Transparent Antenna Research Articles

Retraction Note: A novel traffic load balancing approach for scheduling of optical transparent antennas (OTAs) on mobile terminals

Retraction Note: A novel traffic load balancing approach for scheduling of optical transparent antennas (OTAs) on mobile terminals

CPW fed optically transparent ultrawideband fractal MIMO terahertz antenna with meshed ground plane

Abstract An optically transparent UWB antenna element and its two-element pattern diversity MIMO configurations are presented in this paper. Three iterations of the quarter elliptical coplanar waveguide ground plane, rectangular microstrip feedline, and octagonal annular rings make up the antenna element. By metal meshing the ground planes and loading the radiator with several octagonal slots, the optical transparency is improved. It has a maximal achieved gain of 6.78 dBi and operates with steady radiation characteristics over the frequency spectrum of 4.52–28.64 THz (145.48%). The dimensions of the antenna element are 18 × 20.5 μm2. A metallic stub is positioned between two identical antenna components that are positioned orthogonally to one another to create a two-element pattern diversity MIMO antenna arrangement. The MIMO antenna is 20.5 × 42.5 μm2 in total. Its impedance bandwidth is 23.72 THz for port 2 and 22.68 THz for port 1. Using a rectangular stub results in an intraport isolation of >19 dB. Between the two ports, the planes in the radiation patterns have switched places. The diversity performance characteristics, which are considerably below the permissible limitations, are as follows: ECC > 0.01, CCL < 0.3 b/s/Hz, DG ∼ 10, TARC < 0 dB, MEG ∼ −3 dB, and 1≤VSWR_MIMO≤2. Compared to previously published structures, the suggested antenna structures have the advantages of smaller dimensions, a larger bandwidth, and improved optical transparency.

Investigation of optically transparent metasurfaces for gain improvement of an ultrawideband antenna for wireless body area networks and vehicular communications

Abstract Due to higher frequencies which cause signal deterioration, 5G enabled antennas are prone to substantial attenuation. To circumvent this problem, several access points, signal repeaters, and base stations must be installed closer together on building windows, streetlights, and other infrastructure. Optically transparent antennas preserve the aesthetics of the windows by offering the requirements for access points and base stations for providing network connectivity to the cars and pedestrians passing by those buildings. Here we report an ultrawideband (UWB) high gain optically transparent antenna operating from 4-12 GHz. Indium tin oxide (ITO) coated glass has been used as an optically transparent substrate for designing the antenna and metasurface. Two optically transparent metasurfaces have been proposed for band-stop filtering action across the UWB frequency range 4-12 GHz. In absence of the metasurface, the antenna operates in the frequency band ranging from 3.8 to 15 GHz. Average gain enhancement is 5.2 dB with radiation efficiency higher than 93% across the UWB frequency band from 4-12 GHz. Numerical simulations have been carried out for analysis of the proposed antenna and metasurfaces. These simulations have been validated by experimental measurements of the fabricated prototypes.

Transparent and Flexible Antenna With Polarization Reconfigurability Using EGaIn for Wearable Applications

Transparent and Flexible Antenna With Polarization Reconfigurability Using EGaIn for Wearable Applications

A High-Gain, High-Efficiency Transparent and Flexible Antenna for Vehicular Communication

A high-gain high-efficiency flexible and transparent film antenna in millimeter-wave is proposed in this paper. Comb structure which can be regarded as developed from the grid array structure is employed to mitigate the loss of the feeding network caused by the lossy metal mesh. The gain of the antenna has low sensitivity to the sheet resistance, which is promising in developing large-scale and high-performance transparent antenna. A large-scale ([Formula: see text]@28[Formula: see text]GHz) antenna is designed and fabricated using transparent metal mesh film with sheet resistance of 0.1[Formula: see text][Formula: see text]/sq and a thin PET film substrate. Bending measurement shows the antenna has excellent mechanical flexibility. A peak gain of 15.92[Formula: see text]dBi, radiation efficiency of 65.1%, optical transparency of 84% and 1,000-times bending are obtained. To the best of our knowledge, it is the highest gain and radiation efficiency flexible-transparent antenna reported thus far, which provides a glass-integrated antenna solution for vehicular communication.

