In this study, an antenna with transparent super wideband CPW technology has been designed and built with the combination of solar panels for use in wireless communication equipment and systems that require mobile power. The transparency value of the antenna is 63.3%, which is an acceptable value for the optimal use of sunlight. The proposed antenna was designed and measured on a plexi-glass substrate with a dielectric constant of  Radio technology using the ultra wideband (UWB) has the ability to transfer data faster across small distances. UWB antennas are helpful for biomedical applications like imaging lung cancer5. Recently the use of SWB frequency range has received attention to the point that can cover and provide short and long-range data transmitting services8.Microstrip Antenna has recently attracted attention, due to its unique characteristics such as including its wide width, tiny size, straightforward construction, and ease of adaption. A range of 3.1–10.6 GHz was allocated to such means by (FCC) which is now familiar to ultra wideband (UWB) designers9. Furthermore, short-long-range transmission systems and the new generation of telecommunications can employ antennas with a broader bandwidth10.Super wideband (SWB) technology can be utilized for rapid sound and video transfer since it has a broad bandwidth and a large range of data capacity. Currently, this technology is employed for controlling and supervising purposes in both the private and military sectors. SWB in comparison to UWB has a bigger channel capacity, better timing accuracy, and higher image resolutionThe nominal bandwidth, which is the difference between Higher frequency (11. UWB antennas have been the subject of extensive research. Ultra-wideband (UWB) communications provide a large bandwidth with a high data rate, low transmission power with lengthened battery life and secure communications, and short pulse time modulation with reduced multipath fading. Also, UWB technology has many applications such as localization, imaging, radars, wireless body sensor networks, and short-range large bandwidth communications15. These works have focused on the microscopic SWB geometry and its use in contemporary communications. For example, In16 personal wireless UWB monopole antenna was designed for the Bandwidth of 135.2%, and the usage of 79.21%. In17 the author designed a practical antenna that may be utilized for WIMAX/WLAN/ISM and other wireless applications with a bandwidth of 153.22% and a bandwidth fraction of 86%. In18, a monopole antenna with a Bandwidth of 3.1–10.6 GHz and 82.22% is the efficiency of the higher band has been designed for wireless. In19, a UWB antenna with two circles of connected lines was designed in a frequency Band of 3.85–0.55 GHz with a 90.1% efficiencies. Finally, in20 a monopole antenna with a zigzag shape for an access to 102% is designed to be employed in communication processes.Here 21. A slotted waveguide antenna with a radiation rate of 88% was presented. A slotted waveguide antenna with a radiation rate of 88% was presented. The proposed antenna has a small size of 30 mm × 35 mm, a simple geometry, and the excitation is launched through a 50 Ω microstrip feed line22. The use of fractal geometry in antenna design provides a good method for achieving the desired miniaturization and multi-band properties. In this communication, a multi-band and broad-band microstrip antenna based on a new fractal geometry is presented. The proposed design is an octagonal fractal microstrip patch antenna. The results show that the proposed microstrip antenna can be used for 10–50 GHz frequency range, i.e., it is a super wideband microstrip antenna with 40 GHz bandwidth23. All of these antennas employ a monopole micro strip that has a UWB bandwidth of 40 GHz (50–10 GHz), which can easily be made by precisely constructing a microwave and solar cell combination that is useful for satellite and ground applications. For ground purposes, it has led to expanding the automatic integrated system in driver-less cars24.An antenna with line (TL) loaded, compact, ultrawideband (UWB) square slot antenna is a radiation efficiency of 79.21% has also been designed for personal wireless communication systems. The square slot is a microstrip line fed and loaded with an array of periodically perturbed TLs to achieve a UWB response from 2.1 to 11.5 GHz25 This antenna was made of an expensive luminous conductor film AGHT-4 with a minimum visible light transfer of 75%. The suggested antenna cannot be utilized in multi-band or broadband communication systems since it is only designed for a single frequency band with an impedance bandwidth of 4.3%. In26, a super-wideband antenna based on a propeller shaped printed monopole with CPW feed is presented. The enhanced bandwidth is obtained by modifying the disk of a conventional circular disk monopole to resemble a propeller. This design produces an extremely wide impedance bandwidth from 3 to 35 GHz with an impedance bandwidth ratio of 11.6:1. The gain of the proposed antenna varies from 4 to 5.2 dB. In27, a MIMO antenna with a circle ring of coating of silver-tin alloy radiation patch over a layer of plexi-glass is recommended. This antenna features a 3.7 GHz WLAN and a 2.4 GHz WIMAX. The employment of silver-tin-alloy as a radiator has a negative effect on radiation performance, in addition to the high cost and complexity of production, and the researchers have proposed a solution in the form of MIMO in this study to solve this issue. In28, a printing technique on glass is used. the mask-covered glass uniformly with the photolithography technique. Finally, due to the thickness the of the glass, no negative effects happened to the Pyrex glass while printing ink of silver. The practical accuracy of fabrication is 0.02 mm for the mask and etching mechanism. the metallic pattern screen is plated with silver on the glass.Recently a significant volume of research has been done in designing solar antennas with smaller sizes and the capability of producing DC voltage while transferring microwave signals. As an example we refer to the microstrip transparent antenna inIn this paper, we present a transparent super wide band antenna with solar-cells. At the first step we designed the antenna on a FR4 substrate. Next, transparent plexi-glass was used as a transparent substrate. In previous works, metal oxides is used for the construction of radiation part, which can interfere with the antenna radiation function. In our case, a layer of copper sheet that is precisely cut by CNC laser is used. This antenna can be used in satellite with its solar cells. It can also be utilized in vehicles glasses, wireless CCTV cameras and wherever there is a need for electrical power supply beside antenna. We will discuss this in the future.We design this antenna with CPW feeding Technology. As shown in Fig. mentclass2pt{minimAs shown in Fig. As a method of achieving this goal based on prior research Fig. C, we attFigure In figure Fig. In this section, we use a substrate from FR4 to plexi-glass the antenna will be transparent and allow the light to pass through it. Plexi-glass has high resistance against different climates. It is cheap, and therefore a good choice to be used as a lucid substrate. We used the usual plexi-glasses available in the market, with In Fig. In Fig. Figures According to the diagram in Fig. 30.The efficiency of the antennas in Fig. With respect to the availability of plexi-glass in different sizes in the market, we have used different sizes of plexi-glass 33\documenFor calculating the correlation coefficient, we choose the wide band Gaussian pulse as the input transmitter signal for the antenna, As shown in Fig. 35. In other words, if in practice the group delay is approximately constant it provides the characteristics for the acceptable PULS, Eqs. 22\documen38. Group delay waves are related to weal Bandwidth application.In Eq. , \docume39.Two similar antennas across each other with 30 cm distance. in parts a, b and c, takes values 0, 45 and 90 degrees respectively according to Fig. The graph showing the phase variation of Fig. Multiple-input-multiple-output (MIMO) is a method of wireless communication systems using multiple transmission and receiving antennas. With this feature, the user can use two or more antennas to reduce the sending and receiving information delay and increase the speed of communication using the specified channel. In this section as it is shown in Fig. 40. This measure can be computed using complex patterns 42. When 44. This technique is also discussed in45. MEG in46 is calculated from the results of the S parameter using Eq. . Lower TARC values indicate better antenna performance and improved efficiency. TARC values is verified using a single phase and randomly, on the interval [0–180] degree46. Figure 46.TARC is defined as the square root ratio of the total reflective Power divided by the root of the total power in a multi-port antenna system51. This value is less than the standard practical 0.4 Bit/S/Hz for the antenna working frequency and this fact confirms the high throughput of the proposed antenna.MIMO antennas, for using huge amount of data in a limited channel and supplied channel capacity is the maximum data rate through which through which the signal can pass using MIMO channel. CCL is an important criterion for analyzing and verifying channel capacity functionality. The CCL parameter provides details of the wasting capacity of the systems channel along the correlation effect. CCL is calculated numerically using Eqs.  and 21)21). The In previous researches, metal oxide has been used to make the radiating part of the antenna. Due to its low conductivity, this oxide creates interference in the operation process and radiation pattern of the antenna. In addition, the difficulty of production and costly manufacturing have been among the problems of this method. We have used copper sheet for the antenna’s ground and radiating sections due to its availability, low cost, and convenience of fabrication, as well as the fact that lines with low resistance attenuate signals less than lines with high resistance. These sheets are cut by CNC laser machine with 0.02 mm precision. Since copper sheets come in a variety of thicknesses, the simulation shows that the with a thickness of 0.04 mm for a sheet, is the most suitable thickness to take into account for antenna building. Also, according to the simulation results, the