive plasmonic perfect absorber with coupled antisymmetric nanorod array

Plasmonic perfect absorbers have a large potential for biomolecular sensing applications such as refractometric biosensing and surface enhanced spectroscopy due to their high near-field enhancement and near-unity absorption capabilities. Despite these properties, novel plasmonic perfect absorbers with additional features are highly needed for real-world sensing applications. In this context, we present the design, characterization and experimental realization of a subwavelength plasmonic perfect absorber array with crucial properties including the dual-band absorption, high near-field enhancement with a large number of hot-spots, mass-production compatible design, high sensitivity, and polarization independency for both narrow and wide resonance bands. In order to investigate the spectral characteristics and to obtain a fine-tuning mechanism, we perform several numerical analyses by using finite difference time domain method. We also investigate the charge and current density distributions at the corresponding resonances. It is observed that the physical origin of the dual-band behavior is based on the dipolar plasmonic resonance of the horizontal nanorods and the plasmonic coupling mechanism of the structure. Furthermore, we investigate the sensing performance of the proposed device by calculating the refractive index sensitivity and figure-of-merit for the resonant modes by embedding it into different cladding media with various refractive indices. Finally, in order to demonstrate the potential of the proposed plasmonic perfect absorber for surface enhanced infrared absorption spectroscopy, we simulate the detection of carbonyl v(CO) stretching mode of a conformal poly(methyl methacrylate) layer. Due to its highly desired properties, the proposed device can be a good candidate for biomolecular sensing applications and also the results of our investigation can be useful for the further designs of plasmonic based sensors.

Reconfigurable circularly polarized capacitive coupled microstrip antenna

The design and measurement of reconfigurable circularly polarized capacitive fed microstrip antenna are presented. Small isosceles right angle triangular sections are removed from diagonally opposite corners for the generation of circular polarization (CP) of axial ratio bandwidth of 11.1%. Horizontal slits of different lengths are inserted at the edges of the truncated patch to provide the dual-band CP and by switching PIN diodes across the slits ON and OFF, reconfigurable circularly polarized antenna is realized. The antenna shows dual-band behavior with reconfigurable CP. In order to enhance the operation bandwidth of the antenna, an inclined slot was embedded on the patch along with PIN diodes across the horizontal slits. This proposed antenna gave an impedance bandwidth of 66.61% (ON state) ranging from 4.42 to 8.80 GHz and 68.42% (OFF state) ranging from 4.12 to 8.91 GHz and exhibits dual-frequency CP with PIN diode in OFF state and single-frequency CP with PIN diode in ON state with good axial ratio bandwidth. The axial ratio bandwidth of 4.42, 2.35, and 2.72% is obtained from the antenna. The antenna has a similar radiation pattern in all the three different CP bands and almost constant gain within the bands of CP operation.

Independently controllable dual-band microstrip bandpass filter using quadruple-mode stub-loaded resonator

In this article, a quadruple-mode stub-loaded resonator (QM-SLR) is introduced and its four modes are excited using a simple approach, which can provide a dual-band behavior. By changing the length of the loaded stubs, independently tunable transmission characteristics of the proposed quadruple-mode stub-loaded resonator were extensively described for filter design. Moreover, microwave varactors were adopted to represent the length variation of the loaded stubs for the dual-band tunability. The equivalent circuit modeling of the open stub with microwave varactor was given and discussed. Then, adopting the compact quadruple-mode stub-loaded resonator with three varactors, an independently controllable dual-band bandpass filter (BPF) was designed, analyzed, and fabricated. Its separated bandwidths and transmission zeros can be tuned independently by changing the applying voltage of the microwave varactors. A good agreement between simulated and measured results verified the design methodology. The proposed filter possesses compact size, simple structure, and excellent dual-band performances. © 2016 Wiley Periodicals, Inc. Int J RF and Microwave CAE 26:602–608, 2016.