Transparent antenna with RCS tunability based on graphene and metasurface in S band

In this paper, we propose a graphene-based radar cross section (RCS) tunable antenna that utilizes metal mesh and graphene, both of which are optically transparent. The graphene sandwich structure is introduced to replace traditional components like diodes, micro-electro-mechanical systems (MEMS), and varactors, acting as an electromagnetic wave controller and significantly simplifying the device's complexity. By applying different voltages, the electrical properties of graphene are altered, enabling the regulation of reflection, transmission, and absorption of electromagnetic waves. This not only modifies the antenna's pattern but also achieves a substantial reduction in out-of-band RCS. The radiation and scattering mechanism of the antenna is carefully elaborated. The numerical and experimental results match well, which validates the effectiveness of the proposed method. The optical transmittance of the device is 27.9% at 550 nm, and the out-of-band RCS reduction is 10.01 dB at 3.83 GHz. The transparent, RCS tunable antenna proposed has significant potential applications in optical and microwave stealth technology.

The Low-Attenuation Endfire Leaky-Wave State on an Optically Transparent Lossy Film

The development of high-performance optically transparent radio frequency (RF) radiators is limited by the intrinsic loss issue of transparent conductive films (TCFs). Instead of pursuing expensive endeavors to improve the TCFs’ electrical properties, this study introduces an innovative approach that leverages leaky-wave mode manipulation to mitigate the TCFs’ attenuating effect and maximize the RF radiation. Our finding reveals that the precise control of the mode confinement on glass-coated TCFs can create a low-attenuation window for leaky-wave propagation, where the total attenuation caused by TCF dissipation and wave leakage is effectively reduced. The observed low-attenuation leaky-wave state on lossy TCFs originates from the delicate balance between wave leakage and TCF dissipation, attained at a particular glass cladding thickness. By leveraging the substantially extended radiation aperture achieved under suppressed wave attenuation, this study develops an optically transparent antenna with an enhanced endfire realized gain exceeding 15 dBi and a radiation efficiency of 66%, which is validated to offer competitive transmission performance for advancing ubiquitous wireless communication and sensing applications.

Optically transparent coplanar wideband antenna for vehicular communication

SummaryThe presented state of the art is a novel coplanar optically transparent antenna designed to operate in extended GSM, L‐band, and UWB applications for vehicular communication. The presented radiator operates using a coplanar waveguide feed mechanism without a separate ground plane layer with a minimal conductive surface to enhance the transparency of the proposed antenna. The proposed antenna design has dimensions of 40 × 20 mm2, and a transparent material of soda–lime glass is used as a substrate with a dielectric constant of 7. The radiating element over the substrate is the conductive film fluorine‐doped tin oxide (FTO) with a sheet resistance of 7 Ω/sq. The operating frequency range of the designed antenna is from 0.86 to 14.45 GHz, which encloses the E‐GSM (900 MHz), L‐band (1–2 GHz), and UWB (3.1–10.6 GHz) frequencies. The peak gains at the operating frequencies are 1, 1.6, and 4.34 dBi, respectively. The designed antenna is fabricated and measured, and the performance metrics are plotted and compared. Since the transparent antenna is designed, the tendency of a substance to conduct light is measured as the optical transmittance, and it is calculated as 95% in the glass reference and 82% in the air reference.

A Polarization- and Frequency-Reconfigurable Transparent Liquid Antenna

A Polarization- and Frequency-Reconfigurable Transparent Liquid Antenna

Antena Tatasusun Grid Lut Sinar dengan Sel Suria Terpeka Pewarna (DSSC)

