Dual‐band beam scanning filtering antenna using dual‐eighth mode substrate integrated waveguide‐based metamaterial structure

In this article, a dual‐band beam scanning antenna with filtering capability is proposed by using novel dual‐eighth mode substrate integrated waveguide‐based dual‐band metamaterial (DB‐MTM) structure. The novel DB‐MTM structure consists of two interconnected modified eighth mode substrate integrated waveguide (EMSIW) structures, which is designed by etching four interdigital fingers on the upper ground, and has two balanced composite right/left‐handed (CRLH) passbands. Taking advantage of the continuous phase constant changing from negative to positive values within the two CRLH passbands of the DB‐MTM structure, a beam scanning antenna, which is composed of 11 dB‐MTM unit cells, is designed to achieve continuous beam scanning from backward to forward directions within dual operating frequency bands. For verification, the proposed dual‐band antenna is fabricated and measured. According to the measurements, the fabricated antenna can scan its main beam from ?72° to +57° and ?70° to +38° over the two operating frequency bands of 3.40‐4.95 GHz and 5.85‐6.80 GHz, respectively; and exhibits very sharp transitions at the band edges over the two operating frequency bands. Besides, the measured peak gains in the two operating bands are 14.0 dB at 4.5 GHz and 14.5 dB at 6.4 GHz. Moreover, the measurements show good agreement with the simulations, proving the validity of the design method, and further expanding the applications of EMSIW.     

Coplanar waveguide‐fed electrically small dual‐polarized short‐ended zeroth‐order resonating antenna using Ω‐shaped capacitor and single‐split ring resonator for GPS/WiMAX/WLAN/C‐band applications

This work explains the design and analysis of a triple‐band electrically small (ka = 0.56 < 1) zeroth‐order resonating (ZOR) antenna with wideband circular polarization (CP) characteristics. The antenna compactness is obtained due to ZOR frequency of composite right/left‐handed (CRLH) transmission line (TL) and wideband CP radiation are achieved due to the introduction of single‐split ring resonator and asymmetric coplanar waveguide fed ground plane. The proposed antenna obtains an overall electrical size including the ground plane of 0.124 λ₀ × 0.131 λ₀ × 0.005 λ₀ at 1.58 GHz and physical dimension of 23.7 × 25 × 1 mm³ are achieved. The antenna provides a size reduction of 44.95% compared to a conventional monopole antenna. The novelty behind the ohm‐shaped capacitor is the generation of extra miniaturization with better antenna compactness. The antenna provides dual‐polarized radiation pattern with linear polarization radiation at 1.58 and 3.54 GHz, wideband CP radiation at 5.8 GHz. The antenna measured results shows good impedance bandwidth of 5%, 6.21%, and 57.5% for the three bands centered at 1.58, 3.54, and 5.8 GHz with a wider axial ratio bandwidth (ARBW) of 25.47% is obtained in the third band. The antenna provides a higher level of compactness, wider ARBW, good radiation efficiency, and wider S₁₁ bandwidth. Hence, the proposed antenna is suitable for use in GPS L1 band (1.565‐1.585 GHz), WiMAX 3.5 GHz (3.4‐3.8 GHz) GHz, WLAN 5.2/5.8 GHz (5.15‐5.825 GHz), and C‐band (4‐8 GHz) wireless application systems.     

CPW fed miniaturized dual‐band short‐ended metamaterial antenna using modified split‐ring resonator for wireless application

A miniaturized dual‐band metamaterial (MTM) antenna has been designed in this article. The designed coplanar waveguide fed antenna has composed of inner split‐ring resonator and an outer open ring resonator with rectangular stub. The series parameter of the antenna is used to determine the zeroth order resonance frequency due to short‐ended boundary condition. The whole size of proposed structure is 20 × 25.5 mm². This MTM antenna exhibits dual‐band operation at 3.17 GHz (3.1–3.22 GHz) and 5.39 GHz (5.27–5.47 GHz). The proposed MTM structure achieves measured peak gain of 0.71 and 1.89 dB at 3.17 and 5.39 GHz, respectively. The proposed antenna can be used for recent radio communication in form of S‐band application and Wi‐MAX.     

