Tri-band Operation Research Articles

Design and measurement of a thirty-two-port MIMO/diversity antenna based on radiator-ground isomorphic inverse approach for intelligent vehicular internet of things communications

The increased demand for automobile applications and connected-vehicles in the market has prompted much research into intelligent automotive antennas. Connected-vehicles are being used to change automotive technology and serve as a framework for a smart society. This paper presents a thirty-two-port hex‑polarized massive multiple-input-multiple-output (MIMO) antenna that operates at GPS, Wi-Fi, and ultra-wideband (UWB) frequencies. In the proposed MIMO antenna, thirty-two-unit cells are populated in 3D configuration, where eight-unit cells are arranged in the horizontal plane and twenty-four-unit cells are arranged in four different vertical planes. The unit cell, based on an isomorphic inverse approach, consists of a semi-circular radiator with integrated meandered slots and achieves a tri-band operation at 1.5 GHz, 2.4 GHz, and 3.1 to 11 GHz. The unit cell has a size of 20 mm × 20 mm and the developed MIMO architecture has dimensions of 85 mm × 85 mm. The peak gain of the proposed antenna is 3.85 dBi, and the efficiency is 89.5%. The MIMO antenna assembly exhibits a calculated Envelope Correlation Coefficient (ECC) using far-field, less than 0.1. The Total Active Reflection Coefficient (TARC) is found to be less than -10 dB and the difference of Mean Effective gain (MEG) is less than 1 dB. Also, Apparent Diversity Gain (ADG) and Effective Diversity Gain (EDG) by far-field method are found to be above 9 dB. Antenna assemblies like the one proposed, are filled in various layouts on 3D vehicular space to combat the diversity reception issues, catering to spatial and polarization needs. In order to substantially validate the designed MIMO antenna for vehicular applications, housing effects and on-car analysis have been studied.

Polarization-Insensitive Triband FSS for RF Shielding at Normal and Higher Temperatures by Retrofitting on Ordinary Glass Windows

A comprehensive novel framework for retrofitting frequency-selective surface (FSS) shields to any glass surface using low-cost copper foils has been proposed in this work. The realization technique is demonstrated through a novel triband FSS shield. Global System for Mobile Communication (GSM)-1800, Wi-Fi 2.5 GHz, and wireless local area network (WLAN) 5.6 GHz spectrum, with–10 dB bandwidth of 680, 190, and 1300 MHz, respectively, are suppressed by the shield. The unit cell is made up of a combination of square and circular concentric loops with some alterations. The design is entirely polarization-insensitive and has a steady frequency response for oblique angles up to 60°. The unit element is highly miniaturized for triband operation measuring <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\lambda _{0}$ </tex-math></inline-formula> /9 at 1.8 GHz frequency. An equivalent circuit model (ECM) is also derived to better elaborate the working mechanism of the shield. The pattern is chemically etched on low-cost copper adhesive foil and affixed to ordinary glass as a sticker. The design retains the visual transparency of 72% allowing enough light to enter through windows while rejecting the intended frequencies by at least 28 dB or more in all three bands. The design exhibits a very high shielding efficiency of above 98% for all three bands. Experimental demonstration for single-layer glass, sandwiched glass, as well as air-filled double-glazed glass is carried out. The thermal stability of the proposed design is measured and found intact up to the ambient temperature of 50 °C.

A THREE-BAND PATCH ANTENNA USING A DEFECTED GROUND STRUCTURE OPTIMIZED BY A GENETIC ALGORITHM FOR THE MODERN WIRELESS MOBILE APPLICATIONS

This paper presents a design and optimization approach for a tri-band miniature planar rectangular patch antenna structure for wireless mobile applications. The tri-band operation while maintaining a compact size has been achieved by introducing a defected ground structure (DGS) to control the surface current distribution on the patch antenna and consequently achieve multi-band operation. The geometry of the patch and the position of the DGS were optimized by a genetic algorithm to achieve the desired performance using a simple and miniature design with an area of 16 mm × 20 mm × 1.6 mm, an 82% reduction in the area occupied by a conventional single-band structure used in the optimization process. The proposed GA-optimised antenna provided tri-band operation with bandwidths for |?11| &gt; 6 from 3.2 - 3.5 GHz, 5.5 - 5.9 GHz and 6.3 - 7.1 GHz. At the centre frequencies of 3.4, 5.7 and 6.7 GHz, the peak gains were 0.7, 1.76 and 2.93 dB, respectively. The optimally designed antenna is etched on an FR-4 substrate. Simulation and measurement results show good agreement, making the proposed structure a suitable candidate for mobile applications requiring small and multifunctional telecommunication devices.