Wireless communication systems require electrical energy to operate and function. Whereas standalone applications require reliable power sources which can be realised by photovoltaic technology. Typically, photovoltaic cells and antennas are two separate devices. These devices compete for space in mobile or standalone systems, where available space is generally very limited. To address this issue, a combination of an antenna and a solar cell into a single device is needed. Integrating an antenna with a solar cell is challenging due to the importance of maintaining a compact, simple design while achieving optimal efficiency for both elements. This study focuses on designing a transparent grid array antenna integrated with Dye-Sensitized Solar Cells (DSSC) for Ku-band applications. The grid array design aims to improve antenna performance and is chosen for its suitability with the design and structure of the solar antenna device. The integrated antenna and solar cell were simulated using Computer Simulation Technology (CST) software at a frequency of 14 GHz for Ku-band applications. A prototype of the antenna and solar cell was fabricated, then tested and measured for the efficiency of both the antenna and solar elements. For the solar element, performance measurements were conducted using a halide lamp to mimic sunlight, with results presented in the form of current-voltage curves. In summary, by the end of this study, a transparent solar antenna for Ku-band applications was successfully designed with a gain exceeding 10 dBi. The solar cell’s performance showed an open-circuit voltage (V<sub>OC</sub>) of 0.6733 V, a short-circuit current density (J<sub>SC</sub>) of 2.06 mA/cm², a fill factor (f<sub>F</sub>) of 29.31%, and a power conversion efficiency (η) of 0.407%.

Hybrid additive-subtractive manufacturing of high-density copper-based flexible transparent circuits based on side-etch process

High-density flexible transparent circuits (FTCs) are widely used in 5G/6G flexible transparent antennas, wearable devices, flexible transparent electronics and other fields. However, the rapid iteration and upgrading of electronic circuits present significant challenges to the manufacturing of both high-density and high-precision circuits (especially copper-based circuits) at room temperature, in an efficient and flexible manner. Here, we employ the side-etching phenomenon, which is typically avoided, to propose a novel method for hybrid additive-subtractive fabricating high-density copper-based FTCs that combines electric field-driven (EFD) microjet printing and wet etching technology. Firstly, the customized photoresist mask was flexibly printed on the copper-clad flexible substrate by EFD microjet printing, and then the copper circuit with less than the mask resolution was obtained by the side etching process of the wet etching process. By optimizing process parameters and precisely controlling the speed of the side etching stage during the etching process, the manufacturing of high-precision copper-based FTCs with a minimum line width of 2.4 μm and a minimum pitch of 4 μm was achieved. The typical sample is manufactured with a resistivity of 4 × 10−6 Ω·cm, a sheet resistance of 3.58 Ω/sq at a transmittance of up to 87.65 % (including the substrate), and it exhibits excellent mechanical stability. The prepared high-density flexible transparent interdigital electrode has excellent sensitivity, and can detect the concentration change of dilute H2SO4 solution at a minimum of 1 nmol/L at a frequency of 100–10,000 Hz. This method provides a new solution for the fabrication of copper-based FTCs at room temperature with high efficiency and low cost, and shows a good prospect for industrial application.

Antena Tatasusun Grid Lut Sinar Gandaan Tinggi bagi Aplikasi Jalur-Ku

roducing compact devices for space technology. Transparent antennas are seen as the solution to this problem. With the presence of a transparent antenna, it can save antenna installation space as its transparency properties allow it to be integrated with solar technology. However, the use of transparent material on the antenna causes the antenna gain to be low due to the low conductivity of the material. When a low conductivity material is used it also causes the antenna efficiency to decrease. Therefore, modifications to the antenna design are needed to overcome such problems. This study aims to design a transparent antenna that can operate on Ku-band. The aim of this study is to identify the effect of transparent materials on conductivity, design a transparent antenna with an efficiency as low as 85% and design a grid array antenna to increase gain. The material verification test is carried out by making a comparison of the material in the antenna design simulation that works on Ku-band. The transparent antenna material selected is Indium Tin Oxide (ITO). Then, the design of the grid array antenna is carried out to increase the antenna gain hence for high efficiency. In this research, 8 loops grid array antennas increase the gain by 52% compared to reference antennas. The antenna meets performance requirements and can be integrated with solar panels to efficiently harness sunlight for electricity generation, while effectively transmitting and receiving wireless signals.