thickness of Plexi-glass is considered to be 1 mm. Figure Figure 6.The proposed antenna is compared with previously reported ultra wideband (SWB) antennas in terms of electrical dimensions, operating frequency range, operating bandwidth (BW), bandwidth aspect ratio (BDR) peak gain and substrate material. Table wing Eq. :Table 4AHere In this paper a transparent antenna with CPW structure was designed and verified for ultra-band width application and fine tuning parameters for impedance bandwidth expansion is implemented. A ground plane and radiation patch with several cuts were used for the sake of antenna transparency and impedance bandwidth. The proposed structure for the antenna reduces to BDR 2450 which represents a comparatively high BDR in comparison with the previously proposed structures. This fact confirms the wide bandwidth and compactness of the antenna. The proposed structure guarantees that the simulated frequency ranges from 2.9 to 29.2 GHz The measured frequency range of the produced sample antenna is matched with the simulated sample. The interest of the antenna ranges from 1 to 8.1 dB. The antenna efficiency is overall the working frequencies. The antennas specification is verified and checked with and without solar cells. This verification shows that solar panels have a tiny negative impact on antennas gain and have a huge positive effect on antennas bandwidth. Electrical dimensions, operating bandwidth (BW), bandwidth ratio (BWR), gain peak and beneath antenna substance were compared with the previous designs and schemas. We observed that the proposed antenna is performing optimally in comparison with other designs. Furthermore, to ensure that antenna is performing optimally we have tested and checked the antenna using a MIMO schema. At this step all of the vital parameters of the MIMO antenna such as electrical correlation coefficient (EEC), mean effective gain, diversity gain, total active reflection and channel capacity loss (CCL) is checked and the acquired appropriate/optimal values verify the optimal performance of the antenna in MIMO form. Due to these advantages, the designed antenna is applicable in wireless communication systems such as L, S, C, X, Lca, K, Ka and Q. In this article, transparent plexi-glass is used as a transparent substrate. The use of a transparent substrate, which has made the antenna transparent, and this feature has made it possible to use solar cells in the antenna. In addition to improving the performance of the antenna and the main characteristics of the antenna, the use of Plexiglas substrate has reduced construction costs by 10 times compared to other substrates. This substrate can be introduced as a cheap substrate with high resistance and high transparency. In previous papers, for the construction of the radiation part, metal oxides were used which, could interfere with the antenna radiation function. In this antenna, a layer of copper sheet that is precisely cut by a CNC laser is used. This antenna can be used in satellites with solar cells. It can be applied in vehicles glasses, Wireless CCTV cameras and wherever there is a need for an electrical power supply beside an antenna. The wideband transparent antenna has potential applications across various sectors including remote energy supply, wearable technology, and solar energy recovery. A plausible application for implementing a super wideband transparent antenna on a solar cell for self-driving cars is to enhance the vehicle's connectivity and communication systems. with regards to wearable technology, embedding the transparent antenna in clothing or other wearable devices could facilitate seamless connectivity without the need for bulky wires or antennas. This would be particularly useful in remote areas where traditional power sources are not available. Additionally, the transparency of the antenna would allow more light to pass through to the solar cell, further increasing its efficiency. This technology could be used in various applications such as in space exploration, where solar power is often used as a primary source of energy .Supplementary Information.


The manuscript presents a novel approach to designing and fabricating a stretchable patch antenna designed for strain sensing and the wireless communication of sensing data at the same time. The challenge lies in combining flexible and stretchable textile materials with different physical morphologies, which can hinder the adhesion among multiple layers when stacked up, resisting the overall stretchability of the antenna. The proposed antenna design overcomes this challenge by incorporating a lattice hinge pattern into the non-stretchable conductive e-textile, transforming it into a stretchable structure. The innovative design includes longitudinal cuts inserted in both the patch and the ground plane of the antenna, allowing it to stretch along in the perpendicular direction. Implementing the lattice hinge pattern over the conductive layers of the proposed patch antenna, in combination with a 2 mm thick Polydimethylsiloxane (PDMS) substrate, achieves a maximum of 25% stretchability compared to its counterpart antenna without a lattice hinge design. The stretchable textile antenna resonates around a frequency of 2.45 GHz and exhibits a linear resonant frequency shift when strained up to 25%. This characteristic makes it suitable for use as a strain sensor. Additionally, the lattice hinge design enhances the conformability and flexibility of the antenna compared to that of a solid patch antenna. The realized antenna gains in the E and H-plane are measured as 2.21 dBi and 2.34 dBi, respectively. Overall, the presented design offers a simple and effective solution for fabricating a stretchable textile patch antenna for normal use or as a sensing element, opening up possibilities for applications in the communication and sensing fields. Recent adaptations of smart systems for on-body wearable applications for human well-being, health monitoring, and observing human movements have grabbed attention ,2. FolloThe use of multifunctional devices also minimizes the problem of complex wiring, which is prone to damage and is required to acquire sensory data in wearable smart systems. Similarly, a wearable system with multifunctional devices can solve integration challenges with any garment ,21. ConsThis manuscript presents a fully textile-based, flexible, and stretchable antenna. Our proposed work focuses on fabricating a stretchable textile patch antenna for strain sensing and communication, which can be used in wearable applications. Furthermore, we present a novel and simpler method for fabricating a stretchable antenna on a non-stretchable e-textile fabric. Our research follows an adapted and simplified antenna design, making it an interesting progression. The antenna is realized using a non-stretchable turned stretchable e-textile fabric, accompanied by a transparent, flexible, and stretchable non-conductive polydimethylsiloxane (PDMS) substrate.This paper is organized as follows: In recent years, several stretchable antennas have been developed ,23,24. TVarious conductive materials have been employed to construct stretchable antennas, including Silver-Polydimethylsiloxane (Ag-PDMS) composites, metal nanowires, and liquid metal alloys. However, the poor conductivity of these materials remains a significant concern ,27,28. WTo fabricate a stretchable patch antenna, one option is to use conductive and dielectric materials that have a stretchable character. However, this way of constructing a stretchable patch antenna is difficult, as neither the conductive and dielectric materials will not be compatible in their stretchability. One will offer more stretchability than the other when sandwiched together in a patch antenna shape. Alternatively, the antenna design itself can be modified to allow for an extra amount of stretching, or a combination of both approaches can be employed. Each method of fabricating a stretchable antenna has its advantages and limitations. In recent developments, in an example where an antenna design was modified for a patch antenna to obtain stretchability, optimally patterned 3D structures such as serpentine and helical coils made from conventional non-stretchable materials like copper foil were utilized for fabricating stretchable patch antennas ,17. ThesOther recent advancements in the field of stretchable antennas include the use of serpentine structures , materials such as silver nanowires (AgNWs), and liquid metal alloys ,32,33,34Our research proposes a simpler, easy, and novel method for fabricating stretchable textile-based antennas, based on transforming plain conductive layers of a patch antenna into lattice hinge design (LHD) conductive layers. The structure of an LHD and its design parameters are shown in One significant advantage of using e-textiles with a lower surface resistivity is the reduced cost of integrating antennas into garments. Additionally, our proposed LHD-based stretchable antenna fabrication method offers minimal change in its electrical performance while providing stretchable characteristics. The distinguishing feature of our research from the existing stretchable antenna literature lies in the simpler and novel technique employed to create a fully textile stretchable antenna. This work can be further extended by exploring different design patterns to convert non-stretchable materials into stretchable ones.The selection of both conductive and non-conductive/dielectric materials for fabricating a stretchable antenna was primarily based on the factor of stretchability. In the recent literature, a variety of dielectric materials commercially available, such as Ecoflex, Solaris, and PDMS, have been utilized to fabricate stretchable antennas ,38,39,40® Technik-tex P130 +B by Statex Produktions, Bremen, Germany) was chosen because of its highly stretchable nature and lowest possible surface resistivity among the other commercially available knitted structures. This silver-plated knitted fabric is composed of 78% polyamide and 22% elastomer, with a coating of 99% pure silver. However, this fabric has a surface resistivity of 2 Ohm/square (Ω/sq) and a conductivity of 909 S/m, significantly lower than those of a standard copper metal sheet with a conductivity of 5.96 × 107 S/m. Both a basic patch antenna prototype (without the LHD) and an LHD patch antenna prototype were simulated and fabricated to observe their behavior upon stretching. While