A metamaterial hepta‐band antenna for wireless applications with specific absorption rate reduction

Present article embodies the design and analysis of slotted circular shape metamaterial loaded multiband antenna for wireless applications with declination of SAR. The electrical dimension is 0.260 λ × 0.253 λ × 0.0059 λ (35 × 34 × 0.8 mm³) of proposed design, at lower frequency of 2.23 GHz. The antenna consists of circular shape rectangular slot as the radiation element loaded with metamaterial split ring resonator (SRR) and two parallel rectangular stubs, etched rectangular single complementary split‐ring resonator (CSRR) and reclined T‐shaped slot as ground plane. Antenna achieves hepta bands for wireless standards WLAN (2.4/5.0/5.8 GHz), WiMAX (3.5 GHz), radio frequency identification (RFID) services (3.0 GHz), Upper X band (11.8 GHz—for space communication) and Lower K_U band (13.1 GHz—for satellite communication systems operating band). Stable radiation patterns are observed for the operating bands with low cross polarization. The SRR is responsible for creating an additional resonating mode for wireless application as well as provide the declination in SAR about 13.3%. Experimental characteristic of antenna shows close agreement with those obtained by simulation of the proposed antenna.     

A hexa‐band dual‐sense circularly polarized antenna for WLAN/Wi‐MAX/SDARS and C‐band applications

In this article, a compact single fed hexa‐band circularly polarized (CP) monopole antenna using split ring resonators (SRRs) on the partial ground plane is designed and experimentally investigated. The loaded SRR elements generate multiple circularly polarized bands along with a reduction in antenna size. The multiband can be controlled by changing the configuration of SRRs and their position on the ground plane without altering the monopole radiator. To illustrate the CP mechanism and multiband operation of the proposed configuration, the surface current density has been studied. The antenna is fabricated on RT Duroid 5880 substrate of permittivity 2.2 with a total size of 47 × 40 × 1.57 mm³. Compared with the existing antenna designs, the proposed structure is compact and demonstrates improved multiband performance with circular polarization.     

A miniaturized multi‐wideband Quasi‐Yagi MIMO antenna system

A multi‐band directional multiple‐input–multiple‐output (MIMO) antenna system is presented based on a rectangular loop excited Quasi‐Yagi configuration. A 64% reduction in size is obtained using a rectangular meandered element as well as a small ground plane. The proposed two‐element MIMO antenna system covers the Telemetry L‐band and several LTE/WLAN bands. It has a wide measured bandwidth of 689 MHz (1.897–2.586 GHz) in the desired band centered at 2 GHz, and a measured bandwidth of more than 168 MHz across rest of the bands. The MIMO antenna system has a total size of 45 × 120 × 0.76 mm³, with a single element size of 55 × 60 × 0.76 mm³. The non‐desired back‐lobe radiation which is obtained using a small ground plane, is significantly reduced by using a novel defected ground structure (DGS) as compared with the complex techniques present in literature. The proposed DGS provides a high measured front‐to‐back ratio of 14 dB at 2 GHz and 11 dB in other bands. A maximum measured realized gain of 5.8 dBi is obtained in the desired band using a single parasitic director element. The proposed MIMO antenna system has a minimum measured radiation efficiency of 70%, isolation of 12 dB, and envelope correlation coefficient of 0.098 within all bands which ensures very good MIMO performance.     

A dual‐band antenna design for MIMO LTE applications with reduced ground effects

A dual‐band planar long term evolution (LTE) antenna design is initially proposed. The size of this proposed antenna is 40 mm × 15 mm × 0.8 mm, and its structure is meticulously designed to achieve reduce ground effects, so that the ground plane size can be altered without affecting the antenna's performance. The 6‐dB impedance bandwidths of both lower and upper operating bands of proposed antenna are 13.1% (695–790 MHz) and 37.6% (2200–3120 MHz), respectively. Minimum radiation efficiencies of up to 56% are also exhibited within the three LTE bands (LTE 700/2300/2600 MHz). This proposed antenna is later used as a two‐antenna multiple input multiple output (MIMO) system for laptop computer application, and because of its reduced ground effects, good envelope correlation coefficient (ECC) of less than 0.14 and 0.0022 are measured across the lower and upper operating bands, respectively. © 2015 Wiley Periodicals, Inc. Int J RF and Microwave CAE 26:80–87, 2016.     

Dual‐band dual‐polarized compact planar monopole antenna for wide axial ratio bandwidth application

In this article, a geometrically simple, microstrip line‐fed planar monopole structure with slanting edge ground plane is designed to realize the dual‐band dual‐polarized operation. The proposed antenna consists of a rotated U‐shaped patch and an electromagnetically coupled L‐shaped parasitic radiating element. Owing to the combination of microstrip line‐fed radiating patch and a slanting‐edge rectangular ground plane on the opposite side of the substrate, the proposed dual‐band antenna can generate broad axial ratio bandwidth (ARBW) in the upper frequency band. The overall dimension of the prototype is only 32 × 32 × 1.6 mm³. The measured results validate that the proposed antenna has two operational frequency bands, 29.84% (1.54‐2.08 GHz) for linearly polarized radiation and 71.85% (3.96‐8.4 GHz) for circularly polarized radiation. Measured result shows that 3‐dB ARBW of the proposed antenna is 73.54% (3.80‐8.22 GHz) in the higher frequency band. It shows that the higher frequency band exhibits a left‐hand circularly polarized radiation in the boresight direction.     