Short dual‐band planar leaky‐wave antenna with broadside effect mitigation

In this contribution, a planar leaky-wave antenna capable of dual-band frequency scanning including broadside is presented. It is based on the complementary strip-slot element, which is a microstrip-fed slot with ultra broad impedance bandwidth, achieved by introducing its complementary stub on the layer of the microstrip. The mitigation of the broadside degradation is accomplished by properly designing the strip-slot and the pitch of the array and by introducing asymmetry (misalignment) in the unit-cell. The resulting structure differs from previous proposals in the broadband element on which it is based, which allows dual-band behaviour and high efficiency with an array of just five elements.

Smith Chart-based Design of a Dual Band Real Impedance Matching Network

ABSTRACTThis paper presents a Smith chart-based methodology for designing a dual band real impedance matching network. The focus is to depict the dual band behavior using Smith chart, giving a better insight into analytical equations thus derived. To validate the design methodology, a dual band 3dB Wilkinson power divider is designed at two frequencies i.e. 0.9 GHz and 2.45 GHz. Summary of the derived equations and a generic MATLAB code is appended, as a quick design tool.

A Compact Zeroth-Order Resonating Wideband Antenna With Dual-Band Characteristics

In this letter, a compact zeroth-order resonating wideband antenna with dual-band characteristics is designed using composite metamaterial (MTM). Such composite MTM consists of patch with series gap, meander line inductor, and a radial stub. The proposed structure offers compact size with radiating element dimensions of $0.08{\lambda _o} \times 0.122{\lambda _o} \times 0.006{\lambda _o}$ . The proposed MTM antenna exhibits dual-band behavior with first band centered at 1.22 GHz while other band is centered at 3.97 GHz with an impedance bandwidth ( ${{\rm S}_{11}} ) of 5% and 59.9%, respectively. The proposed structure shows good radiation characteristics with an average peak gain of 1.82 dB and 2.15 dB for first and second band, respectively. The radiation patterns are consistent throughout the working band. The prototype structure has been fabricated and experimentally validated.

A DUMBBELL-SHAPED DUAL-BAND METAMATERIAL ANTENNA USING FDTD TECHNIQUE

In this study, a dumbbell-shaped metamaterial (MTM) antenna has been proposed for dual-band applications using finite difference time domain (FDTD) technique. Such a composite MTM antenna consists of dumbbell-shaped patch, microstrip and partial ground plane. The proposed antenna shows dual-band behavior having impedance bandwidths (|S11| < −10 dB) of 28.5% and 8.7% at 1.72 GHz and 3 GHz respectively. It has been designed to operate at various cellular standards such as GPS, GSM1800 and WCDMA. Design and analysis have been carried out using FDTD code based on uniform meshing and convolutional perfectly matched layer (CPML) absorbing boundary conditions. Further, simulation results have been verified using HFSS, and a prototype has been fabricated to validate the results experimentally. The overall electrical size of the proposed antenna is 0.287λo × 0.346λo × 0.009λo. The proposed dual-band antenna offers excellent radiation characteristics with a gain of 1.2 dBi and 1.5 dBi at 1.72 GHz and 3 GHz respectively with omnidirectional radiation patterns in xz -plane.

Cantor fractal-based printed slot antenna for dual-band wireless applications

Fractal geometries are attractive for antenna designers seeking antennas with compact size and multiband resonant behavior. This paper presents the design of a new microstrip-fed printed slot antenna for use in dual-band wireless applications. The slot structure of the proposed antenna is in the form of Cantor square fractal geometry of the second iteration. The slot structure has been etched on the ground plane of a substrate with relative permittivity of 4.4 and 1.6 mm in thickness. A parametric study is conducted to explore the effects of some geometrical parameters on the antenna performance. Results show that the antenna possesses a dual-band behavior with a wide range of resonant frequency ratio. In addition to the ease of fabrication and simple design procedure, the antenna offers desirable radiation characteristics. A prototype of the proposed antenna has been simulated, fabricated, and measured. The measured 10 dB return loss bandwidths for the lower and the upper resonant bands are 42% (2.35–3.61 GHz) and 20% (5.15–6.25 GHz), respectively. This makes the proposed antenna suitable to cover a number of operating bands of wireless systems (2.4 GHz-Bluetooth, 2.4 GHz ISM, 2.4/5.8 GHz-WLAN, 3.5 GHz-WiMAX, and 5.8 GHz-ITS).