both antenna prototypes exhibited stretchability, the stretchability of the LHD antenna prototype was particularly better when experienced by hand. The fabricated antenna prototypes are depicted in Among the various fabric geometries, knitted structures are the most suitable for fabricating stretchable textile antennas due to their superior stretchability compared to woven and non-woven structures. This research begins with the selection of the knitted conductive materials to be used in the stretchable antenna fabrication. Initially, a commercially available, two-way, stretchable, conductive, silver-coated, knitted electrotextile  with better electrical conductivity and transformed it into an LHD for use in the stretchable antenna. A higher electrical conductivity is essential for any conductive material used in antenna fabrication, as it minimizes electrical losses and contributes to the improved EM characteristics of the antenna. ® Technik-tex P130 +B and Shieldex® Kiel +30 conductive fabrics.As the selected Shieldex®, Washington, DC, USA) was prepared in a custom-made mold for fabricating the stretchable textile antenna. The PDMS was composed of two liquid components: the base and the curing agent, which were mixed in specific proportions (10:1). When the two components were thoroughly mixed, the mixture cured into a flexible and stretchable elastomer. The 10:1 mix ratio allowed for better control over the hardness and modulus, enabling improved stretchability and flexibility. With a higher Young’s modulus of 1.5 MPa, PDMS demonstrated a better conformation with human skin for on-body applications and could withstand high deformations.Among a variety of dielectric materials commercially available, as mentioned above, PDMS was selected. The choice of PDMS as the dielectric antenna substrate was made as it is a transparent, stretchable, and hyperplastic polymer. It offers a higher viscosity of 3500 centipoise, which strengthens the interfacial bonding between the dielectric substrate and the e-textiles. A 2 mm thick layer of the PDMS substrate  and loss tangent (tan δ) values needed to be known to simulate the final antenna prototype. To do so, an iterative process was employed, which involved changing the Er value and observing the corresponding change in the resonance frequency of the antenna at a 2.45 GHz operating frequency using CST Studio Suite 2019, an Electromagnetic and Multiphysics simulation software. During the antenna simulation, both the properties of the selected conductive and dielectric PDMS materials were defined in the CST simulator to characterize the dielectric PDMS substrate. A simple rectangular microstrip patch antenna was simulated using the specific dimensions (length and width) of the 2 mm thick PDMS dielectric substrate, with arbitrary values of Er and tan δ at the 2.45 GHz operating frequency. Subsequently, the antenna was physically fabricated. To compare the simulated results with the experimental results, the resonance frequency was measured using a Vector Network Analyzer (VNA). The difference between the resonance frequencies of the simulated and experimental antennas was initially observed. The Er value in the CST simulator was then adjusted accordingly to match the simulated and experimental resonance frequencies. Once the resonance frequencies coincided with the new Er value, it was considered to be the actual value for the PDMS substrate. The presence of substrate losses was reflected in a broader and less pronounced resonance peak in the return loss graph, with the depth of the peak indicating the level of the substrate losses. Similarly, the value of tan δ was manipulated to match the depth of both the simulated and experimental resonance frequency peaks. In this way, the dielectric PDMS substrate was characterized. The measured characteristics of the stretchable PDMS dielectric substrate at a frequency of 2.45 GHz are listed in The resonance frequency method was adopted to characterize the dielectric PDMS substrate ,41. The The microstrip patch antenna topology was chosen for its numerous advantages in wearable radio frequency applications. Planar patch antennas offer simplicity in design, lightweight construction, and easy integration into garments ,43. WhenIn wearable applications, the dimensions of the antenna play a crucial role in determining its operating resonance frequency. For the design of the LHD-based patch antenna, the length and width of the patch were calculated using the transmission line model. The physical dimensions of the antenna, particularly the patch length, were adjusted to achieve resonance at the desired frequency of 2.45 GHz during simulation.The antenna design and simulation were conducted at an operating frequency of 2.45 GHz using the CST Studio Suite. The overall dimensions of the proposed LHP stretchable antenna in this research work are listed in 3 (width × length × depth) using a Computer Numeric Control (CNC) machine. This mold was utilized to pour the liquid PDMS polymer, allowing it to take on the accurate shape specified above, as depicted in A mold was designed using AutoDesk Fusion, a modeling software, to shape the liquid PDMS polymer. The mold was created from high-density polyethylene with precise dimensions of 80 × 70 × 2 mm® Kiel +30 e-textile fabric using a laser cutter. Next, the liquid PDMS polymer was prepared and placed in a desiccator to remove any air bubbles. Once prepared, the PDMS was poured into a pre-prepared mold with specific dimensions and placed in a curing chamber set at a temperature of 60 °C. A few minutes into the curing process, the surface of the liquid PDMS polymer started to solidify, becoming sticky. At this stage, the pre-cut sample of the conductive ground plane was carefully placed onto the partially cured sticky surface of the PDMS polymer and left to continue curing. The PDMS polymer typically took around 50 min to fully cure at 60 °C. Once fully cured, the PDMS polymer sample, with the conductive ground plane layer adhered on one side, was peeled off from the mold. Finally, a thin layer of fresh liquid PDMS polymer was applied to the other side of the fully cured PDMS polymer, and the patch layer was deposited, leveled, and left to cure once again at 60 °C. Through these process steps, the fabrication of both solid patch antenna samples and LHP patch antenna samples was carried out. ® Kiel +30 e-textile fabric facilitated better bonding with the PDMS polymer.The antenna fabrication process involved several steps. Initially, samples of the LHD for both the patch and the ground plane were cut from the ShieldexDuring the fabrication process, special attention was given to aligning the LHD links in the patch with the links in the ground plane. This alignment ensured that uniform stretchability was achieved throughout the fabricated antenna.Considering the limitations of the chosen conductive e-textiles and the fabrication method involving laser cutting, it was determined that the clearance between adjacent links in the LHD should not be less than 2.5 mm on the materials chosen for our research work. The laser cutting of the selected e-textile fabric in an LHD provided flexibility but reduced its strength when the clearance was decreased to below 2.5 mm. On the other hand, reducing the clearance between adjacent links significantly increased the flexibility and stretchability of the e-textile, albeit at the expense of its strength. The length of the lattice hinge link played a critical role in the stretchability of the antenna, with a longer link length resulting in better stretchability. During the simulation, a trade-off was observed between the length of the link and the electrical performance of the antenna at the chosen resonance frequency. The width of the link should be minimized to maximize the available area for inserting more links into the patch and ground plane. Increasing the number of links in the conductive layers of the antenna enhanced its stretchability.® Kiel +30 e-textile are depicted in ® Kiel +30 e-textile fabric are shown in Furthermore, rough antenna samples were fabricated with varying thicknesses of the PDMS substrate, ranging from 1.5 mm to 3 mm. It was found that thinner substrates provided better overall stretchability but reduced the strength of the antenna when stretched, and vice versa. Therefore, a 2 mm thick PDMS substrate was finally chosen, as it sustained a reasonably good deformation during stretching. Front and back views of the fabricated solid patch antenna using the Shieldex® Kiel +30 e-textile fabric did not exhibit any stretchability, despite the stretchable nature of the PDMS substrate. However, in contrast, the experimentally fabricated LHP patch antenna using the Shieldex® Kiel +30 e-textile offered some stretchability. Additionally, the antenna showed improved flexibility when manually handled. Each antenna prototype was soldered with an SMA connector with a 50 Ω characteristic impedance to provide power to the antenna through the microstrip feed line. It should be noted that the microstrip feed line in the LHP antenna was kept solid, without lattice hinge links, to ensure a robust connection to the SMA connector and enable a uniform flow of the input power.Based on the observation, the experimentally fabricated solid patch antenna using the ShieldexThe experimental characterization of the fabricated antenna prototype involved the use of a custom-made setup to evaluate its EM performance under uniaxial stretching. The EM performance of the antenna was assessed by measuring its S11 parameter at varying strain ranges. The S11 parameter represents the reflection coefficient of the antenna, indicating how well it can radiate power at a specific operating frequency. The power that was not reflected at the antenna’s interface to the transmission line was either radiated or resistively dissipated. However, due to the good conductivity of the materials used, the dissipation was assumed to be very low, which will be confirmed by the radiation pattern measurements further in this paper. By measuring S11 during the stretching process, the antenna’s performance under different strain conditions could be analyzed and evaluated. The radiation patterns of the fabricated antenna prototype were measured in an anechoic chamber, as depicted in To measure the S11 of the antenna at different strain ranges, uniform uniaxial tension was applied using laser-cut wooden block spacings. These block spacings