Dual-band Behavior Research Articles

A flexible dual-band 4 × 4 MIMO antenna for 5G mm-wave 28/38 GHz wearable applications

This paper presents a novel, dual-band, four-port multi-input–multi-output (MIMO) antenna for 28/38 GHz millimeter wave 5G wearable applications. In the proposed work, we have used a novel design approach to get the dual-band behavior from a MIMO design with a small footprint of 18 × 8.5 × 0.25 mm3. For this purpose, each MIMO element is designed as a composite form of a circular and elliptical structure connected with a narrow strip and fed by a tapered feedline. The peak realized gains and total efficiencies of the antenna, evaluated in free space, are 4.15 dBi, 7.73 dBi and 80.13%, 85.44% at 28 GHz and 38 GHz frequencies, respectively. To appraise the thorough behavior of the MIMO antenna, we have evaluated all the parameters of the antenna: Envelope Correlation Coefficient (ECC), Diversity Gain (DG), Mean Effective Gain (MEG), Channel Capacity Loss (CCL), and Total Active Reflection Coefficient (TARC), and found them satisfactory. Channel capacity of the antenna at SNR = 20 dB is found to be 21.61 bps/Hz. For wearable applications, the proposed 4-port MIMO antenna is designed on a flexible Rogers 3003 substrate, and the performance is checked by evaluating bending analysis. The safety of the antenna is verified by analyzing the 1 g/10 g SAR at 28/38 GHz and the corresponding average SAR values are 0.11/0.08 W/kg and 0.05/0.04 W/kg, respectively. All the average SAR values for the proposed MIMO antenna are within the acceptable limits according to FCC/ICNIRP standards.

Dual-Band 2 × 1 Monopole Antenna Array and Its MIMO Configuration for WiMAX, Sub-6 GHz, and Sub-7 GHz Applications

This study introduces a cost-effective monopole antenna array and its MIMO configuration. The single element consists of a rectangular patch monopole featuring five circular slots at the center, accompanied by two thin slots at the top, offering a wide bandwidth (2–7.62 GHz) and a peak gain of 3.8 dBi. For gain improvement, a 2 × 1 antenna array is demonstrated. This antenna array exhibits dual-band behavior; spans from 2 to 3.71 GHz and from 5.9 to 7.54 GHz; covers the 2.5 GHz band (2.3–2.7 GHz), a significant portion of the n78 band (3.3–3.71 GHz), and the n96 band (5.925–7.125 GHz); and is assigned to WiMAX, sub-6 GHz, and sub-7 GHz applications, respectively. The antenna array achieves a peak gain of 6.47 dBi. Lastly, a two-element MIMO configuration derived from the 2 × 1 array is designed. Implementing a defected ground structure (DGS) on the ground plane plays a crucial role in enhancing the isolation from 7 dB to 20 dB. The presented MIMO antenna covers the desired frequency bands of 2.5 GHz, n78, and n96 with a peak gain of 7.5 dBi and high radiation efficiency (<99%), which qualifies it for WiMAX, sub-6 GHz, and sub-7 GHz applications.

A dual-band MIMO PIFA antenna with a printed rectangular open-ended ring for 5G/WLAN mobile terminal

A dual-band 8 × 8 multiple-input-multiple-output (MIMO) PIFA antenna that operates in the sub-6 GHz spectrum for 5G and WLAN mobile terminals is presented. The eight elements of the MIMO antenna are formed by using an L-slotted PIFA antenna, an L-shaped parasitic element, and a 2D rectangular open-ended ring parasitic structure that is printed next to the L-shaped parasitic element. In this article, we first proposed an ultra-thick PIFA antenna element to work in the 3.4-3.8 GHz 5G band and the 5.15-5.85 GHz WLAN band, adopting a new method that can provide dual-band behavior with wide bandwidth. Then, the final antenna element is used to design an eight-port MIMO antenna system, and the results show good MIMO performance in terms of envelope correlation coefficient (ECC), diversity gain (DG), mean effective gain (MEG), and multiplexing efficiency (ME).