Additively Manufactured Stress-strain Dependant Frequency Reconfigurable Antenna for Pressure Sensor Applications

A novel additive-manufactured antenna for stretchable sensor application is designed, simulated and measured. The fully transparent antenna has air as a substrate and a conductive aluminium metal sheet as a patch. The layers are defined with thin Thermo Poly Urethane (TPU) material, as its flexible/stretchable property doesn't disturb the actual property of air. The air substrate is locked within the flexible TPU with a thickness of 200 microns, and the conducting patch is also dimensioned with the 3D printing method. The stretchable antenna is fabricated with 3D printing technology, considered a dielectric medium, and the conducting medium is a conducting aluminium sheet. Re-configurability is achieved with the pressure level applied over the air–substrate antenna. Hence, the minimal change in shape changes the dielectric constant, thus changing the antenna parameter and radiation pattern. The antenna achieves improved size and performance with a gain of 7.2 dB, a directivity of 7.574 dB, a radiation efficiency of 95.67 %, and a 12:509 front-to-back ratio. The fabricated antenna is tested for its resonant characteristics and radiation properties. This reconfigurable antenna can be used for various applications, including Wireless Local Area Network (WLAN) communication.

Transparent ionic liquid antenna based on multi-modes using multiple feeding structures

With the rapid development of modern wireless communication technology, there is an increasing demand for the functionality of the communication system carried by a single platform. To improve the utilization of the antenna, a multimode liquid antenna is proposed in this paper. The antenna is fabricated using 3D printing technology and mainly consists of a cylindrical dielectric resonator, a coaxial feeding structure, and a slot-coupling feeding structure. By hollowing out the middle of a resin container and filling it with low-loss ionic liquid with stable dielectric properties, a liquid dielectric resonator antenna (DRA) is formed. The various resonant modes (slot mode, HEM11δ, TM11δ, TM21δ, and TM31δ modes) can be excited by introducing different feeding structures. The operating frequencies and radiation patterns can be modulated by mode switching. Simulated and measured results show that the antenna operates in the frequency bands of 2.25–2.76 GHz (20.4 %) and 4.82–5.73 GHz (17.3 %), and the maximum gain can be up to 10.3 dBi. The proposed antenna structure avoids the complex RF control circuit design, which has various applications including 5G/6G communications, transparent electronic devices, and Internet of Things.

Transparent dielectric/metal/dielectric multilayer microstrip patch antennas for X and Ku-band

Optically transparent antennas are in high demand due to their critical role in healthcare, automotive and industrial sectors. These antennas face challenges in adjusting thickness for high optical transparency and also high conductivity for enhanced antenna characteristics. We mitigate the trade-off between optical transparency and antenna performance by pioneering the introduction of multiple sandwich structures in optically transparent antennas, for the first time in the literature, to the best of our knowledge. Three transparent multilayer antenna structures are designed as a rectangular patch antenna and fabricated on polycarbonate substrates. The multilayer structure consists of Ag layers sandwiched between layers of TiOx, SixNy, and ZnAlOx. Fabrication of the multilayer structures are verified by scanning electron microscopy (SEM). Optical transparencies of 85%, 73%, and 68% are achieved at a wavelength of 550 nm for one, two, and three layers of Ag, respectively. Scattering parameters and radiation patterns of the antennas are measured and simulated. For the antenna including triple dielectric/Ag/dielectric sandwich structure; peak gain, directivity and efficiency are obtained as 3.013 dBi, 8.072 dBi, and 37.5%, respectively. The agreement between measurements and simulations, together with the antenna performances obtained, validates our novel transparent antenna design.

FSS based high gain optically transparent MIMO antenna for Sub-6 GHz 5G mid-band applications

A novel optically transparent Multi Input Multi Output (MIMO) antenna design positioned on a Frequency-Selective Surface (FSS) for gain improvement while maintaining a simple fabrication procedure. Transparent conductive materials inherently exhibit higher sheet impedance due to lower conductivity, resulting in decreased antenna gain and radiation efficiency. To address this limitation, an optically transparent FSS is incorporated beneath the MIMO structure to improve radiation characteristics. Utilizing a Malinex substrate and a conductive silver oxide sheet, the 4-element MIMO design achieves both transparency and MIMO operability. The operational bandwidth spans from 3.09 GHz to 3.7 GHz, with a percentage bandwidth of 17.96 %, ensuring port isolation of over 20 dB. With the presence of the FSS, a consistent gain enhancement of approximately 3.46 dBi is achieved, with an average gain within the band reaching 4.56 dBi. The proposed design employs a simplified fabrication process while addressing aesthetic concerns and providing a solution to the existing issue of low gain in conductive metal oxide-based transparent antennas.