Compact Tri-Band Antenna with Double Winding Structures for 3G/4G/5G Base Station Applications

This paper presents a compact tri-band antenna with double winding structures for 3G/4G/5G base station applications. The proposed compact tri-band antenna design with double winding structure fed by a coplanar waveguide (CPW) reduces the installation space and mutual coupling between close frequency operation bands suitable for base band applications. The proposed antenna design can be configured for step-up and step-down transformer operation using double winding structures on either side of the central resonator with an ability to attain reversibility of transformer operation. The proposed compact tri-band antenna performance is evaluated for both with and without windings in the antenna structure. The proposed design without the winding structure achieves a dual band of operation whereas the design with a winding structure achieves tri-band operation with improved S11 performance and very less voltage standing wave ratio (VSWR). Two prototypes of tri-band ultra-wideband (UWB) antenna with double winding structures of high design specifications are fabricated and tested to validate the proposed design principle. The effectiveness of the projected design is evident from the excellent association between simulated and measured results. It is shown that the proposed design is very effective with low cost and the fabricated prototypes of the antenna with double winding structures are very compact with the dimensions of 18.6 X 15.6 mm2 achieving three frequency bands of operations at 2.9 GHz, 6.5 GHz, and 11.3 GHz with improved return loss < -10db and VSWR < 1.8.

A Wearable Tri-Band Half-Mode Substrate Integrated Waveguide Antenna

A wearable tri-band half-mode substrate integrated waveguide (HMSIW) antenna is proposed for wireless body area network (WBAN) applications. The lower frequency band is generated by combining the TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">010</sub> and TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">110</sub> modes of the HMSIW cavity, whereas the middle and upper bands are achieved with the stubs and the slot. Simulated and measured results show that the antenna can cover the three frequency bands, i.e., 2.36–2.5, 3.32–3.54, and 5.61–6.12 GHz with broadside radiation patterns. The antenna performance is evaluated on the human tissue model. Owing to the isolation characteristic of the cavity structure, the performance of the antenna on the body will not degenerate significantly compared to the results in free space. Due to the advantages of tri-band operation, simple topology, low back radiation, and low specific absorption ratio values, the proposed antenna is a competitive candidate for WBAN applications.

Low-Profile Dual Hollow Octagonal Ring Shaped Optically Transparent Tri-band Antenna for WLAN and Sub-6 GHz 5G Applications

A transparent dual octagonal split ring-shaped resonator connected by a horizontal strip is proposed for tri-band applications. Stub-loaded microstrip line fed structural design of radiator consists of two slotted octagonal-shaped rings connected via a strip on the top with the partial ground at the back. The low profile (40×25 mm2) radiator achieves impedance bandwidth of (46.08%) 1.62-2.59,(7.78%) 3.95-4.27, and (12.60%) 5.13-5.82, respectively. A bi-directional (dipole shaped) radiation pattern with maximum gain and minimum efficiency of 2.5 dBi and 52%, respectively is achieved. Transparency above 80%, low profile structure, and tri-band operation make the antenna a good contender for WLAN and Sub-6 GHz 5G applications. Good correlation is observed for the modeled and experimental parameters. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium provided the original work is properly cited.

A Multistandard Antenna Based on a 2-D CRLH-TL in Polar Coordinates

A novel 2-D composite right/left-handed transmission line (CRLH-TL) metamaterial in polar coordinates is proposed for the first time, and applied to a multistandard antenna. The prototype antenna with triband operation and colocated pattern and polarization diversity is specifically designed to eliminate the need for multiple antennas in the processing center side and to significantly reduce antenna area and cost. Radial CRLH-TL waves of mode type 0 and 1 are simultaneously excited by port 1, working in the 2.5 GHz Industrial, Scientific, and Medical (ISM) band and the 3.3 GHz WiMAX band, respectively. Annular CRLH-TL waves of mode type −1 and +1 are simultaneously excited by port 2, covering the 915 MHz RFID band, and the 2.5 GHz ISM band, respectively. The 0 and 1 modes in the r -direction result in omnidirectional patterns due to the circular symmetry. The −1 mode and +1 mode in the ϕ -direction result in directional patterns, thanks to the aperture-coupled feeding topology.