represented the amount of applied strain and were placed between the main wooden clamps of the custom-made setup. By adjusting the spacing, different elongation ranges were achieved, allowing for the measurement of S11 at varying strain levels. To validate the experimental results, the antenna prototype was also simulated at varying strain levels using the CST studio suite. The simulation results were compared with the experimental measurements to assess the correlation between both the simulated and experimental results. This comprehensive characterization process helped to understand the antenna’s behavior under strain and validate the effectiveness of the proposed design and fabrication methods.To see the effect of a change in the electrical properties  of the LHP stretchable patch antenna upon uniaxial stretching, the same custom-made tensile setup, as mentioned in ® Kiel +30-based solid patch antenna. Both the simulated and experimental results, in terms of S11, showed resonance at the 2.45 GHz operating frequency. This indicated a good agreement between the simulated and measured data. On the other hand, ® Kiel +30-based stretchable patch antenna. The reflection coefficient measurements showed dual frequency peaks at 2.18 GHz and 2.45 GHz, both in the simulated and experimental data, when the LHD was implemented.To measure the S11 of the fabricated antenna prototypes, a Vector Network Analyzer (VNA) was used. Before conducting the S11 measurements, a calibration process known as the short-open-load-through (SOLT) calibration was performed using a Keysight 85052D calibration kit. The SOLT calibration helped to establish a reference for accurate measurements by compensating for the inherent reflections and losses in the measurement setup. These results demonstrate the similarity between the simulated and experimental data, validating the accuracy of the simulation model and the successful fabrication of the stretchable patch antenna.During the design and simulation of the LHP stretchable patch antenna, it was observed that the resonance frequency shifted towards the lower end when the LHD was incorporated into the patch and ground planes of the solid antenna. This shift in resonance frequency indicated the possibility of tuning the antenna to the desired operating frequency of 2.45 GHz by changing the solid antenna into the LHD antenna. To achieve the same frequency tuning in conventional antennas, the resonance frequency can be adjusted by changing the length of the patch or the thickness of the substrate. In our research, the focus was to design and simulate the LHP stretchable patch antenna at an operating frequency of 2.45 GHz. To achieve the desired resonance frequency, the length of the newly formed LHP stretchable patch antenna was adjusted compared to the patch length of the solid antenna. The incorporation of the LHD allowed for the transformation of a solid patch antenna into a stretchable and tunable LHP antenna suitable for wearable applications.The simulations and measurements revealed two resonant frequencies, 2.18 GHz and 2.45 GHz for the LHD-based stretchable patch antenna. The current distribution on the LHD-based stretchable patch antenna is illustrated in It can be observed from The effect of applied strain on the change in the resonance frequency and reflection coefficient values for the fabricated LHP stretchable patch antenna at different levels of elongation is illustrated in ® Kiel +30-based solid patch antenna at a 2.45 GHz resonance frequency in the (a) E-plane and (b) H-plane. The experimentally measured realized gains were 2.95 dBi and 2.98 dBi in the E-plane and H-plane, respectively. The illustrations shown in ® Kiel +30-based LHP stretchable antenna at a 2.45 GHz resonance frequency in the (a) E-plane and (b) H-plane. The experimentally measured gains were 2.21 dBi and 2.34 dBi in the E-plane and H-plane, respectively.® Kiel +30-based LHP stretchable antenna, a slightly higher level of back radiation can be observed in both the E-plane and H-plane compared to the Shieldex® Kiel +30-based solid antenna. This is attributed to the presence of lattice hinge links in the ground plane, which reduced its overall conductive area and led to increased back radiation. However, the differences in the gains between the solid and LHP antennas were minimal, indicating that the stretchable nature of the LHP antenna did not significantly affect its radiation performance.In the radiation patterns of the Shieldex® Kiel +30-based solid patch antenna did not exhibit stretchability despite the stretchy nature of the PDMS substrate. However, it did provide a slightly higher realized gain compared to the LHP stretchable antenna. The solid antenna remains flexible and can still be used effectively in wearable applications. On the other hand, the Shieldex® Kiel +30-based LHP stretchable patch antenna compensated for this with enhanced flexibility and could stretch up to 25% in addition. The LHD significantly improved the overall flexibility and stretchability of the fabricated antenna, making it suitable for wearable applications where conformability and stretchability are desired.The Shieldex® Technik-tex P130 +B  and Shieldex® Kiel +30  in search of better stretchability and electrical performance. The former antenna exhibited enhanced stretchability but had lower electrical performance. On the other hand, the latter antenna had a better electrical performance but limited stretchability. To address this trade-off, the LHD was incorporated into the non-stretchable antenna, improving its overall stretchability without significantly compromising its electrical performance.In summary, our research aimed to design, fabricate, and characterize a multifunctional stretchable patch antenna operating at a resonance frequency of 2.45 GHz. The antenna was intended to serve as both a communication device and a strain sensor. Two antenna prototypes were fabricated using different conductive materials: Shieldex® Kiel +30 demonstrated stretchability of up to 25% under uniaxial tensile strain before it went to rupture. The antenna showed a linear trend in its resonance frequency shift as the applied strain increased up to 20% but continued to resonate without reaching a point of rupture. This characteristic makes it suitable for use as a strain sensor, in addition to its communication capabilities. The realized antenna gains at the E-plane and H-plane were measured as 2.21 dBi and 2.34 dBi, respectively.The fabricated LHD stretchable patch antenna made from ShieldexOverall, our research successfully developed a multifunctional stretchable patch antenna at a 2.45 GHz resonance frequency with strain-sensing capabilities, providing conformability, flexibility, and stretchability for wearable applications while maintaining satisfactory electrical performance.


The single unit of the proposed design consists of a modified L-shape rectangular radiator with Z-shape slot loaded DGS. The defected ground structure is optimized through machine learning algorithms to achieve the maximum ARBW (output) by Right Shifting (RS) and left shifting (LS) the DGS and obtaining input features. The performance metric for ANN with ADAM optimizer was found to be optimal with MSE and R2 of 0.99 and 0.82, respectively. ANNs can leverage gradient information to guide the optimization process. This enables faster convergence towards optimal solutions compared to popular GAs and PSO, which are often gradient-free optimization methods. The MIMO configuration is achieved by creating a mirror image of the single unit about the x-axis. The salient features of the proposed design are (a) Impedance bandwidth (IBW) of 3.0–4.2 GHz covering the n77/n78 band, (b) 3-dB axial ratio bandwidth (ARBW) of the 2.6–3.9 GHz (c) Port-1 is generating RHCP while Port-2 is generating LHCP, results in polarization diversity. Different diversity performance parameters  are in the optimum range confirming the proposed configuration as a suitable design for a MIMO radiator.In this communication, a planar dual port multiple input multiple output antenna of size 1.2λ Various performance enhancement methodologies are discussed in the literature to cater the requirements of fifth generation wireless technologies9. Recent articles in the research literature have described a variety of MIMO antenna designs for 5G networks operating below 6 GHz23. But compared to their forerunners, these antennas either have a narrower bandwidth or higher mutual coupling. However, the antenna size may grow due to reduced mutual coupling and fewer ECCs between nearby antenna components. Therefore, these factors are crucial in the design of MIMO antennas for handheld electronics. As a result, one of the challenges of antenna design for portable devices is to include several antennas inside the device despite the limited space available while yet ensuring enough isolation. Several techniques are available in the literature to reduce the mutual coupling between the antenna elements in MIMO29.Due to the increasing number of consumers and the rapid advancement of wireless communication technology, higher throughput, and channel capacity have become crucial needs. Combining several antennas into a single portable device would prove to be a viable option, which will ultimately result in improving the caliber of the communication network and the transmission rate. As a result, the technology known as multi-input, multi-output (MIMO) plays an essential part in the center of activity for 5G research. Throughout the last few years, those working in the telecommunications industry have seen considerable change in the telecom sector. The first generation of mobile communication systems was introduced in (1G). Following the success of 1G, 2G, and 3G, the current standard is 4G. At the moment, 5G is on the verge of becoming a reality. A considerable number of countries have already shown leadership by initiating the rollout of the 5G network. Two potential spectrums might be used for wireless communication using the 5G standard. The first is the range of frequencies below 6 GHz, while the second is the range of microwave frequencies or mm-waves. Since the Sub-6 GHz spectrum is widely accessible in existing wireless communication networks and may be used for 5G without requiring extensive hardware upgrades, service providers are contemplating using this frequency band for the first 5G deployments. The sub-6 GHz band consists of n77/n78/n79: (3.3–4.2)/(3.3–3.8)/(4.4–5.0) GHzOn the other side broadband, circularly polarized (CP) antennas have been more in demand in recent years due to the proliferation of high-speed wireless networks. Given its ability to mitigate both polarization mismatch and multipath interference, CP antennas have garnered considerable interest. As per the conceptual definition, a CP is produced by two orthogonal resonant modes with the same amplitude and a 90-degree phase difference. Broadband CP antennas are attractive in several different wireless systems because of the need to support large data rates. In contrast to modern microstrip antennas, conventional microstrip antennas often suffer from narrow bandwidth and a high axial ratio. The challenge of creating a small antenna with a high CP bandwidth has so emerged as a significant area of study. 