Epsilon Negative Transmission Line Research Articles

Frequency reconfigurable antenna based on epsilon negative transmission lines

AbstractA novel coplanar waveguide (CPW)‐fed frequency reconfigurable antenna based on epsilon negative transmission line (ENG‐TL) is presented in this letter. By controlling the switch, the parameters of the ENG‐TL structure unit are changed, and the antenna can work on different frequency bands. By using varactor diode as a switch, the resonant frequency of the antenna continuously varies from 2.55 to 3.45 GHz while the bandwidth of 450 MHz keeps unchanged, which is suitable for n77 of sub‐6 GHz. But by using the PIN diode as a switch, the antenna can be reconfigured on three modes, lower single‐band (2.33–2.81 GHz), dual‐band (1.67–1.81 GHz and 3.32–3.60 GHz), and higher single‐band (3.98–4.22 GHz). The designed antenna is suitable for use in WLAN, DCS, and WiMAX (2.5/3.3 GHz). The simulated results are in good agreement with the measured results.

A Low-Profile and Compact Multi-Functional ENG-TL Inspired Antenna with Hybrid Polarizations for LTE/UMTS, WiMAX, and WLAN Applications

A novel low-profile, compact tri-band linearly and dual-sense circularly polarized (CP) antenna realized using via-less epsilon negative transmission line (ENG-TL) is investigated in this paper. The antenna miniaturization has been achieved by the zeroth-order resonance (ZOR) property of ENG-TL, which is actuated by connecting closed-loop octagonal ring radiator to an elliptical stub through a meandered-line structure. Circular polarization is accomplished by etching an L-shaped slot in the partial ground plane. The measured S11 result demonstrates that the proposed antenna features triple-band characteristics spanning from 2.42 to 2.50 GHz, 3.29 to 3.59 GHz and 5.43 to 5.55 GHz with centre frequencies of 2.46, 3.44, and 5.49 GHz, respectively. The antenna is offering linear polarization (LP) in the first and third bands while radiates left-handed CP in the + Z direction in the second band. An exceptional axial ratio (AR) of 0.062 dB has been achieved at 3.49 GHz with 3 dB axial ratio bandwidth (ARBW) extending from 3.35 to 3.67 GHz. This antenna offers an average simulated gain of 1.7 dBi across the CP band while 2.06, 1.75 and 3.67 dBi are acquired at 2.59, 3.53 and 5.62 GHz, respectively. Beside low-profile (0.013λ0 height) and miniaturized size (0.287λ0 × 0.205 λ0 ), intended antenna exhibits extended −10 dB impedance bandwidth, wide 3 dB AR bandwidth and reasonable radiation performance. It covers relevant frequency bands; therefore, it has the potential to be employed in 2.5 GHz LTE/UMTS, 3.5 GHz WiMAX, and 5.5 GHz WLAN applications.

An asymmetric CPW-fed ultra miniaturized epsilon negative triple-band antenna with improved gain using complimentary closed ring resonators

In this paper, an ultra-miniaturized triple-band antenna based on an epsilon negative transmission line (ENG-TL) approach is presented. The proposed antenna has a miniaturized electrical size of 0.247λ0×0.185λ0×0.019λ0 at 3.71 GHz which has been achieved by means of zeroth-order resonance (ZOR). This is recognized as an attractive technique to achieve compactness. It is observed from measured results that the proposed antenna is performing well over 3.63–3.81, 5.21–5.33, and 6.79–7.09 GHz. The novelty of this work lies in the fact that the peak gain has been improved by 1.73 dBi at the lowest order resonant mode. The antenna is able to exhibit measured peak gain of 1.97, 1.09, and 3.42 dBi in the broadside direction at 3.72, 5.27, and 6.92 GHz, respectively. Hence proposed antenna is suitable to work for Wi-MAX 3.5 GHz (3.4–3.8 GHz), WLAN/Wi-Fi 5.2 GHz (5.15–5.35 GHz), mobile/satellite (E-S) (6.875–7.075 GHz) applications.