Circularly polarized global navigation satellite systems metasurface antennas in sub-wavelength metallic cavities

AbstractTwo metasurface-inspired antennas embedded in a metallic cavity are introduced here. They are expected to be integrated on fast moving platforms enduring harsh accelerations and shocks. The metasurface allows enlarging the antenna bandwidth that is intrinsically reduced for small antennas embedded in sub-wavelength metallic cavities. The first one is only 60 × 60 × 20 mm3 (0.23λ1 × 0.23λ1 × 0.08λ1 at the frequency of 1164 MHz) and presents a dual-band behavior, covering both the lower and upper global navigation satellite systems (GNSS) bands (all GNSS bands are covered). It is fed by four probes and a dedicated circuit, ensuring the phase quadrature between adjacent feeds to achieve circular polarization over these two bands. For the second proposed antenna, circular polarization is achieved using two feed points connected to the radiating aperture of size 50 × 50 × 20 mm3 (0.26λ0 × 0.26λ0 × 0.10λ0 at the frequency of 1559 MHz). It covers the E1, L1, B1, and G1 GNSS bands. The numerical results are successfully validated by measurements.

Balanced single/dual band trisection filters

ABSTRACT This work presents balanced microstrip filters with asymmetrical frequency response based on a balanced trisection topology. The proposed balanced trisection topology has the feature of being used in single and multiband microwave filters. In this work, in order to test the topology flexibility, we address two applications, one for a single-band filter and the other for a dual-band filter. This topology introduces TZs on either side of the passband edges, improving the selectivity on one side of the passband. The non-adjacent resonators of the single-band trisection balanced filter are based on a Pi-network balanced resonator which is composed by six transmission lines (TLs) and two inductors (Ls). The differential-mode (DM) and common-mode (CM) resonances can be chosen independently with a proper selection of the impedances and the electrical lengths of TLs in order to have high DM stopband and intrinsic high common mode rejection (CMR). The Pi-network was modified and analyzed under the even and odd mode technique to have a dual-band behavior. Good agreement between simulation and measurement was achieved.

A Miniaturized Dual-Band Short-Ended ZOR Antenna with Backed Ground Plane for Improved Bandwidth and Radiation Efficiency

This paper presents a miniaturized planar dual-band short-ended metamaterial antenna with the backed ground plane to improve antenna bandwidths and radiation characteristics. The proposed dual-band metamaterial (MTM) antenna has been made up of the composite right- or left-handed transmission line (CRLH-TL) concept. Here, the backed ground plane has been employed to generate an extra coupling capacitance (CC), which shifts the ZOR frequency in the lower band while also improving ZOR matching and increasing the impedance bandwidth of the higher-order mode. In this proposed MTM antenna, interdigital capacitance (IDC) has been used in place of a simple series gap, which shifts the higher-order impedance bandwidth into a lower frequency band for second-band Wi-MAX applications (3.3–3.7 GHz). The proposed antenna offers a short-ended MTM, and hence the ZOR frequency is controlled by a series of LC lumped parameters. The proposed antenna offers dual-band behavior with measured −10 dB impedance bandwidths of 5.55% and 41.57% at centered frequencies of 2.70 GHz and 4.33 GHz, respectively. The overall electrical size of the designed antenna is 0.225λ0 × 0.144λ0 × 0.0144λ0 at ZOR (f0 = 2.70 GHz), where λ0 is the free space wavelength; therefore, it is applicable for different Wi-MAX application bands (2.5–2.7 GHz/3.3–3.8 GHz). Furthermore, the proposed dual-band MTM antenna provides compactness, low loss, stable gain, and radiation efficiency, and also offers omnidirectional radiation patterns in the E-plane and dipolar type radiation patterns in the H-plane, respectively.

Dual-Band CPW Graphene Antenna for Smart Cities and IoT Applications.