Mesh-based antenna with broadband transparency for dual-band shared-aperture array

Mesh-based antenna with broadband transparency for a dual-band shared-aperture array is proposed in this design. The low-radar cross section (RCS) frequency selective surface (FSS) cell is obtained firstly by combining the capacitive and inductive strips. It can be found that the electromagnetic (EM) transparent bandwidth across the high band (HB: n77) of the FSS can be enhanced by increasing in the number of strips. Then the low band (LB) antenna composed of low-RCS mesh-based elements is constructed. Remarkably, the EM transparent characteristic and the LB working performance can be individually controlled, avoiding time-consuming optimization. Subsequently, the LB transparent antenna is introduced into the array to eliminate the blockage effect on the HB antenna. The radiation patterns of the HB antenna are recovered well across the entire HB. Finally, the array prototype is fabricated and measured results show that the array covers a dual band of 1.7–2.7 GHz (45%) and 3.3–4.2 GHz (24%), showing stable radiation patterns in both LB and HB antennas. The average gains of the LB and HB antennas are 8.64 dBi and 8.58 dBi, respectively. The results verify that the proposed broadband transparent mesh-based antenna is attractive in the shared-aperture array.

Effect of annealing treatment of indium tin oxide thin films on film properties and transparent antenna properties

There is a growing demand for transparent thin film antennas to serve as access points for wireless communication that can be installed at any location without compromising visibility, while retaining the versatility of existing antennas. Although studies exist on indium tin oxide (ITO)-based transparent antennas, studies on the effect of thin-film process parameters on antenna properties are rare. In this study, we deposited ITO, which resonates at 3.3 GHz, using the facing target sputtering method with different thicknesses ranging from 400 to 2000 nm, from a typical thin film to a relatively thick film. ITO thin films deposited at room temperature were annealed in air at 200, 300, and 400 °C in an electric furnace. The optically transparent monopole antennas were fabricated using air-annealed ITO films. The effects of the annealing temperature on the film and antenna properties were investigated. A high radiation efficiency of 70.8 % was achieved while maintaining a transmittance of more than 70 % for a 2000 nm ITO film annealed at 400 °C. The results indicate that tailoring appropriate conductive film properties for desired transmittance is crucial to realize the expected antenna performance.

A broadband transparent antenna applied in indoor mobile communication system

AbstractThis paper proposes a broadband optical transparent antenna using a transparent conductor film on a transparent polyethylene terephthalate (PET) substrate. The planar wide‐slot antenna coupling fed by microstrip has a wide impedance bandwidth, so it is selected to design the transparent antenna. The upper surface of the PET substrate is a microstrip line with a fork‐shaped tuning branch, and the lower surface is a wide slot. They were made of transparent conductor film. Finally, a new capacitive coupling method is used to feed the transparent antenna. The transparent conductor film used in the antenna is metal mesh, which was developed by 3M company. The metal mesh with an open area greater than 80% to achieve high transmittance. The measured results show that the impedance bandwidth is 177% (0.30–5.0 GHz), and the gain of the antenna varies from 5.06 to 7.8 dBi over the entire frequency band. Therefore, it can be well applied to the current indoor mobile communication system.

Fabrication of an Optically Transparent Planar Inverted-F Antenna Using PEDOT-Based Silver Nanowire Clear Ink with Aerosol-Jet Printing Method towards Effective Antennas

We report the design, fabrication, and experimental characterization of an optically transparent printed planar inverted-F antenna (PIFA) operating at 2.45 GHz using the aerosol jet (AJ) printing method. The proposed antenna was fabricated using a clear conductive ink on glass and Delrin. The antenna exhibits a wide fractional bandwidth (FBW) of 20% centered at 2.45 GHz, with a peak realized gain of −3.6 dBi and transparency of ~80%. The proposed fabrication method provides a cost-effective and scalable solution for manufacturing transparent antennas with potential applications in wireless communication, sensing, and wearable devices operating at mmWave frequencies higher than 30 GHz.