5G requires small CP antennas. Wireless and satellite applications employ circularly polarized antennas. Due to benefits including suppressing multi-path losses and addressing polarization mismatch of transmitter and reception antennas, CP antenna research is vital.30. Sharma et al. proposed Lasso (least absolute shrinkage and selection operator), k nearest neighbour, and artificial neural network to improve the double T-shaped monopole antenna31. Gao et al. determined the microstrip patch antenna’s resonance frequency using semi-supervised learning-based Gaussian Process Regression (GPR)32. Sarkar et al. proposed a band-notch UWB slotted antenna and predicted the notch frequency using a multi-adaptive neuro-fuzzy model33. Ranjan et al. built five machine-learning models to propose a UWB-compatible CPW-fed monopole radiator. Predictions match simulations and measurements34.Wireless networks rely on antenna design. Thus, a simple antenna parameter design and optimization approach is needed. High-frequency simulations take significantly longer as technology reduces antenna size and increases antenna characteristics like frequency and complexity. Machine learning-based models are commonly utilized to overcome these difficulties. These models estimate antenna performance quickly. Antenna design may employ various machine-learning principles and methodsTo cater the present fifth-generation requirements of portable wireless communications devices, circularly polarized multiple input and multiple output antennas with high isolation, high gain, and optimum diversity performance are the best solutions. MIMO will provide high channel capacity and data rates with limited power while a circularly polarized feature of the antenna enables it to compensate for the multipath fading, and provide polarization-dependent freedom as compared to the linearly polarized antenna.In this proposed work, an ML-optimized dual port printed MIMO antenna with wide ARBW is reported for the 5G NR band of n77 (3300–4200 MHz) & n78 (3300–3800 MHz). The mirror image placement of the two antenna elements of the MIMO antenna is producing polarization diversity . The antenna has a simple design, and its excitation is provided via a 50-Ω feedline. The design that has been suggested is implemented on a Rogers 5880 laminate that has a thickness of 0.8 mm. The suggested design's main characteristics are as follows: (a) an impedance bandwidth (IBW) of 3.0–4.2 GHz covering the n77/n78 band; (b) a 3-dB axial ratio bandwidth (ARBW) of the 2.6–3.9 GHz; and (c) Polarization diversity as a consequence of Port-1 producing RHCP and Port-2 creating LHCP. The simulated and measured findings agreed well, indicating that the suggested design might be a good contender for 5G communication owing to its low ECC, high DG, and high isolation between the radiators. The results of optimization using machine learning are quite similar to those obtained by simulation and experimentation.3, printed on Rogers RT duroid 5880 high-frequency laminates of a thickness of 0.8 mm and relative permittivity of 2.2. The top surface of the substrate consists L-shape radiator with a rectangular stub, fed with a 50 Ω transmission line while the back portion of the substrate is printed with a copper sheet engraved with a Z-shape slot working as the defected ground surface. The suggested MIMO antenna is obtained by replicating the unit cell in mirror orientation about the x-axis which as a result increases the dimension to 120 × 60 × 0.8 mm3.The geometrical layout and fabricated photographs of the proposed MIMO antenna are shown in Figs. 1 = 12 mm, L2 = 7 mm, L3 = 6 mm, L4 = 18 mm, L5 = 20 mm, L6 = 20 mm, Lf = 11 mm, Ls = 60 mm, W1 = 4 mm, W2 = 6.5 mm, W3 = 6 mm, W4 = 7.5 mm, W5 = 29 mm, W6 = 8 mm, W7 = 32 mm, W8 = 11 mm, Wf = 1 mm, Ws = 120 mm, thickness of substrate = 0.8 mm.The dimensional specifications of the proposed antenna with geometrical parameters are mentioned as: L11| (dB) and Axial ratio (dB)  are presented and a comparative investigation is carried out in terms of |S1), and feed position (W1). The quarter wavelength stub is playing important role in getting the wider axial ratio bandwidth. From the perusal of Fig. 1) is moving towards the higher frequency range, and a small shifting effect is observed for higher cutoff frequency  shifting is presented in Fig. 1 = 1 mm to W1 = 5.5 mm result in a shift of the lower cutoff frequency (f1) in the lower frequency range while marginal shifting is observed in case of the higher cutoff frequency. Further, in the case of 3-dB ARBW variation, the optimum value is achieved in the case of W1 = 4 mm only  and left shift (LS) of the Diffracted ground structure as shown in Fig. i is the axial ratio obtained from different combinations (in the range of − 2 mm to + 2 mm) of spatial movement of the DGS structure as shown in Table Further, an artificial neural network (ANN) is incorporated to improve the predicted outcome. The independent parameters X35:The objective function in CATBoost is defined as follows2 value of 0.73 indicates that the model fits the data satisfactorily.The test value in the proposed methodology is the axial ratio calculated for each Right Shift (RS) and Left Shift (LS) of the defected ground structure (DGS) as shown in Table Since the axial ratio of the antenna is dependent on the right and left shift of the DGS, therefore, for optimized axial ratio and to improve the CP performance of the antenna, the ANN algorithm is further incorporated in this work. Since ANN is unaffected by overfitting, it can be a better substitute for GBM where overfitting is constrained by using an early stopping parameter. Such a parameter improves overfitting but restricts the potential of GBM. Therefore, ANN with three different optimizers is further exploited to improve the predicted outcome.36:Stochastic gradient descent (SGD) is a popular optimization algorithm for training machine learning models, particularly in cases where computing the gradient of the loss function concerning the model parameters is computationally expensive. Instead of computing the gradient based on the entire dataset, which can be time-consuming and memory-intensive, SGD uses a single example  to compute the gradient, which makes the algorithm much faster. The stochasticity in the name refers to the fact that the algorithm uses randomness in the data to compute the gradient, rather than the full data set. In SGD the regularization hyperparameter θ updated by37:Root Mean Squared Propagation (RMSprop) is a gradient descent optimization algorithm used in machine learning. It is similar to the more popular stochastic gradient descent (SGD) algorithm, but with a different approach to the learning rate. In RMSprop, the learning rate is adaptively adjusted for each weight, rather than being kept constant as in SGD. The main idea behind RMSprop is to divide the learning rate for a weight 2 value with the same ratio of the training set and test sets. Further, it can be conferred that the RMSprop algorithm performed better in the prediction of axial ratio as compared to the SGD algorithm.38:It is common practice to use an optimization technique like ADAM (Adaptive Moment Estimation) while instructing a neural network. The technique employs moving averages of the parameters to continuously estimate the second raw moments of the gradients, and the word adaptive in the name alludes to the fact that the algorithm adjusts the learning rates of each parameter depending on the previous gradient information. The equation for ADAM is given by2 value with a ratio of the training set and test sets of 80:20 are better than SGD and RMSprop. Further, it can be conferred that the ADAM algorithm performed better in the prediction of axial ratio as compared to other ANN optimizers.Further, the performance parameter of each of the algorithms is shown in Table Figure X) or vertical (EY)) must have the same amplitude but be rotated by 90 degrees concerning one another. Figure X), and one vertical (EY). Strong EX and EY components are formed as a direct result of the currents that are generated on the stubs. Because the quarter wavelength stubs are oriented asymmetrically, the ground plane's current distributions are likewise altered simultaneously with this process. In the suggested radiator, a quarter wavelength stub functions as an electric dipole while an inverted Z-shape slot loaded ground plane acts as a magnetic dipole, creating orthogonal electric field components. Quarter annular stub adds λ/4 to microstrip route latency. This extra route delay creates a CP wave at 3.5 GHz by shifting the phase of orthogonal electric field lines by 90 degrees (phase difference = 2π/λ × path difference)39.To generate circular polarisation, two electric field components  and their phase difference (EX-Ey) to help you better understand the proposed antenna's circular polarization. For the impedance bandwidth of 3–4.2 GHz that was found, the ratio of field components is close to 1 and the phase difference is about 90°, which explains the planned antenna has a large circular polarization bandwidth.Figure The MIMO configuration under consideration is achieved through the replication of the antenna element of the unit cell in a mirror image pattern along the x-axis. In the context of MIMO designs, the grounding sections of individual elements were interconnected to maintain uniform voltage levels across the entire antenna system.11| and |S22| plots are not in coherence for parallel orientation as compared with the mirror orientation. Similarly from Fig. Figure Figure 11|, |S12| and axial ratio variations. By looking at Fig. 