In this paper, a dual-band graphene coplanar waveguide antenna is designed for smart cities and internet of things applications. A graphene film is chosen as the conductive material for the radiation patches and ground plane with a thickness of 240 μm and an electric conductivity of 3.5 × 105 S/m. The dielectric is glass with a dielectric permittivity of 6 and a thickness of 2 mm. The implementation of the antenna on glass permits the integration of the antenna in smart cities and IoT applications. This antenna is based on two trapezoidal patches that generate the dual-band behavior. The overall dimensions of the antenna are 30 mm × 30 mm × 2 mm. The reflection coefficient, gain, and radiation patterns were measured and compared with the simulations. The antenna covers two frequency bands; the lower band covers the 2.45 GHz ISM band, and the upper band range covers from 4 to 7 GHz.

Non-Invasive Microwave Hyperthermia and Simultaneous Temperature Monitoring with a Single Theranostic Applicator.

Cancer therapies are constantly evolving. Currently, heating tumor tissue is becoming more accessible as a stand-alone method or in combination with other therapies. Due to its multiple advantages over other heating mechanisms, microwave hyperthermia has recently gained a lot of traction. In this work, we present a complementary split-ring resonator that is simultaneously excited in two independent frequency bands. With a high-power signal, the applicator is excited and heats the tissue-under-test up to 50°C with an average heating rate of 0.72°C per second. Furthermore, we present a dielectric temperature control system using the same applicator for microwave hyperthermia applications, which currently still requires an additional thermometry system. By exciting the applicator with a low-power signal, we can constantly monitor its resonant frequency. This resonant frequency depends on the tissue properties, which in turn are temperature-dependent. In the temperature range from 20-50°C, a positive correlation between the temperature and resonant frequency was established.Clinical relevance - Exploiting the dual-band behavior of the complementary split-ring resonator to heat the tissue-under-test while dielectrically monitoring its temperature, creates new possibilities towards a theranostic, non-invasive microwave hyperthermia applicator.

A Novel Analytical Design Technique for a Wideband Wilkinson Power Divider Using Dual-Band Topology.

In this paper, a novel analytical design technique is presented to implement a coupled-line wideband Wilkinson power divider (WPD). The configuration of the WPD is comprised of three distinct coupled-line and three isolation resistors. A comprehensive theoretical analysis is conducted to arrive at a set of completely new and rigorous design equations utilizing the dual-band behavior of commensurate transmission lines. Further, the corresponding S-parameters equations are also derived, which determine the wideband capability of the proposed WPD. To validate the proposed design concept, a prototype working at the resonance frequencies of 0.9 GHz and 1.8 GHz is designed and fabricated using 60 mils thick Rogers’ RO4003C substrate. The measured result of the fabricated prototype exhibits an excellent input return loss > 16.4 dB, output return loss > 15 dB, insertion loss < 3.30 dB and a remarkable isolation > 22 dB within the band and with a 15 dB and 10 dB references provide a fractional bandwidth of 110% and 141%, respectively.

Four element three‐dimensional SIW horn antenna array for high‐frequency applications

A low-profile three-dimensional substrate integrated waveguide (SIW) horn antenna array with its novel feeding structure is proposed in this article. The feeding element is capable of transforming the wave from one plane to its orthogonal plane. Such type of three-dimensional SIW, H-plane horn antenna design is not available in the existing literature. The design is proposed to provide high gain for radar, 5G, and satellite communication applications. The single SIW horn antenna does not have significant gain at the desired frequencies. When the antenna element is loaded with dielectric the gain improves by 1.4 dB. The antenna elements are further arranged in a box shape, forming a three-dimensional array, which improves the gain significantly. Such structure shows dual band characteristics and provides gain of 11.3 dB at 28.26 GHz and 9.64 dB at 29.41 GHz. The same three-dimensional design when loaded with dielectric at the aperture end also show a dual band behavior and improve the gain further to 12.5 dB at 28.12 GHz and 12.55 dB at 29.28 GHz. The proposed three-dimensional antenna designs are compared to four element linear array designs, and it shows substantial improvement in gain for the desired frequency.