Metamaterial Circularly Polarized Antennas: Integrating an epsilon negative transmission line and single split ring-type resonator

This article discusses the future possibilities and analysis of metamaterial (MTM)-based compact circularly polarized (CP) antennas for wireless applications. Here an effective method is introduced for designing a simple and efficient MTM CP antennas by integrating with an epsilon negative (ENG) transmission line (TL) and single split ring (SSR)-type resonator. For improving the radiation characteristics, a compact size artificial magnetic conductor metasurface (AMC-MS) without via is loaded with the intended ENG TL-based radiator antenna as a ground plane. The novelty of this kind of ENG TL-based CP antenna with AMC-MS is discussed for the first time in the literature and further image theory concept is applied for finding the driving point impedance. This kind of design is suitable for all frequencies by proper optimization and scaling. The radiating element of the intended antenna acquires a smaller area due to its zeroth-order resonance (ZOR) property with dimension of 0.26 λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> × 0.16 λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> at 3.5 GHz with an overall dimension with AMC-MS are 0.51 λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> × 0.51 λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> × 0.16 λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> at 3.5 GHz. The measured results of the antenna show an impedance bandwidth of 16.36% and a CP bandwidth of 11.93%. The antenna shows a gain of 5.62 dBic and average radiation efficiency of 72.1% along the frequency band.

Compact radiator antenna: A new approach to enhance the bandwidth using ENG-TL and C-CSRR mushroom meta-resonator

This work presents a new and efficient approach for enhancing the bandwidth and reducing the E-plane cross-polarization (X-pol) of an epsilon negative transmission line (ENG-TL) antenna with reduced size for working in 2.4 GHz Industrial, Scientific and Medical (ISM) band. The antenna consists of ENG-TL on which a curved meander line inductor is loaded for the generation of zeroth-order resonance mode. Subsequently, a miniaturized and low profile (0.06 λ0 × 0.06 λ0 × 0.013 λ0 at 2.44 GHz) circular-complementary split-ring resonator (C-CSRR) based mushroom meta-resonator is stacked over the ENG-TL antenna enhances the bandwidth twice without increasing any additional area. The proposed antenna provides a radiating element size of 0.17λ0 × 0.15λ0 excluding the feedline and total antenna dimension including ground plane is 0.17λ0 × 0.20λ0 × 0.025λ0 at 2.45 GHz. The measured results shows an enhanced impedance bandwidth (IBW) of 7.40%, an acceptable gain of 2.8 dBi, and X-pol value better than 35 dB is obtained for the E-plane. The antenna compactness, extended IBW, low X-pol levels, improved gain, high gain-to-area ratio, and acceptable radiation efficiency indicates that the proposed antenna is appropriate for working in 2.4 GHz (2.4–2.484 GHz) ISM band.

ENGTL based antenna for Wi-Fi and 5G

This article reported patch antenna functioning at Wi- Fi and 5G bands. Wi-Fi band (2.4 GHz) is obtained by loading Epsilon Negative Transmission Line (ENGTL) metamaterials into the patch radiating at 5G band (3.5 GHz). To acquire Circular Polarization (CP) at 5G band, conventional square patch is embedded with poly fractals. The experimental and simulated data are in close proximity. The obtained impedance bandwidth is 4.01% at Wi-Fi and is 10.68% at 5G band. CP bandwidth is 2.43% at 5G. This mix of ENGTL as well as fractals provides good compactness appropriate for portable gadgets

Coaxial‐fed high‐gain triple‐band zeroth‐order circularly polarized antenna using pseudo‐open termination and asymmetric unit cells

A coaxial-fed tri-band zeroth-order resonance (ZOR) circularly polarized antenna with higher gains for all the excited ZORs is designed and analyzed in this paper. Epsilon negative transmission line (ENG TL) and pseudo-open termination (P-OT) unit cells with different series capacitances (CS and CS1) resonate shunt ZOR (fsh) and two series ZORs (fse and fse1), respectively. Asymmetric unit cell concept is applied to ENG-TL and P-OT unit cells to create vertical and horizontal components, and the 90° phase shift is provided by the ZOR, resulting in circular polarization (CP). Left-hand CP (LHCP) is achieved by creating two 90° right bends to the extended stubs in ENG TL and P-OT unit cells. Higher gains for all the excited ZORs are achieved by shifting the shorting pins of ENG TL and P-OT unit cells far away from the center position. After fabrication, the measured resonances occur at 4.64 GHz (fsh), 4.04 GHz (fse), and 3.86 GHz (fse1) with fractional bandwidths of 1.62%, 1.73%, and 1.6%, respectively. The measured LHCP peak gains are 4.05 dBic (fsh), 3.85 dBic (fse), and 3.94 dBic (fse1). The average axial ratio obtained is less than 3-dB in the 10-dB fractional bandwidth of the proposed antenna.