40:i.The initial procedure involves orienting the proposed test antenna in the XZ plane, while maintaining a polar angle of θ = 0° and an azimuthal angle of ϕ = 0°.ii.Determine the desired frequency interval for measuring the axial ratio.iii.At this juncture, it is recommended to rotate the horn antenna from its initial position of 0° to a full 360° rotation in order to attain co-polarization. Take down the dBm readings from the spectrum analyzer showing how much power the test antenna was able to receive at each angle.iv.Since circular polarization is a subset of elliptical polarization, it is clear that the two are related. Now the main axis represents the highest power level and the minor axis represents the lowest. Since power is measured in decibels (dB), you may calculate it by subtracting the lowest power (major axis) from the greatest power (minor axis). Subtracting two numbers yields the axial ratio.This section focuses on three key points: (i) comparing simulated and observed findings (ii) calculating diversity performance (iii) examining how well the proposed two-port MIMO antenna stacks up against the other antennas that have been published in the literature. Figure Figure Figure i.The proposed antenna is mounted in broadside direction.ii.Standard Gain antenna on the other side (whose gain is known to us i.e. GT)iii.Now find out S21 at each frequency points which give (PR-PT).iv.Path losses are finding out by v.Find out cable loss by directly connecting the transmitting and receiving cable.In order to measure the gain of proposed antenna, Two Antenna Method is used [B]. The steps involved in the measurement of antenna gain are as follow:Now, finally used Friss Equation formula given as follow:H and EV value for different angle at specific frequency. Now, LHCP and RHCP radiation pattern is obtained by using formula mentioned in Eqs. (41.The suggested antenna’s circular polarization plots for ports 1 and 2 in left-handed (LHCP) and right-handed (RHCP) variants are shown in Fig.  in Eqs.  and 7)  H and EVThe different diversity performance parameters like envelope correlation coefficient (ECC), diversity gain (DG), channel capacity loss (CCL), mean effective gain (MEG) and total active reflection coefficients (TARC) are studied, investigated and calculated to understand the independency of each port and multi-channel propagation performance of the proposed MIMO antenna.42. Equations  43.The simulated and calculated ECC values for the proposed radiator are shown in Fig. 45.In wireless communication systems, the quality and dependability of a MIMO antenna may be determined by its diversity gain. Therefore, the DG of the MIMO antenna has to be high at least 10 dB) within the frequency region that is permitted. The DG is determined by using the ECC value in a calculation, and the resulting answer may be found in Eq.  is defined as the ratio of the MIMO antenna's received power to the isotropic antenna’s received power, making it a significant diversity metric for MIMO antennas. A MIMO antenna’s performance improves when the ratio of MEGquations  and 13)1/MEG2, i1, MEG2 and MEG1/MEG2 plot for the proposed radiator is mentioned in Fig. 1/MEG2 is nearly equal to 0 dB.The MEG48.TARC is an additional crucial component that must be considered while determining the most efficient multiport antenna design. It illustrates the proportion of power that is reflected to the total power that is incident. For a two-port MIMO antenna the value of this parameter is determined by using the formula shown in Eq. 48.14\doc11 and S22, respectively. S12 and S21 stand for the isolation between the two ports. The calculated TARC of the proposed antenna is shown in Fig. The reflection coefficients for ports 1 and 2 are denoted by S0 calculated at the lower cut-off frequency), axial ratio bandwidth, sense of polarisation and gain/radiation efficiency. According to the information that is provided in Table 38. When compared to the other described antennas in Table 32. Moreover, the proposed model's diversity performance parameters are optimal in comparison to those of other MIMO antennas.Table 1/MEG2 ≈ 0 dB, and CCL < 0.5 bits/s/Hz of the proposed MIMO antenna is incorporated in simulated and measured form. Novelty justification of the proposed design is also presented in form of a comparative investigation in terms of different vital parameters with the previously reported antennas. Three different machine learning models are used to optimize the CP in the proposed work. The machine learning-based predicted values and simulated/ measured values are found in the agreement.In the presented work machine learning model-based optimized dual port MIMO antenna with RHCP/LHCP features are investigated for fifth generation new radio frequency range of n77(3300–4200 MHz) & n78 (3300–3800 MHz) band applications. Impedance bandwidth (IBW) of 3.0–4.2 GHz and 3-dB axial ratio bandwidth (ARBW) of the 2.6–3.9 GHz is reported for the proposed model. A detailed description of the CP mechanism attainment and polarization diversity features of the proposed antenna is discussed with the help of surface current distribution and radiation pattern plots. The pertinent information about the different diversity performance parameters such as ECC < 0.005, DG > 9.99, MEG


The proposed antenna is composed of an inverted L-shaped antenna with decoupled elements to cover 4G (2000–2600 MHz), and a planar inverted-F antenna (PIFA) with a J-slot to cover 5G (3400–3600 MHz and 4800–5000 MHz). Furthermore, to achieve the purposes of miniaturization and decoupling, the structure adopts a feeding stub, shorting stub, and outstanding floor, additionally adding the slot to the PIFA, to generate additional frequency bands. Due to the advantages such as multiband operation, MIMO configuration for 5G communications, high isolation, and a compact structure, the proposed antenna design is attractive for 4G/5G smartphones. The antenna array is printed on an FR4 dielectric board, measuring 140 × 70 × 0.8 mm The latest smartphones generally support 5G networks, which can provide mobile phone users with voice calls and mobile data services with less delay and greater bandwidth to meet users’ daily communication needs. Thus, 5G technology has been widely used in the smartphone antenna industry ,2,3. HowRecently, several MIMO antennas for mobile devices have been proposed. In ,7, an 8-In this paper, a tri-band 8-element MIMO antenna is proposed. Besides the ability to cover the 5G bands n78 and n79, it can also yield the 4G band (2000–2700 MHz). In addition, it can exhibit desirable impedance matching and isolation (>10 dB) across the three operating bands, and the envelope correlation coefficient (ECC) of the 8-element antennas is also calculated . HFSS is3, and the 4G antenna is located on a 15 mm long clearance area on the top, which prominently reduces the coupling between units. The 5G antennas are evenly arranged on both sides of the back panel of the mobile phone. The unit is a planar inverted F antenna, so no additional headroom is required. A new current path is constructed through the loading gap, so that the antenna can work in two frequency bands.In this paper, by optimizing parameters such as feeder width, protruding ground size, antenna spacing, and antenna width, length, and height, the parameters such as return loss, isolation, and the radiation pattern of the antenna in the working frequency band can be optimized.2. The specific size is shown in The 4G antenna consists of four parts: the feeding stub, short-circuit stub, protruding ground, and neutral line. The clearance area used is 15 × 70 mmEach antenna unit is composed of a feed stub and a short-circuit stub. The short-circuit stub generates a new resonance frequency point outside the working frequency band of the feed stub, which expands the antenna’s working bandwidth. By optimizing the length of the short-circuit end stub, it can be adjusted. The width of the feeding line and the shorting line are both 1.5 mm, and the characteristic impedance of the microstrip line is 50 Ω at this time.The protruding ground structure and the neutral line loaded between the antenna elements can improve the isolation between the antenna elements. Among them, the width of the protruding ground is 10 mm, and the distance between two short-circuit branches is 7 mm. The overlapping width between the short-circuited stub and the protruding floor is 1.5 mm, and the capacitive coupling generated can reduce the resonant frequency of the antenna and achieve the purpose of miniaturization.When the antenna unit has no short-circuit stubs and only monopole radiation, refer to antenna 1 in By adding a short stub, such as reference antenna 2 in Adding a neutral line and a protruding ground structure between the antenna units can improve the isolation between the antenna units: the coupling between the antenna and the protruding ground can reduce the coupling between the antenna units, and the conduction current on the neutral line can be coupled with the radiation The current is neutralized to achieve a decoupling effect.Due to the 1.5 mm wide overlap between the short stub and the salient ground, the resulting capacitive coupling shifts the resonant frequency of the short stub to a lower frequency, from 3200 MHz without a salient ground to 2100 MHz. The operating frequency of the monopole is 2500 MHz, and the added short-circuit stub can expand the bandwidth of the antenna.The electric field distribution of the antenna when it is working is shown in When the frequency is 2100 MHz, the feed stub excites the short-circuited stub through coupling, and the short-circuited stub radiates outward. Due to the short distance of the short-circuited stub, the coupling degree of the antenna reaches the maximum at the resonance frequency of the short-circuited stub at 2100 MHz. However, due to the addition of additional decoupling stubs, the maximum coupling degree is only 14.7 dB. When the operating frequency is 2500 MHz, it mainly radiates outwards from the feeding stubs, as shown in By adjusting the length of the terminal branch of the short-circuited stub, the resonant frequency of the short-circuited stub can be tuned, as shown in By adding short-circuit stubs and decoupling structures to the antenna, the working bandwidth, return loss, and coupling degree of the antenna unit are optimized. The scattering parameters of the antenna are shown in 2. There are three symmetrical 5G