Dual Band Octagonal Microstrip Patch Antenna Loaded with Array of Split Ring Resonators

This article presents a proposal about an octagonal microstrip patch antenna (MPA) loaded with Split Ring Resonators (SRR) the antenna’s ground part. The antenna size reduction using multiband radiators will suits for miniaturization of day-to-day handheld devices. The dual band behaviour of the antenna will integrate more communication standard in one system which saves the installation space in the device. In this context, an octagonal antenna structure is conceived for a dual operational frequency of 5.63 GHz and 5.97 GHz. Hereby, a Co-planar Waveguide (CPW) structure is adapted to the octagonal patch and the structure has been observed by simulation analysis under HFSS platform. The overall geometry of the antenna is 30 x 26 x 1.6 mm3. The antenna feed using a microstrip for earning a better impedance matching between the antenna and transmission line. The antenna design provides a wider bandwidth of 580MHz and average gain of 3.25 dBm. The attainment of dual band operational frequencies is due to the CPW and SRR structure in the antenna design.

Theory and Design of Dual-Band Microstrip Networks Using Embedded Metamaterial-Based Electromagnetic Bandgap Structures

This article examines implementations of the recently introduced metamaterial-based electromagnetic bandgap (MTM-EBG) structure, which may be embedded directly into the transmission-line (TL) segments of microstrip (MS) networks and whose dispersion properties may be accurately determined using multiconductor TL (MTL) theory. Two methods of imparting dual-band behavior to MS-based networks are introduced: utilizing stopband and passband regions of the EBG for frequency-selective signal routing, and using the phasing properties of the EBG to provide equal phase shifts at two separate frequencies. Two topological variants of the MTM-EBG are introduced and shown to provide different bandgap sizes, suiting each proposed application. A dual-band Wilkinson power divider, a dual-band quadrature hybrid coupler, and a dual-band impedance transformer are designed with embedded MTM-EBGs, which due to their ability to be realized in an entirely uniplanar form without vias and using a single dielectric layer, allow these devices to be entirely printable as well. The performance characteristics of all three devices are simulated and demonstrate excellent agreement with measurements. The design methodology is general and based on a rigorous MTL circuit model, making this approach amenable to a variety of MS networks, beyond what is presented.

Dual band low loss metamaterial structure at millimetre wave band

In this paper, the Dual band modified split square resonator (MSSR) metamaterial (MM) structure was designed and numerically investigated at millimetre wave (mm-Wave) frequency range. The proposed structure operated at two resonance frequencies 28 GHz and 32.54 GHz. The dual-band behaviour of the proposed structure because of the self and mutual coupling between two metallic squares of the structure. Furthermore, The MSRR structure performed very well at both resonance frequencies by providing high transmission coefficient, S21, with a loss of -0.3 dB (0.97 linear scale) at lower resonance frequency 28 GHz and -0.18 dB (0.98 linear scale) at upper resonance frequency 32.54 GHz. In this regard, the numerical simulation was conducted to optimize the MSSR structure in such a way that the ratio of effective inductance-to-capacitance (L/C) was raised. As a result, the inherent MM losses were reduced. The robust retrieval algorithm was utilized to reconstruct the refractive index, effective permittivity, and effective permeability and to verify the left-hand property of the proposed structure. The simulation results showed that the MSSR unit cell introduces two regions of the negative refractive index below the lower resonance frequency, 28 GHz and above the upper resonance frequency, 32.54 GHz.