High gain dual-band zeroth order omnidirectional circularly polarized antenna

A dual-band omni directionally circularly polarized zeroth order resonance (ZOR) antenna is proposed in this paper. Shunt ZOR (fsh) is excited by an Epsilon Negative Transmission Line (ENG TL), whereas Series ZOR (fse) is excited by two Pseudo-Open Termination (P-OT) unit cells. To resonate an omnidirectional fsh, ENG TL is required, while to resonate an omnidirectional fse, the two P-OT unit cells require similar series capacitances. Higher vertical and horizontal components are created by applying Asymmetric Unit Cells (AUCs) concept, in order to achieve Circular Polarization (CP) and high gain. The 90° phase is provided by the ZOR. By combining the feature of omnidirectional and CP at ZOR, omnidirectional CP is achieved at both fsh and fse. Since ENG TL and P-OT unit cells have two 90° right bends in the extended stubs, fsh and fse resonate with Left Hand CP (LHCP). The measured ZORs occur at 4.54 GHz (fsh) and 3.86 GHz (fse) with fractional bandwidths of 1.55% and 1.3%, respectively. The measured peak LCHP gains of the proposed antenna at fsh and fse are 3.34 dBic and 3.05 dBic, respectively. In the 10-dB impedance bandwidth range, the measured average axial ratio is less than 3-dB.

A Miniaturized Wide-Band Antenna Based on the Epsilon Negative Transmission Line for Wireless Communication Devices

A Miniaturized Wide-Band Antenna Based on the Epsilon Negative Transmission Line for Wireless Communication Devices

Triple-Band Zeroth-Order Epsilon-Negative Antenna Using Two Pseudo-Open Termination Unit Cells for C-Band Applications

In this letter, a triple-band zeroth-order-resonance (ZOR) epsilon-negative antenna using two series pseudo-open termination (P-OT) unit cells is proposed, for the case where shunt ZOR $({\boldsymbol{f}_{\boldsymbol{sh}}})$ is higher than series ZOR $({\boldsymbol{f}_{\boldsymbol{se}}})$ . Epsilon-negative transmission line (ENG TL) resonates a shunt ZOR, while the two series P-OT unit cells resonate two series ZORs ( ${\boldsymbol{f}_{\boldsymbol{se}}}$ and ${\boldsymbol{f}_{\boldsymbol{se1}}}$ ). Both the P-OT unit cells create different capacitances with the ENG TL to resonate ${\boldsymbol{f}_{\boldsymbol{se}}}$ and ${\boldsymbol{f}_{\boldsymbol{se}1}}$ . An electric field distribution vector is used to verify the resonances for zeroth order, and it is found that all the three resonances follow zeroth-order characteristics. The P-OT unit cells can be placed anywhere around the ENG TL to get proper matching. The measured resonances are 5.95 GHz $({\boldsymbol{f}_{\boldsymbol{se}1}})$ , 6.26 GHz $({\boldsymbol{f}_{\boldsymbol{se}}})$ , and 6.91 GHz $({\boldsymbol{f}_{\boldsymbol{sh}}})$ covering the satellite transmission frequencies of the C-band. The measured peak gains are 1.14, 1.39, and 2.19 dBi for $({\boldsymbol{f}_{\boldsymbol{se}1}})$ , ${\boldsymbol{f}_{\boldsymbol{se}}}$ , and ${\boldsymbol{f}_{\boldsymbol{sh}}}$ , respectively. ${\boldsymbol{f}_{\boldsymbol{se}1}}$ and ${\boldsymbol{f}_{\boldsymbol{se}}}$ have peak gain at the left and the right side of the $\varphi = {\text{0}^{\circ}}$ plane, respectively, while ${\boldsymbol{f}_{\boldsymbol{sh}}}$ has peak gains at both the right and the left sides of the $\varphi = {\text{0}^{\circ}}$ plane.