antenna units on each side of the metal backplane with a spacing of 23 mm, and the distance between the antenna units on both sides is 19 mm from the edge of the backplane.The MIMO antenna proposed in this chapter contains a total of six 5G antenna elements. Since the 4G antenna uses a clearance area with a length of 15 mm, the area used by the 5G antenna is 125 × 70 mmThe antenna structure is a planar inverted-F antenna loaded with slots, as shown in 2. A J-shaped slot with a length of 13.5 mm and a width of 1 mm is loaded on the plane of the PIFA antenna. The gap creates a new current path that allows the antenna to operate at two frequencies.The height of the PIFA antenna in this chapter is 5 mm, the distance between the feed point and the short-circuit point is 2.5 mm, and the plane size is 14.2 × 5 mmFrom the feed point to the open end along the J-shaped slot, a longer current loop is formed; from the feed point directly to the open end of the PIFA antenna, a shorter current loop is formed. Tuning the lengths of the two current loops separately can adjust the resonant frequency points of the high and low frequencies. For the antenna in this chapter, the stub is extended by 0.75 mm at the end of the J-shaped slot to optimize its resonant frequency, as shown in 2, and the distance between the feed point and the short-circuit point is 2.5 mm; a resonant frequency point can be generated at 4000 MHz, and the working bandwidth of the antenna is 700 MHz, which is well matched, and it is shown as Antenna 1 in The prototype of the antenna is a common PIFA antenna, the height of the antenna is 5 mm, the plane size of the antenna is 15 × 3 mmL of the open stub end in reference antenna 2. As L increases, the resonant frequency of the longer branch of the antenna moves to lower frequencies, as shown in L = 0.75 mm, the resonance frequency of the antenna shifts from 3600 MHz to 3500 MHz.Since the antenna is expected to operate at 3500 MHz, the resonant frequency of the longer branch of the antenna can be tuned by optimizing the length After optimization, the two operating frequencies of the PIFA antenna are 3400–3600 MHz and 4800–5000 MHz, which can cover the frequency bands of n79 and n78. The electric field distribution of the antenna is shown in W1 between the antenna unit and the edge of the floor, the better the radiation effect. However, the increase of W1 will make the antenna spacing W2 too small, which will increase the coupling between adjacent antenna elements. By optimizing the values of W1 and W2, the radiation performance of the PIFA antenna can be optimized and the isolation between antenna elements can reach more than 10 dB.The PIFA antenna does not require a clear space but radiates equivalently through the reflection image of the floor, so a relatively complete floor is required under the PIFA antenna. Therefore, the distance between the antenna unit and the edge of the floor will affect the radiation performance of the antenna. As shown in W1 increases, that is, when antenna 3 and antenna 5 are far away from the edge of the floor, the impedance matching and radiation performances of the antenna are optimized. However, due to the relative reduction of W2, that is, the distance between the antenna elements is reduced, the coupling between the antenna elements is too large, and the isolation is less than 10 dB. When W1 is reduced, the matching of the antenna gradually deteriorates but the isolation between elements is optimized. After a comparative analysis, the value of W1 is 19 mm and W2 is 23 mm. Currently, the matching of each antenna is good, and the isolation between units is greater than 10 dB.When Based on the above analysis, the basic structure and distribution position of the 5G antenna elements have been determined. After simulation, the scattering parameters of the six-element MIMO antenna are shown in The envelope correlation coefficient is one of the important parameters of the MIMO antenna, which reflects the diverse characteristics of MIMO. The ECC value of the low-frequency band of the antenna is required to be less than 0.5, and the ECC value of the high-frequency band is less than 0.4. The MIMO toolkit in the HFSS software can calculate the envelope correlation coefficient of the antenna according to the scattering parameters obtained by simulation. It can be seen in The cell phone antenna needs to be close to the human hand or head when it works, and the human body as a conductor has a greater influence on the radiation performance of the antenna.Through the hand or head model simulation, we can illustrate the influence of the human body on the antenna radiation performance, whether the antenna can work normally when the phone is held or talking. As in From the simulation results, the coupling between 4G antenna units is enhanced due to the reflection of the head or hand, the isolation is reduced to 12 dB, and the return loss of 4G antenna is increased. This is not because the matching of the antenna is optimized, but because the head absorbs part of the electromagnetic energy radiated outward by the antenna. The resonant frequency of the 5G antenna is slightly shifted, and the analysis shows that this is because the head is equivalent to a conductor, the frequency deviation of the PIFA antenna caused by a change in the shape of the floor below it. The isolation between the 5G antenna units is also reduced, also due to the reflection from the head or hand.Since both sides of the antenna are symmetrical, the radiation direction of one side of the antenna is shown in The proposed antenna has also been fabricated and verified in the laboratory. After completing the calibration, the scattering parameters of the antenna were measured in sequence, as shown in Due to the symmetry of the antenna on both sides, only one side of the antenna was tested, which includes the radiation patterns and gain of antennas 1 and 4. The radiation patterns of the antennas were measured and shown in The gain of the antenna is measured and shown in The performance comparison of the proposed eight-element mobile MIMO antenna with other mobile MIMO antennas is presented in 3 suits most of the smartphones. The standard parameters such as ECC and isolation still maintain an excellent level despite the burden of the wide band. The wide band also produces more gain with 5–6 dB, 3.5–6 dB, and 7–8 dB.The proposed antenna covers 2.0–2.6, 3.4–3.6, and 4.8–5.0 GHz, which is much wider than the antenna in This paper proposes an eight-element multimode mobile phone antenna consisting of two 4G antenna elements and six 5G antenna elements. Within the operating bandwidth of the antenna, the antenna elements are well matched, and the return loss of the antenna is greater than 10dB. The coupling between antenna elements is small, and the isolation between any two antenna elements is larger than 10 dB. By calculation, the envelope correlation coefficient between any two antenna elements is less than 0.1, indicating that the MIMO antenna has good diversity characteristics and small diversity gain. The simulation proves that the MIMO antenna is less affected by the human body when approaching the head and hand, and the radiation performance remains basically unchanged. The 4G antenna covers 4G mobile communication frequency bands such as B1, B38, B40, B41, and n41 frequency bands of 5G. The 5G antenna can work on the two frequencies of 3400–3600 MHz and 4800–5000 MHz, which can cover the n78 and n79 bands of 5G mobile communications, respectively, and are the two most mature frequency bands for sub-6 GHz applications.


In this paper, a novel ultra-wideband UWB antenna element with triple-band notches is proposed. The proposed UWB radiator element operates from 2.03 GHz up to 15.04 GHz with triple rejected bands at the WiMAX band (3.28–3.8 GHz), WLAN band (5.05–5.9 GHz), and X-band (7.78–8.51 GHz). In addition, the radiator supports the Bluetooth band (2.4–2.483 GHz). Three different techniques were utilized to obtain the triple-band notches. An alpha-shaped coupled line with a stub-loaded resonator (SLR) band stop filter was inserted along the main feeding line before the radiator to obtain a WiMAX band notch characteristic. Two identical U-shaped slots were etched on the proposed UWB radiator to achieve WLAN band notch characteristics with a very high degree of selectivity. Two identical metallic frames of an octagon-shaped electromagnetic band gap structure (EBG) were placed along the main feeding line to achieve the notch characteristic with X-band satellite communication with high sharpness edges. A novel UWB multiple-input multiple-output (MIMO) radiator is proposed. The proposed UWB-MIMO radiator was fabricated on FR-4 substrate material and measured. The isolation between every two adjacent ports was below −20 dB over the FCC-UWB spectrum and the Bluetooth band for the four MIMO antennas. The envelope correlation coefficient (ECC) between the proposed antennas in MIMO does not exceed 0.05. The diversity gains (DG) for all the radiators are greater than 9.98 dB. The communication link depending on ultra-wideband technology is a promising solution for numerous wireless networks, such as wireless body area networks (WBANs), Internet of Things (IoT) network systems, personal area networks (PAN), and remote sensing networks. The ultra-wideband communication network was selected because it uses a very high bandwidth radiator, which enables high-speed data transmission with low power consumption i.e., −44.2 dBm) . The UWB4.2 dBm .Since the UWB antenna uses an RF signal with low power and in the presence of some obstacles causing multipath fading, the multiple-input multiple-output (MIMO) network was introduced as a promising solution to solve this issue. Not only does the MIMO network system suppress multipath fading, but it also improves the network channel capacity . TherefoIn this paper, four ports of an UWB-MIMO structure were fabricated on a low-cost FR-4 substrate with relative permittivity of The article is arranged as follows. The design of a UWB antenna element is explained in h = 1.5 mm. The proposed UWB antenna element consists of three sections placed on the top layer of the dielectric substrate. The first one is a 50 C is the speed of light , one at the beginning of the WLAN band at a frequency of f = 4.94 GHz and the other one located at the end of the band at a frequency of f = 6.2 GHz. Thus, the WLAN band notch resembles a rectangular shape. This