Optimization of Efficient Dual Band PIFA System for MIMO Half-Duplex 4G/LTE and Full-Duplex 5G Communications

In this paper, a two efficient Planar Inverted-F Antenna (PIFA) system for dual-band functionality on fourth-generation (4G) band (2.5-2.7 GHz) and future fifth-generation (5G) band (3.4-3.8 GHz) is presented. During the optimization process, in order to obtain an efficient system, particular attention has been paid to the antenna system efficiency as well as the isolation between the antennas. Thus, the influence of the antenna slot design used to achieve a dual-band behavior on the antenna efficiency has been particularly studied. Moreover, the antenna positions on the Printed Circuit Board (PCB) have been chosen thanks to the use of characteristic mode analysis to obtain high isolation levels in both bands. The final system is optimized for Multiple Input Multiple Output Half Duplex (MIMO HD) 4G communications and Tx/Rx Full-Duplex (FD) 5G communications. A prototype with 140 mm × 70 mm ground plane was simulated, fabricated and measured. A high isolation level between the two ports of the PIFA elements, better than 35 dB in 5G band and 20 dB in 4G band in simulation and measurement that were done in free space, is obtained. Additionally, the most important diversity metrics are computed to evaluate the potential of this two-antenna system for diversity applications.

Multi band multi polarized reconfigurable circularly polarized monopole antenna with simple biasing network

Design of a reconfigurable multiband multi polarized monopole antenna with simple bias circuit is presented. The proposed antenna consists of simple radiating truncated rectangular patch with a cross-shaped slit and a ground plane embedded with L-shaped slit. The antenna produces two separate impedance bandwidth with three senses of polarization namely right hand circular polarization, left hand circular polarization and linear polarization. PIN diode is used to reconfigure the L-shape slit in the ground plane. The antenna generates dual band behavior with multiple circularly and linearly polarized bands. With OFF state of the diode, the impedance bandwidth of the antenna is 10.22% and 83.43% from 3.99 GHz to 4.42 GHz and 5.84 GHz to 14.20 GHz, respectively, while 3-dB axial ratio bandwidths are 9.83% and 13.73% from 5.79 GHz to 6.39 GHz and 8.49 GHz to 9.74 GHz, respectively. In the ON state, antenna also shows the dual band behavior with an impedance bandwidth of 49.10% and 21.31% from 7.20 GHz to 11.04 GHz and 12.66 GHz to 15.37 GHz, respectively, while 3-dB axial ratio bandwidth of 6.49%, 8.45% and 2.0% from 7.90 GHz to 8.43 GHz, 10.08 GHz to 10.97 GHz and 12.87 GHz to 13.13 GHz, respectively.

Novel dual band patch antenna With Gap coupled composite right/left-handed transmission line

AbstractA novel low profile dual band patch antenna is presented. It consists of a composite right/left-handed transmission line (CRLH TL) unit cell gap coupled with the radiating edge of a rectangular patch antenna. The dual band behavior is achieved by coupling the zeroth order resonance mode of CRLH TL and TM10 mode of the patch antenna. It is shown that frequency ratio can be changed by varying the gap between the patch and CRLH TL unit cell. The proposed configuration enables frequency reconfigurability by changing the CRLH TL unit cell using a switch. A prototype of the antenna having frequency ratio f2/f1 = 1.08 is designed and fabricated. The proposed antenna shows measured S11 ≤ −10 dB bandwidth of 100 and 50 MHz at resonance frequencies of f1 = 4.84 and f2 = 5.22 GHz, respectively. A 2 × 2 dual band CRLH TL coupled patch array is also presented, showing more than 12.7 dBi gain at both resonance frequencies.

Dual band microstrip patch antenna array loaded with split ring resonators and via holes