Design of Reconfigurable Tri-Band Antenna for Wireless Communication

The Design is a quotidian rectangular patch antenna which functions on three Different frequency bands. Tri-band antenna is an electronic device that can operate in three different frequency bands. Taking the advantage of antenna parameter modification in to account the tri-band operation is achieved. Reconfigurable antenna is capable of modifying its frequency and radiation properties in a controlled and changeable manner. The antenna is designed with the use of dielectric substrate of 1.6mm thickness with permittivity of 4.6. The design is simulated in HFSS platform. In designed antenna, configuration I engages in three different bands of frequencies 1.3 ∼ 3, 4.1 ∼ 4.7, 6.1 ∼7.6 GHz where the return loss value is around and below -10 dB. The Configuration I is designed to have an enhanced performance over a specified range of frequency (1.5 GHz to 3 GHz). But configuration II is devised to have a subsided performance over all UWB frequency ranges. The return loss of configuration II is -15 dB over 1.25 GHz to 2 GHz range and -12 dB over 4.25 GHz to 5.75 GHz range, -14 dB for 7.5 GHz to 8.5 GHz range. Switching between the frequencies is achieved using three symmetrical ideal RF MEMS switches. The Patch antenna which can be applicable to wireless communication systems like Sensing, RFID, WLAN is presented.

Design of tri-band chiral graphene based terahertz patch antenna

In this paper, a novel terahertz patch antenna is designed using a very thin layer of graphene as the radiating patch, to get tri-band operation. An attempt, is made to design both achiral and chiral graphene patch tri-band for 0.46/0.58/0.66-THz. The simulation has been carried out by using a full wave electromagnetic simulator based on FDTD method. We then expect these results to be of interest to scientists in the field of the interaction between the electromagnetic wave and grapheme to design potential application.

Design of a miniaturized tri-band bandstop filter using spur microstrip lines and via-hole grounding

PurposeThe purpose of this paper is to propose a miniaturized tri-band bandstop filter that finds application in a modern dense communication system where size and multi-band plays a vital role.Design/methodology/approachIn this paper, the authors propose a miniaturized tri-band microstrip bandstop filter which combines the conventional bandstop filter and spur microstrip line structures such that this design achieves tri-band operation at 1.8 GHz and 3 GHz. The overall length of the microstrip filter is found to reduce from 126 to 45 mm because of introduction of spur lines and via-hole grounding. The addition of spur lines replaces two resonators, introduces two additional resonant frequencies and enhances the −6 dB bandwidth of the center frequency by 14 %.The addition of via-holes in each resonator reduces its length into half of its original length, thereby reducing filter size.FindingsResonance occurs at three different frequencies 1.8, 2.4 and 3 GHz. The filter size reduces from 126 to 45 mm, and the −6 dB rejection bandwidth of center frequency improves by 14 %.Originality/valueThe overall filter size is reduced by 65% and it resonates at three different frequencies 1.8, 2.4 and 3 GHz with an improved bandwidth of 10 % around the center frequency.

Design and performance analysis of tri-band Wang shaped MIMO antenna

This paper presents the design of a compact Wang shape MIMO antenna with tri-band operation for LTE 2500, 2.4/5.2 GHz WLAN, 2.5 GHz WiMAX, 8 GHz ITU application. The Wang shape MIMO antenna occupies an overall size of 70 × 52 mm2 that includes the ground plane and substrate. The radiating elements are used to generate three resonant frequencies at 3.1 GHz, 6.2 GHz and 7.7 GHz. The simulated impedances bandwidths (|S11| < − 10 dB) are about 110 MHz (3.1–3.2101 GHz), 90 MHz (6.2–6.3386 GHz) and 280 MHz (7.6–7.9029 GHz) for three operating bands respectively. Here the return loss and mutual coupling of the proposed antenna system are improved over the three resonant frequencies. The simulated result shows reasonably good agreement with the measured results by using R&S ZVA 40 vector network analyzer. The radiator has a low envelope correlation coefficient with values are equal to approximately less than 0.025, which will proves that the wang-shape MIMO radiator shows better diversity performance. The wang-shape MIMO radiator has improves the parameters of reflection coefficient, mutual coupling, realized gain, group delay, real/imaginary impedances and diversity gain.