Quad-Band Bandpass Filter Using Quad-Mode Stub-loaded Resonators

Compact multi-band bandpass filters using quad-mode stub-loaded resonators are proposed in this letter. Firstly, a novel approach about the mode-splitting characteristics of the quadruple-mode resonator is investigated, which can provide dual-band behavior. Secondly, a quad-band filter is proposed and designed by cascading two quadruple-mode resonators; the upper one operates at 1.8/2.4 GHz (GSM- and WiMax-band) and the lower one at 1.57/2.1 GHz (GPS- and WCDMA-band). Finally, the proposed filters have been fabricated. Respectable agreement between simulation and measurement verifies the validity of this design methodology.

COMPACT QUASI SELF-COMPLEMENTARY ELLIPTICAL DISC MONOPOLE ANTENNA WITH TAPERED MICROSTRIP FEED LINE

In this paper a compact elliptical disc monopole antenna with tapered microstrip feed line for UWB application is proposed. The antenna is designed using the quasi self -complementary technique for attaining electrical as well as physical size reduction. A triangular notch is included in the ground plane for impedance matching between the antenna and the RF front end. The adoption of this miniaturization technique has narrowed the impedance bandwidth of the antenna in the UWB range but lead to an additional operating bandwidth in Ku band thereby exhibiting dual band behavior. This reduction in the bandwidth in the UWB range was overcome by using the tapered microstrip feed line configuration. The antenna exhibited a wide impedance bandwidth extending beyond the UWB range and hence could be used for both UWB as well as Ku band applications. The antenna has a physical dimension of 16mm X 25mm corresponding to an electrical size of 0.24λ and was designed on an FR4 substrate with er of 4.7. It is seen that the antenna proposed here has led to 62% size reduction with a percentage impedance bandwidth of 123.46% when compared with the conventional elliptical disc monopole antenna.

Compact Dual-Band Differential Power Splitter With Common-Mode Suppression and Filtering Capability Based on Differential-Mode Composite Right/Left-Handed Transmission-Line Metamaterials

This letter presents a compact differential-mode (balanced) power splitter with filtering capability and dual-band functionality. This multifunctional device is based on differential-mode composite right/left-handed (DM-CRLH) transmission lines specifically designed to achieve the dual-band behavior and to suppress the common-mode noise over a broad frequency band. The DM-CRLH lines are implemented by means of pairs of CRLH lines with series connected interdigital capacitors and strip inductors in the series branches and mirrored step impedance resonators (SIRs) in the shunt branches. For the differential mode, the SIRs are described by parallel resonant tanks, and the resulting equivalent circuit model is the canonical circuit of a CRLH line, which can be used for designing the dual-band balanced splitter/filter. However, the SIRs are opened under common-mode operation, introducing transmission zeros for that mode. By tailoring the position of these transmission zeros, the common mode can be effectively rejected over a frequency band that covers the splitter operating frequencies. The fabricated dual-band balanced power splitter exhibits a measured matching level better than -11 dB, and measured insertion losses (power splitting) lower than 4.1 dB at the design frequencies ( f1=1.8 GHz and f2=2.4 GHz). The common-mode suppression at f1 and f2 is better than 30 dB.