Co-axial fed triple-band and dual-band zeroth order antennas using pseudo-open termination unit cells for C-band applications

In this paper, a triple-band and dual-band zeroth order resonance (ZOR) epsilon negative antennas are proposed using two pseudo-open termination unit cells for the case where the shunt ZOR (fsh) is higher than the series ZOR (fse1). The epsilon negative transmission line (ENG TL) resonates fsh while the series ZORs (fse1 and fse2) are excited by the series capacitance of the two pseudo-open termination unit cells. If the series capacitances of the two pseudo-open termination unit cells are different then fse1 and fse2 are excited, else only fse1 is excited. fse1 and fse2 along with fsh results in triple-band ZOR antenna, while a single fse1 with fsh results in dual-band ZOR antenna. The pseudo-open termination unit cells can be placed anywhere around the ENG TL to get proper matching. All the resonances for both the antennas follow zeroth order characteristics which are verified using electric field vector. The measured peak gains of the triple-band ZOR antenna for fse2,fse1 and fsh are 1.14 dBi, 1.39 dBi, and 2.19 dBi, respectively, with dipole mode for fsh. For dual-band ZOR antenna, the measured peak gains for fse1 is 1.4 dBi, and fsh is 2.05 dBi, with dipole mode for fse1 and fsh.

Design of Zeroth-order resonance antenna array with a pair of DPS and ENG materials

This paper proposes one-dimensional antenna arrays of the four-element and the eight-element using composite materials. Firstly, the single element is designed to resonate at Zeroth-order using a pair of Double positive (DPS) and Epsilon negative (ENG) materials meta-structured transmission line (MTL). Secondly, three of 1:2 T-Junction power dividers and seven of 1:2 T-Junction power dividers based on micro-strip technology are designed for feeding the four-element and the eight-element array antennas, respectively. Finally, the proposed arrays are optimized using FEM-based simulation to operate at the frequency of 8,5 GHz. The simulated results show that both antenna arrays have Zeroth-order resonance (ZOR) property, in which the four-element array has a bandwidth spreading from 8.39 to 8.61 GHz and a maximum gain of 8.82 dB while the other one of the eight-element array is 8.39 – 8.60 GHz and 12.2 dB, respectively. The proposed array antennas can be used for wireless applications or mobile communications.

Metamaterial‐based circularly polarised antenna employing ENG‐TL with enhanced bandwidth for WLAN applications

This work explains the design and development of a low profile and compact single probe-fed metamaterial (MTM)-based circularly polarised (CP) antenna using the modified rectangular patch with two pairs of spiral strips and vias for 5.2/5.8 GHz WLAN applications. The intended CP antenna mainly consists of two pairs of radiators and each radiator is realised by using epsilon negative (ENG) transmission line (TL) to generate zeroth-order resonance. CP characteristics are achieved by placing two radiators for x -polarised wave are orthogonally aligned to the other two radiators for y -polarised wave. The antenna radiating element offers a compact size of 0.24λ 0 × 0.22λ 0 with a low profile of 0.04λ 0 at 5.5 GHz. To confirm the characteristics of the intended MTM CP antenna design, the designed antenna is fabricated and measured. Measurement results show that the antenna obtains -10 dB impedance bandwidth of 610 MHz (10.86%) which is 2.3 times larger than the standard microstrip patch antenna and axial ratio bandwidth of 140 MHz (2.54%) is obtained.

Miniaturised triple‐band antenna loaded with complementary concentric closed ring resonators with asymmetric coplanar waveguide‐fed based on epsilon negative transmission line

This study presents an open-ended triple-band miniaturised metamaterial (MTM) inspired antenna based on the epsilon negative-transmission line (ENG-TL). The zeroth-order resonance (ZOR) and first-order resonance (FOR) characteristics are implemented using the ENG-TL theory. The proposed MTM antenna consists of rectangular and square-shaped complementary concentric closed ring resonator (CCCRR) in the left and right half of the asymmetric coplanar waveguide (CPW) ground plane, respectively. The CCCRR generates an extra coupling capacitance and inductance, which help for improving the gain at ZOR mode and better impedance matching at higher-order mode. The resonance characteristic of the antenna is controlled by the shunt elements due to its open-ended boundary condition. The proposed triple-band MTM antenna offers measured -10 dB impedance bandwidths of 8.54% (1.12-1.22 GHz), 10.25% (2.22-2.46 GHz) and 35.75% (2.94-4.22 GHz). All these three bands show good impedance matching with appropriate gain and high radiation efficiency and also having an omnidirectional pattern in the xz- plane and dipolar type pattern in the yz -plane. The designed antenna shows an overall dimension of 0.11 λ 0 × 0.11 λ 0 × 0.006 λ 0 at ZOR frequency (1.16 GHz).