A Tri-Band Full-Duplex Cognitive Radio Transceiver for Tactical Communications

RF spectrum represents a limited natural resource. The increasing numbers of wireless devices demand more and more spectrum for diverse future applications and services. CR is explored as a technological solution to the current paradigm of spectrum scarcity by opportunistically sharing the spectrum with licensed users. FD operation further enhances the performance of CR with higher throughput and optimized sensing time. Tactical radios are traditionally operated in the licensed frequency bands. To comply with the soaring demands, alternative means are explored to share the spectrum among tactical users. In this article, an FD-CR integrated with tri-band operation and dynamic spectrum shaping is proposed for tactical communications. The proposed radio is implemented in the Zynq SDR platform. The performance results reveal that the FD-CR offers higher throughput, higher probability of detection (Pd > 0.9), and optimized sensing time, which empowers the system to be ideally suitable for tactical communication networks.

Triband Operation Enhancement Based on Multimode Analytics of Modified Rhombic Ring Structure with Fractal Ring Parasitic

This paper presents a triband operation enhancement based on multimode analytics of a monopole antenna designed by combining a rhombic ring radiator with a strip on a top layer and a fractal ring resonator placed at the bottom layer. The proposed antenna can achieve triband operation to support the modern wireless communication systems. The antenna size is approximately 36 × 52 mm2, which is quite compacted compared with the revised antenna. The simulation and measurement results are in good agreement. The antenna covers the operating bands at 22.22%, 9.8%, and 31.27% at the resonant frequencies of 1.8 GHz, 2.45 GHz, and 3.71 GHz, respectively, to support the application bands of LTE 1800, WLAN IEEE802.11b/g, WiMAX, and IMT Advanced Systems (5G). The average gain of the antenna is about 2 dBi. Also, the radiation patterns are omnidirectional for all operating frequencies.

Multiport Network Model of Double–stub Loaded Microstrip Ring Antenna for Tri–band Operation

Multiport Network Model of Double–stub Loaded Microstrip Ring Antenna for Tri–band Operation

A Compact Tri-Band Impedance-Transforming Power Divider With Independent Controllable Power Division Ratios and Enhanced Bandwidths

In this paper, a tri-band impedance transformer (TBIT) using a coupled line and a dual-band to tri-band transformer is proposed, which can transform frequency-dependent complex impedances to a real-value impedance. In order to explain how to determine circuit parameters, closed-form equations are derived in detail. Based on the TBIT, a compact T-junction power divider (TTPD) is designed. This TTPD works at three different frequencies with independent controllable power division ratios. Simple steps to design the TTPD are listed. To demonstrate the validity of the theory, this paper exhibits a prototype operating at 2, 4.4, and 5 GHz with different power division ratios. Moreover, the simulated and measured results prove that this TTPD has the features of tri-band operation, independent controllable power division ratios, enhanced bandwidths, and small size.

Folded monopole antenna with CSRRS for tri-band applications

In this paper, a miniaturize folded monopole antenna with complementary split ring resonator (CSRR) is proposed for tri-band applications. In the design procedure of the antenna, first a single band monopole antenna is designed for 2.88 GHz. For design a single band to dual band, the both arms of the radiating element (i.e. Monopole) is folded then it is resonated at 2.68GHz and 5.15GHz resonance frequencies, the resonance of the lower frequency is based on length of the monopole and higher order resonance is excited due to its folding effect. In order to extend its resonances for tri-band operation, the two identical size CSRRs (one on the left and another on the right from the feed line) are placed on the ground plane of the edge of the folded monopole, thus the entire structure is resonated at 2.47 GHz, 3.46GHz and 4.36 GHz frequencies. A simplified equivalent circuit model is developed for understanding its electrical behavior. Therefore, the proposed antenna has been suitable for WLAN, WiMAX and C-band applica- tions.