Miniaturized dual‐band metamaterial inspired antenna with modified SRR loading

A miniaturized dual‐band CPW‐fed Metamaterial antenna with modified split ring resonator (SRR) loading has been presented in this paper. Proposed antenna comprises a tapered rectangular patch with a slot in which an elliptically SRR has been loaded to achieve miniaturization. Proposed antenna shows dual band operations in the operating band 3.25‐3.42 and 3.83‐6.63 GHz, respectively. It has been observed that lower mode (at 3.36 GHz) is originated by means of modified SRR. SRR is being modified by small meandered line inductor which is placed instead of strip. This provides an extra inductance to SRR resulting miniaturization. Overall electrical size of the proposed antenna is 0.222 × 0.277 × 0.017 λ₀ at 3.36 GHz. Second band is due to coupling between feed and ground planes. The antenna offers an average peak gain of 1.72 and 3.41 dB throughout the first and second band respectively. In addition to that this antenna exhibits perfect omnidirectional and dipolar radiation patterns at xz‐ and yz‐ plane respectively. Due to consistent radiation pattern, ease of fabrication, and compact nature this antenna can be used for wireless applications such as worldwide interoperability for microwave access (WiMAX), industrial, scientific and medical (ISM) band, WLAN/Wi‐Fi bands.     

A modified fractal‐shaped slotted patch antenna with defected ground using metasurface for dual band applications

A novel modified fractal‐shaped slotted patch antenna employing metasurface at bottom plane along with partial ground has been proposed in this work for dual band applications with significant gain. A 4 × 5 order metasurface has been formed in the ground plane by introducing a periodic combination of two L‐type patches with centered C‐type shaped patch. The top conductor and the ground plane are designed on a 1.6 mm thick FR4 dielectric with the dimension of 28 × 28 mm². The antenna is designed in such a way that it operates over the dual frequency ranges viz., 1.80 to 5.70 GHz and 10.38 to 10.94 GHz. The maximum return loss of 21 dB has been achieved over 2.60 GHz while the maximum realized gain of 7.16 dBi has been obtained at 10.92 GHz. The designed antenna offers omnidirectional radiation characteristics in the first band while directional radiation characteristics have been observed in the second band. The proposed antenna can be utilized for WiMAX 3.5/5.5 GHz, mobile, radio astronomy, and microimaging in medical analysis.     

A vertex‐fed hexa‐band frequency reconfigurable antenna for wireless applications

Present article embodies the design and analysis of an octagonal shaped split ring resonator based multiband antenna fed at vertex for wireless applications with frequency‐band reconfigurable characteristics. The proposed antenna is printed on FR4 substrate with electrical dimension of 0.4884 λ × 0.4329 λ × 0.0178 λ (44 × 39 × 1.6 mm³), at lower frequency of 3.33 GHz. The antenna consists of SRR based vertex fed octagonal ring as the radiation element and switchable reclined L‐shaped slotted ground plane. Antenna achieves six bands for wireless standards viz: upper WLAN (5.0/5.8 GHz), lower WiMAX (3.3 GHz), super extended C‐band (6.6 GHz), middle X band (9.9 GHz—for space communication), and lower K_U band (15.9 GHz—for satellite communication systems operating band). Stable radiation patterns are observed for the operating bands with low cross polarization. The proposed design achieves hexa band characteristics during switching ON state of PIN diode located at reclined L‐shaped slot in the ground plane. Experimental characteristic of antenna shows close agreement with those obtained by simulation of the proposed antenna.     