A novel uniplanar broadband antenna using coplanar stripline and epsilon negative transmission line

A novel uniplanar broadband antenna using coplanar stripline and epsilon negative transmission line

Compact and Wideband Disc Monopole Antenna based on Epsilon Negative Transmission Line for WiFi Applications

Compact and Wideband Disc Monopole Antenna based on Epsilon Negative Transmission Line for WiFi Applications

A compact frequency reconfigurable CPS‐like metamaterial‐inspired antenna

ABSTRACTA compact frequency reconfigurable coplanar stripline (CPS)‐like metamaterial antenna for WLAN and GSM applications is proposed in this article. A unique CPS structure is used to exploit the properties of metamaterial and it is being inspired from an epsilon‐negative transmission line (ENG‐TL). The main objective of using this structure is to simplify the geometry and to achieve frequency reconfigurable operation. The proposed antenna of size 40 × 40 × 1.524 mm3 with acceptable gain and radiation pattern will operate at two switching frequencies 1.8 GHz for GSM and 2.4 GHz for WLAN, respectively. Parametric analysis of the proposed antenna unit cell is performed using ADS in which by tuning the unit cell parameters WLAN band is achieved. To achieve the frequency reconfigurable property, RF PIN diode model is implemented on the antenna structure. Results of the prototype of antenna are compared with the simulated results. A close agreement is found between the measured and the simulated results. © 2017 Wiley Periodicals, Inc. Microwave Opt Technol Lett 59:596–601, 2017

A compact CPW-fed wideband metamaterial-inspired antenna for GSM, WLAN/Wi-Fi, and WiMAX applications

A compact coplanar waveguide (CPW)-fed wideband metamaterial-inspired antenna is designed and developed in this paper. The proposed structure is an asymmetric structure in which three rectangular stubs are employed between signal patch and CPW ground plane. It is demonstrated that these stubs provides lumped parameters of conventional epsilon-negative transmission line (ENG-TL). As an advantage of these stubs proposed antenna operates on 1.67–2.76 GHz with −10 dB impedance bandwidth of 49.2%. The proposed antenna having small electrical size of 0.17λ0 × 0.35λ0 × 0.01λ0 at fo = 2.21 GHz. The simulated average gain and radiation efficiency of the proposed antenna is 1.61 dB and 96.33% respectively throughout the bandwidth. Properties such as smaller electrical size, simpler design, consistent radiation characteristics, and ease of fabrication are making this antenna suitable for GSM, WLAN/Wi-Fi, Bluetooth, and WiMAX applications.

Epsilon-Negative Transmission-Line-Based Annular-Ring-Loaded Circular Microstrip Antenna With Improved Performances

A novel epsilon-negative transmission line (ENG TL)-based annular-ring-loaded (ARL) circular microstrip antenna (CMSA) is proposed in this letter. Compared to a conventional CMSA, the proposed structure offers improved impedance bandwidth by exciting the TM11 modes on both the driven CMSA and the coupled ENG TL-based annular ring. Due to the enlarged radiation aperture, the gain is correspondingly enhanced. Moreover, the proposed structure exhibits lower levels of radiation along the horizon and toward the backside as compared to conventional CMSA. The mutual coupling characteristics of the proposed antenna are also investigated, and the simulated results show that the E-plane mutual coupling between the proposed ENG TL-based ARL CMSAs decreases much more rapidly with spacing than that for conventional CMSAs. To validate the proposed concept, prototypes with a center operating frequency of 6.5 GHz are fabricated and tested. Good agreements are achieved between simulation and measurement.

BROADBAND EPSILON NEGATIVE TRANSMISSION LINE RESONANT ANTENNA WITH AIS LOADING

A metamaterial-based broadband antenna loaded with artificial impedance surface (AIS) is presented in this letter. Two metallic vias connect a Y-shaped patch to the ground plane. The patch, two metallic vias, and the AIS compose an epsilon negative (ENG) transmission line (TL). The asymmetry Y-shaped patch and the AIS bring about the first-order resonance (FOR) and second-order resonance (SOR) modes, which can be merged into one passband to yield a wideband property. The proposed ENG-TL resonant antenna has the advantages of compact size, wide bandwidth, and high gain, which can be applied to portable and handheld communication system.