4-Element Concentric Pentagonal Slot-Line-Based Ultra-Wide Tuning Frequency Reconfigurable MIMO Antenna System

In this communication, a novel, compact, ultrawideband tuning, concentric pentagonal slot-line-based frequency-reconfigurable multiple-input-multiple-output (MIMO) antenna system is presented. It consists of a four-element antenna design on a commercially available FR-4 substrate with the dimensions of $60\times 120\times 1.56$ mm3. All the antenna elements are planar in structure, which are etched out from ground plane. Frequency reconfigurability is achieved using varactor diodes by reactively loading the antennas. Each capacitance value of the varactor diode results in the triband operation. Proper capacitive reactance loading enables the antenna to resonate over a wide frequency band. The proposed MIMO antenna system is tuned over an ultrawide frequency band, and a smooth variation of the resonance frequencies is observed from 1.32 to 1.49 and 1.75 to 5.2 GHz. Moreover, the unique feature of the proposed antenna system is the effectiveness of reactively loading the slot over all the resonating bands. The proposed antenna system is compact and suitable to be used in wireless handheld devices and mobile terminals for cognitive radio applications. The envelope correlation coefficient did not exceed 0.186 in the entire operating band of the MIMO antenna operation. The maximum measured gain of the MIMO antenna is 4.5 dBi with a maximum efficiency of 81%.

New Dual-/Tri-Band Bandpass Filters and Diplexer With Large Frequency Ratio

To satisfy the simultaneous requirements of future wireless communication systems on short-range high-speed data transmission and long-distance basic coverage, the coexistence of the millimeter-wave and microwave technologies becomes the inexorable trend. However, it is difficult for the existing dual-/ tri-band filter configurations to achieve a frequency ratio larger than three. In this paper, the new use of aperture coupling mechanism is proposed to combine two bandpass elements for dual-/tri-band operation with large frequency ratio but comparable sizes. For this purpose, a microwave BPF with wide stopband up to millimeter-waveband is implemented based on the complementary frequency response characteristics of the stepped-impedance resonator bandpass filter and low-pass filter. The millimeter-wave BPF can be simply designed using the air-filled substrate-integrated waveguide circular cavities, which exhibit the natural low-frequency cutoff characteristics. Based on the proposed design concept and two BPF elements, the dual-/ tri-band bandpass filters with frequency ratio up to 12.59 and 12.7 were designed, fabricated, and measured. Owing to the independence of the two elements, a diplexer with large frequency ratio can be simply implemented based on the previous dual-band filter. All the simulation and measured results are in good agreement, validating the proposed structures.

Four port MIMO integrated antenna system with DRA for cognitive radio platforms

An integrated four-port multi input multi output (MIMO) system with Cylindrical Dielectric Resonator Antenna (CDRA) for Cognitive Radio (CR) application is investigated. In this study the proposed design performs dual state operation i.e ultrawideband (UWB) and narrowband (NB) functionality with modified feeding mechanism, where the feeding line of UWB antenna is made orthogonal to NB CDRA. In UWB state the proposed integrated antenna consisting of two port circular radiators, excited by micro-strip transmission line. In NB state two CDRAs are integrated on the UWB radiators where the current density is effectively low. The DRAs are excited by aperture coupled orthogonal T feed micro-strip transmission line to perform the triband operation at targeted bands. The proposed integrated MIMO system occupies a compact total area of 0.18λ02(λ0 is the highest operating wavelength) with isolation less than −15 dB among all ports. The design approach is verified by fabricating the antenna prototype and the performances are experimentally evaluated in terms of S parameter, radiation pattern and gain. Moreover, the MIMO performance metrics in terms of Envelope correlation coefficient (ECC), diversity gain (DG) and mean effective gain (MEG) are also evaluated for satisfactory diversity performance.

Tri-band compact ACS-fed meander-line antenna for wireless communications

In this paper, a compact tri-band asymmetric coplanar strip (ACS)-fed meander-line antenna for wireless communications is proposed. Two inverted-L-shaped resonators are added to a simple meandered radiator for standard tri-band operation. Parametric studies indicate that operating frequencies of the proposed antenna are determined by the dimensions of the two inverted-L-shaped resonators. The measured results show that the proposed antenna can achieve three frequency bands; i.e. 1.48–1.63, 2.25–2.48, and 4.22–6.0 GHz. These bands can successfully cover the global positioning system L1, wireless local area network (WLAN), and HIPERLAN/2 operation bands, respectively. The proposed antenna exhibits good radiation patterns with reasonable gain and high radiation efficiency across the operating bands. In addition, the proposed antenna has compact size and simple feeding scheme, which make it suitable to be integrated within the portable device for wireless communications.