Reduction in antenna size by using multi-band radiators play a vital role in the miniaturization of present world wireless handheld devices, as dual band behaviour of the antennas result in the integration of more than one communication standard in a single system and thus, saving the installation space required for separate antennas. In this context, this communication presents a shorted-pin dual band metamaterial inspired microstrip patch antenna array. Under the unloaded conditions, the traditional patch antenna array resonates at 5.8 GHz with gain of 9.8 dBi and bandwidth of 540 MHz. However, when each patch of this traditional antenna array is loaded with split ring resonator (SRR) and a metallic via hole is introduced in the patch, the same antenna array produces an additional resonant frequency in IEEE 802.11b/g/n 2.45 GHz Wi-Fi band with bandwidth and gain of 290 MHz and 5.6 dBi, respectively, while the initial resonant frequency (i.e. 5.8 GHz) gets shifted to IEEE 802.11ac 5 GHz Wi-Fi band, providing the gain and bandwidth of 11.4 dBi and 510 MHz, respectively. The proposed antenna array has been fabricated, and the measured results are presented to validate the proposed array. Moreover, the equivalent circuit of the proposed antenna array has been designed and analyzed to validate the simulated, measured and theoretical results. Attainment of dual band characteristics by incorporating the metamaterial with single band traditional patch antenna array makes this structure novel, as this has been achieved without any extra hardware cost, size and loss of structural planarity. Also, both the frequency bands of this proposed metamaterial inspired antenna array possess considerable gain and bandwidth.

Wideband or Dual-Band Low-Profile Circular Patch Antenna With High-Gain and Sidelobe Suppression

This communication presents a wideband or dual-band circular disk antenna with high-gain and sidelobe suppression (SLS). The antenna has a single layer and single-fed configuration. The antenna can operate with the radiation field superposition of TM12 and TM14 modes at one frequency, which provides high-gain and SLS. A circle of 10 shorting vias with nonidentical diameters are loaded inside the antenna cavity in order to excite the field superposition of TM11 and TM13 modes at another frequency. By modifying the radius of the vias, the resonant frequency with the TM11 and TM13 superposition can be tuned closer to or further away from the one with the TM12 and TM14 superposition. In this way, a wideband or dual-band behavior can be obtained with high-gain and SLS. The proposed antenna achieves the impedance bandwidth of 6.46% for the wideband case, which is over 6 times wider than the previous literature. In the dual-band case, the bandwidth is 1.48% and 1.61% at each band. For both cases, the gain and the SLS are higher than 15 dBi and 10 dB within the operating bands, respectively. Measurements are carried out with prototypes and agree well with simulations.

Novel Dual-band Band-Pass Filters Based on Surface Plasmon Polariton-like Propagation Induced by Structural Dispersion of Substrate Integrated Waveguide

In this paper, we present two novel dual-band bandpass filters based on surface plasmon polariton-like (SPP-like) propagation induced by structural dispersion of substrate integrated waveguide (SIW). Both filters are realized as a three-layer SIW where each layer represents a sub-SIW structure with intrinsic effective permittivity that depends on its width and filling dielectric material. The layers are designed to have effective permittivities of opposite signs in certain frequency ranges, which enables SPP-like propagation to occur at their interfaces. Since three layers can provide two distinct SPP-like propagations, the filters exhibit dual-band behaviour. A detailed theoretical and numerical analysis and numerical optimization have been used to design the filters, which were afterwards fabricated using standard printed circuit board technology. The independent choice of geometrical parameters of sub-SIWs and/or the corresponding dielectric materials provide a great freedom to arbitrarily position the passbands in the spectrum, which is a significant advantage of the proposed filters. At the same time, they meet the requirements for low-cost low-profile configuration since they are realized as SIW structures, as well as for excellent in-band characteristics and selectivity which is confirmed by the measurement results.

Reconfigurable and stable frequency selective surfaces on nonuniform and finite arrays

AbstractA reconfigurable frequency selective surface (FSS) is presented based on a nonuniform and finite array of square loop conducting patches printed on a dielectric substrate. The reconfigurability is performed changing the polarization of PIN diodes in the patch elements of the FSS array, from OFF to ON state and vice versa. Simulation is performed by the wave concept iterative procedure (WCIP) formulation and Ansoft HFSS package. Remarkably, a generalization of the WCIP method is proposed to solve scattering problems on FSS structures composed of nonuniform and finite arrays. Prototypes are fabricated for comparison purpose. Simulations and measurements show that the nonuniform and finite FSS has dual band behavior and stable frequency response for different angles of the incident plane wave. A very good agreement between HFSS simulation, WCIP formulation, and experimental results is verified.