Compact UWB flexible elliptical CPW‐fed antenna with triple notch bands for wireless communications

A coplanar waveguide (CPW)‐fed flexible elliptical antenna with triple band notched characteristics is presented in this article. The designed antenna consists of an elliptical patch and slots incorporated CPW feed line to cover the bandwidth requirements for ultra‐wideband (UWB) applications. The designed UWB antenna has a fractional bandwidth of about 166.19% (1.20‐13 GHz) with a center frequency of 7.1 GHz in simulation and about 170.10% (1.05‐13 GHz) with a center frequency of 7.025 GHz in measurement. The overall dimension of the proposed flexible antenna is 45 × 35 × 0.6 mm³. The triple notched bands are realized by designing with circular shaped split‐ring‐resonators (SRRs) and defected ground structure (DGS). According to the measurement, first notched band (2.0? 2.70 GHz) is generated for rejecting 2.4 GHz WLAN by introducing a single circular ST‐SRR on the radiating patch. The second notch (3.45‐3.80 GHz) is obtained by embedding another circular ST‐SRR on the patch to mitigate the interference of 3.5 GHz Wi‐MAX system. Finally, due to presence of DGS, third notch (5.15‐6.20 GHz) is produced which suppresses the interference from 5.5 GHz Wi‐MAX and 5.2/5.8 GHz WLAN systems. The proposed antenna offers excellent performance in different flexible conditions that confirm its applicability on curved surfaces for UWB systems.     

Mode investigation of parasitic annular ring loaded dual band coplanar waveguide antenna with polarization diversity characteristics

This document presents a dual band dual polarized coplanar waveguide (CPW) antenna with single port feed. Lower resonating band is circular polarized, while the upper band is linear polarized. A novel concept of realizing dual polarization by suppressing the undesired modes is introduced in this work. Orthogonal Even/Odd modes are excited at lower band and a phase difference of 90° is maintained between them. Hence, circular polarization behavior is realized for lower operating band. For upper band, Odd mode is suppressed by introducing step shaped modifications in the ground plane at left side of the feed line, resulting in linear polarized upper band. Dual band nature of the antenna is confirmed by 10 dB impedance bandwidth extending from 3.91‐5.31 GHz to 7.51‐8.72 GHz. Circular polarized nature of lower band is confirmed by enclosure of lower band by 3 dB axial ratio bandwidth extending from 4.01 to 5.59 GHz. Advantages of proposed antenna involves the use of single port feed for generating dual polarization performance along with compact antenna size.(30 × 30 × 1.6 mm³).     

Compact ultra‐wideband slot antenna with three notched‐band characteristics

A very compact ultra‐wideband (UWB) slot antenna with three L‐shaped slots for notched‐band characteristics is presented in this article. The antenna is designed and fabricated using a new stepped slot with different size, integrated in the ground plane, and excited by a 50 Ω microstrip transmission line. The stepped slot is used to minimize the dimensions of the antenna and to achieve an impedance bandwidth between 2.65 and 11.05 GHz with voltage standing wave ratio (VSWR) less than 2. The length of the stepped slot is equal to a quarter wavelength to create a resonance in the desired frequency. Three L‐shaped slots with various sizes are etched in the ground plane to reject three frequency bands in C‐band (3.7‐4.2 GHz), WLAN (5.15‐5.825 GHz), and X‐band (7.25‐7.75 GHz), respectively. The notched‐band frequency can be controlled by changing the length of the L‐shaped slot. The proposed antenna has a very small size (20.25 × 8 × 1.27 mm³) compared with previous works. The measured and simulated results show a good agreement in terms of radiation pattern and impedance matching.     

Dual‐band reconfigurable circularly polarized monopole antenna

A microstrip antenna with dual‐band reconfigurable circular polarization (CP) characteristics in Wireless Local Area Network (WLAN) and Worldwide Interoperability for Microwave Access (WiMAX) bands is presented in this article. The proposed antenna has a symmetrical U‐shaped slot with PIN diodes on the ground plane. The slotted ground generates a resonant mode for broad impedance‐band width, and excites contrary CP state at 2.45 GHz for WLAN and 3.4 GHz for WiMAX, respectively. Because switching the states of PIN diodes on the slot can redirect the current path, the CP state of the proposed antenna can be simply switched between the right‐handed CP and left‐handed CP. The proposed antenna has a low profile and a simple structure. Measured results of the fabricated antenna prototype are carried out to verify the simulation analysis. © 2014 Wiley Periodicals, Inc. Int J RF and Microwave CAE 25:109–114, 2015.     

A thin‐layer dielectric and metamaterial unit‐cell stack loaded miniaturized SRR‐based antenna for triple narrow band 4G‐LTE applications

This article presents the design of a miniaturized dual‐band antenna for long‐term evolution (LTE) application is presented. In the basic antenna design, split ring resonator was loaded in the radiating plane of the patch and frequency of resonance was further modified with the help of E‐shaped stub. The antenna has been fabricated using FR‐4 substrate and the measured dual bands at 2.11 and 2.665 GHz are found in a close match with the simulated data. By placing a thin dielectric resonator of permittivity ε _r = 10.2 and thickness of 1.27 mm, two closely spaced narrow bands are obtained at 2.217 and 2.28 GHz. A novel metamaterial unit‐cell having near‐zero refractive index is designed and mounted above the dielectric resonator. This stack configuration generates triple narrow frequency band in the LTE 2 GHz spectrum range. The overall size of the proposed antenna is 20 × 25 mm².     