Complementary Sierpinski gasket fractal antenna for dual-band WiMAX/WLAN (3.5/5.8 GHz) applications

A proximity-fed complementary Sierpinski gasket fractal with equilateral triangular shape resonator in multilayer structure to achieve dual-band behavior for WiMAX and WLAN applications has been proposed. An electromagnetic coupled stacked structure of two different patches operating at two frequencies (3.5 GHz WiMAX and 5.8 GHz wireless LAN) has been designed for dual-band wireless applications. Proposed antenna was simulated using CST Microwave Studio based on the finite integration technique (FIT) with perfect boundary approximation (PBA). Finally, the proposed antenna was fabricated and some performance parameters were measured to validate against simulation results. The design procedures and employed tuning techniques to achieve the desired performance are presented.

Bandwidth Enhancement of Pin Shorted Triangular Patch Antenna with Circular Notch

This paper presents the notch loading effect on the pin shorted equilateral triangular shaped microstrip antenna (ETMSA). The proposed antenna shows the dual band behavior due to pin shorting and also the effect of circular notch for bandwidth enhancement, with dual shorting pin. The proposed antenna providing enhanced impedance bandwidth of 13.42%.Also effect of different dielectric on the bandwidth performance has been studied. All the results have been carried out using MOM based IE3D simulation.

Dual-Band Matching Properties of the C-Section All-Pass Network

The all-pass C-section is introduced as a replacement for the classic quarter-wave section in the design of wideband dual-band impedance-matching networks. First, the impedance-matching properties of the all-pass C-section are presented, showing its dual-band behavior. Second, a simple adaptation to dual-band designs of the well-known wideband designs with binomial and Chebyshev responses is introduced. Finally, a dual-band power divider is presented, as a test of the introduced design technique.

Microwave Transmission Through an Array of Ring Slots in a Metal Sheet Capped With Concentric Metal Rings

The resonant transmission response of an array of ring slots in a metal sheet, capped with concentric copper rings (annuli) is explored both experimentally and numerically. This frequency selective surface (FSS) shows dual pass band behavior due to two resonances associated with two annular resonant spaces (annular cavities). One is formed between the outer edge of the annulus and the metal beyond the outer circumference of the ring slot, and the other is formed between the inner edge of the annulus, and the inner circumference of the ring slot. The experimental results are in agreement with finite element method (FEM) modeling predictions. Using the same modeling, the behavior of multi pass band structures using a series of concentric copper annuli over a similar series of concentric annular slots in a ground plane is also explored.

A Novel Compact Dual-band Slot Antenna

This paper introduces a compact dual-band slot antenna using spiral inductive loaded resonators. The radiating elements of the proposed antenna are composed of two balanced short circuited slot lines. To design a dual-band antenna, the microstrip feed line is somehow implemented to provide three short circuit points between the antenna and the feed lines. The antenna size is very compact, and can be integrated easily with other RF front-end circuits for dual-band applications. It is demonstrated that the proposed antenna can provide dual-band behavior with satisfactory radiation characteristics.

A simple printed dipole antenna with dual-band behavior

This paper reports a simple printed dipole antenna which exhibits dual-band operations.The antenna's radiation pattern is bidirectional in the x–y plane and close-to-omnidirectional in the x–z plane. The 10 dB impedance bandwidths achieved are 38.6% and 4.7% centered at 1.1 and 2.3 GHz, respectively. The impedance and radiation characteristics of the proposed antenna, as studied by both simulation and experiment, are satisfactory. The antenna's performance compares well with that of a recently proposed dipole antenna with fractal shape. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26226

A tunable dual band notch on a UWB printed slot monopole antenna by using open circuit stubs

A new printed wide slot antenna with single- and dual-band notch behavior is presented. The base of antenna is a simple fork-shaped radiating patch, which covers the ultra-wideband (UWB) frequency range. By using additional protrudent open circuit stubs on the base patch, multiband notch behavior is obtained. Effects of varying the added stubs parameters on the antenna performance show that the center frequency of band rejections can be finely tuned. The proposed dual-band notch antenna covers 2.4–10 GHz with two bands rejection for WiMAX (3.3–3.9 GHz) and WLAN (5.7–6 GHz) bands. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26095