A compact dual‐band zeroth‐order resonator antenna loaded with meander line inductor

A novel zeroth‐order resonator (ZOR) meta‐material (MTM) antenna with dual‐band is suggested using compound right/left handed transmission line as MTM. In this article, suggested antenna consists of patch through series gap, two meander line inductors, and two circular stubs. The MTM antenna is compact in size which shows dual‐band properties with first band centered at 2.47 GHz (2.05‐2.89 GHz) and second band is centered at 5.9 GHz (3.70‐8.10 GHz) with impedance bandwidth of (S₁₁ < ? 10 dB) 34.69% and 72.45%, respectively. At ZOR mode (2.35 GHz), the suggested antenna has overall dimension of 0.197λ_o × 0.07λ_o × 0.011λ_o with gain of 1.65 dB for ZOR band and 3.35 dB for first positive order resonator band which covers the applications like Bluetooth (2.4 GHZ), TV/Radio/Data (3.700‐6.425 GHz), WLAN (5‐5.16 GHz), C band frequencies (5.15‐5.35, 5.47‐5.725, or 5.725‐5.875 GHz) and satellite communication (7.25‐7.9 GHz). The radiation patterns of suggested structure are steady during the operating band for which sample antenna has been fabricated and confirmed experimentally. It exhibits novel omnidirectional radiation characteristics in phi = 0° plane with lower cross‐polarization values.     

Semi fractal three leaf clover‐shaped CPW antenna for triple band operation

This article presents a unique and compact coplanar waveguide (CPW) antenna that exhibits triband operation with circular polarization. The single antenna was designed to operate simultaneously in the following bands: WiMAX (3.3–3.6 GHz), wireless local area network (WLAN) (5.15–5.825 GHz), ITS (5.795–6.400 GHz), and ITU‐R (7.725–8.5 GHz). The realization of the triband antenna was achieved by using two semi fractal ring patches resembling the shape of a three leaf clover, and by introducing a pair of symmetrical L‐shaped slits in its ground plane. The antenna's physical parameters were investigated to fully understand their affect on the antenna's performance. The salient parameters obtained from this analysis enabled the optimization of the antenna's overall characteristics. The design concept was confirmed by fabricating the antenna prototype and measuring its characteristics. The proposed antenna has dimensions of 20 × 20 × 1 mm³. Measured results show the antenna exhibits circular polarization in WiMAX and ITU‐R bands, and linear polarization in the WLAN band. The antenna radiates omnidirectionally in the H‐plane, and approximately bidirectionally in the E‐plane. In addition, the antenna presents stable gain over the triband. © 2014 Wiley Periodicals, Inc. Int J RF and Microwave CAE 25:413–418, 2015.     

Dual ISM band printed antenna with omnidirectional radiation pattern and better radiation efficiency

Designing a high gain planar antenna on the low‐cost FR4 substrate is one of the major challenging tasks for the researchers. The omnidirectional radiation pattern is desired for 360° coverage. Both of these requirements have been addressed in this article. This article presents a dual band printed antenna designed on an FR4 substrate of 1.6 mm thickness. The proposed antenna operates in the ISM band of 2.4 and 5.8 GHz for the application of dual‐band WLAN/WIFI. The proposed antenna consists of a circular patch and ring‐shaped ground plane. The overall dimension of the antenna is 66 × 66 × 1.6 mm³. Excellent impedance matching and radiation efficiency for both the bands have been achieved. The proposed antenna shows omnidirectional radiation pattern at 2.4 GHz ISM band and nearly omnidirectional pattern along with high gain of 4.7 dBi at 5.8 GHz ISM band.     

A miniaturized ultra‐wideband planar monopole antenna with L‐shaped ground plane stubs

This article presents a miniaturized ultra‐wideband planar monopole antenna with an oval radiator. The proposed antenna is fed by a coplanar waveguide (CPW), and two L‐shaped stubs are extended from the ground plane of the CPW. This presented antenna is able to produce resonances in the lower frequency band and realize better impedance matching performance in the middle and higher frequency bands with the aid of the L‐shaped stubs. The antenna was built and tested. The total size of the proposed antenna is only 26 × 20 × 1.6 mm³. Its measured –10 dB impedance bandwidth is 10.1 GHz (3.1‐13.2 GHz). The measured far‐field radiation patterns are stable in the whole operating frequency band.