rectangular notch band improves the radiating characteristic of the antenna more than the conventional notch antenna .f = 7.29 GHz and f = 8.59 GHz, respectively. Adding the Bluetooth band to the UWB signal is very useful for establishing a communication channel between unlicensed bands for users/patients and diagnostic devices in biomedical applications.The final step in designing the proposed UWB antenna element with a triple band notch is to design a third band notch for X-band satellite communication that operates from 7.9 to 8.4 GHz. The X-band satellite communication band notch is required to be taken into account to overcome the interference between the obtained FCC-UWB signal and the X-band satellite signal. Electromagnetic band gap structure (EBG) technology is introduced to design a band stop filter to reject the licensed X-band satellite communication band over the aforementioned frequency range. A frame composed of an octagon-shaped EBG was proposed to achieve a band notch characteristic at X-band satellite communication in the UWB antenna, as shown in i is 1, 2, 3, and 4) at ports 1, 2, 3, and 4 of the UWB-MIMO antenna with the separate ground plane  configuration. It is shown that the FCC-UWB spectrum with triple band notches was obtained in addition to the Bluetooth band. On the other hand, i = 1, 2, 3, and 4) at ports 1, 2, 3, and 4 of the UWB-MIMO antenna with the common ground plane  configuration. It is noticed that the FCC-UWB spectrum with triple band notches was obtained but there is a mismatching characteristic at the Bluetooth band due to the coupling between the UWB antenna elements.Four proposed UWB antenna elements are perpendicularly placed to each other in order to design a MIMO structure, as shown in f = 2.44 GHz are shown in In order to overcome the problem mentioned above, a defective ground structure (DGS) band stop filter (BSF) was proposed and designed at the Bluetooth band . The two-port DGS-BSF was simulated in CST microwave studio, as shown in h = 1.5 mm. The proposed UWB-MIMO antenna was fabricated on FR-4 material with relative permittivity of i and port j, respectively, while i and port j.i  and port j . The suffixes i and j represent the port numbers. In the case of i = 1 and j = 2, the calculated i, respectively. j, respectively.ECC represents the envelope correlation coefficient between the radiated antennas in the MIMO configuration. There are two methods of calculating the ECC. One is obtained from the S-parameter characteristics using Equation , while tAnother important parameter in terms of diversity characteristics is the total active reflection coefficient (TARC). The total active reflection coefficient (TARC) parameter shows the active operating spectrum for the proposed MIMO radiator configuration. Equation  is used Finally, h = 1.5 mm. The UWB radiator element was proposed to operate in the FCC-UWB network. It has a bandwidth of 13.01 GHz extending from 2.03 to 15.04 GHz with triple band notches. The triple bands are the WiMAX band (3.28–3.8 GHz), WLAN band (5.05–5.9 GHz), and X-band (7.78–8.51 GHz). In addition to this, it supports the Bluetooth band (2.4–2.483 GHz). An alpha-shaped coupled line connected with a stub-loaded resonator (SLR) was proposed to achieve a band-stop characteristic at the WiMAX band. Two similar U-shaped slots etched on the radiator are utilized to obtain a band-stop characteristic WLAN band. Two unit cells of an octagon-shaped EBG structure are used to achieve a band-stop characteristic at X-band satellite communication. The three notch bands have excellent selectivity or sharpness at both the start and the end of each notch band. The UWB radiator is used in the MIMO configuration as an element. The ground planes of the four UWB radiators are connected together. Four DGS band-stop filters were placed between each ground plane and the center H-shaped ground connection to improve the matching characteristics at the Bluetooth band. In addition, high isolation characteristics were obtained at the operating band.Four ground-connected UWB-MIMO radiators were designed and fabricated on FR-4 dielectric substrate material with relative permittivity of


The simulated and measured results of the antenna show good agreement, making it well-suited for 5G mmWave communication applications.A novel compact-slotted four element multiple input multiple output (MIMO) planar monopole antenna is proposed for 5G mmWave N257/N258 and N262 band applications. The antenna, with dimensions of 12 mm × 11.6 mm × 0.508 mm ( Wireless communication networks are experiencing widespread usage, leading to an increased demand for significantly higher data rates, minimal latency, and efficient spectrum utilization in portable device applications. The advent of 5G (fifth generation) mobile communication technology offers several advantages over the current 4G (fourth generation) system, including higher transmission rates, improved spectrum efficiency, and reduced latency. Notably, 5G networks boast data rates that are 10 times higher than those of 4G networks, along with enhanced device connectivity and stability. The FCC has divided the 5G frequency spectrum into three bands: a low-band, sub-6 GHz band, and mmWave band. The mmWave frequency range, extending beyond 24 GHz, provides ample spectrum availability, enabling exceptional capacity, high throughput, and remarkably low latency. Consequently, various 5G mmWave antenna models have been proposed ,4,5. ForFor 2-element MIMO antenna systems, several approaches have been developed to enhance isolation ,18,19,20This research introduces a novel compact dual-band U-shaped MIMO design for 5G mmWave systems. The suggested design comprises four U-shaped radiating elements on top of a substrate with a slotted ground on the bottom. Each radiating element of the MIMO antenna is equipped with a rectangular strip and a pair of rectangular slots to enhance its impedance performance. The first operating band at 27.1 GHz is achieved using slotted U-shaped radiating elements, while the second operating band at 48.7 GHz is created by incorporating hexagonal slots into the ground plane. Additional isolation is provided by the orthogonal positioning of the antenna elements and narrow rectangular slots in the ground. The developed antenna exhibits consistent radiation patterns, high peak gain, increased radiation efficiency, negligible envelope correlation coefficient (ECC), acceptable total active reflection coefficient (TARC), minimal channel capacity losses (CCL), and low mean effective gain (MEG) at 27.1 GHz (N257/N258) and 48.7 GHz (N262) bands. The following subsections provide a detailed explanation of the proposed MIMO antenna.2, which has a thickness of 0.508 mm and a relative permittivity of 2.2. The antenna is fed via a 50-ohm microstrip line of sizes 1.035 × 0.3 mm2. The suggested antenna is made up of four U-shaped radiating elements (R1 to R4) on top of a dielectric material and slotted ground at the bottom. Each radiating element is formed by combining the sub-elements of dimensions 2.25 × 0.8 mm2, 1.565 × 0.8 mm2, and 4.59 × 1.145 mm2. The outer dimensions of the sub-elements of a patch are denoted by 3.395 mm, 4.59 mm, and 2.71 mm. Also, to enhance the MIMO antenna’s impedance performance , two rectangular slots (1.465 × 0.325 mm2 and 0.78 × 0.325 mm2) and a rectangular strip of 1.3 × 0.2 mm2 are added to each radiating patch. Using rectangular slots and a strip, first resonance was induced in the 27.1 GHz band, which covers from 25.9 GHz to 27.8 GHz as depicted in 2. Etching hexagonal slots on the ground plane results in the second operational band at 48.7 GHz from (47.1–49.9) GHz as shown in 2 are carved out of the ground plane to produce excellent isolation or minimal mutual coupling between the antenna elements. The rectangular slots are cut 0.1 mm from a corner of the substrate and slots are situated 5.85 mm and 5.65 mm from the substrate’s edges. The orthogonal arrangement of radiating elements and the right selection of distance between the radiating elements improve the isolation. The distance between the elements is 2.775 mm and 2.475 mm, as given in The surface current distribution parameter is one of the crucial visual parameters for MIMO antenna systems. It demonstrates how the current of one element affects another in the MIMO design. 2 (C × E mm2). Antenna #A operates at 27 GHz and 51.4 GHz which does not include the desired bands as from 2 and 0.685 × 0.8 mm2 from Antenna #A, Antenna #B is formed. Antenna #B only works at 27 GHz (N257/N258 band). To attain the second band at 48.7GHz (N262 band) in addition to the 27 GHz band, a hexagonal slot was cut from the ground plan. Moreover, to achieve impedance-matching properties at working bands, a couple of slots and a strip are used on the radiator. So, Antenna #C is adopted as the basic radiating element in the suggested MIMO antenna. The single antenna evolution stages’ current distribution on the surface is given in The single-element design and evolution process is described in In this subsection, the impact of feed width on antenna impedance performance is investigated. The effect of the ground slot on impedance performance is also examined in this section. The S11 responses of the different ground slots like a hexagon, octagon, and decagon are plotted in Two approaches are used in this work to provide excellent isolation between antenna ports which include an orthogonal arrangement of U-shaped radiating elements and the use of narrow rectangular ground slots. Here, the S-parameters S21, S31, and S41 are used to analyze the effect of narrow rectangular slots on the isolation performance. To evaluate the recommended MIMO antenna’s properties, a prototype was developed on a Rogers RT/duroid 5880 (tm) substrate and experimentally verified through Agilent N5224A VNA, as shown in The radiation performance of an antenna is one of the most crucial factors as it indicates the direction, strength, and nature of the radiated fields. −6, indicating substantial agreement in the simulated and measured values.This section analyzes the diversity performance of the suggested MIMO antenna using several metrics of performance such as the envelope correlation coefficient (ECC), diversity gain (DG), total active reflection coefficient (TARC), channel capacity loss (CCL), and mean effective gain (MEG). The MIMO antenna diversity is analyzed using the ECC ,35,36,37The diversity gain is an indicator of how well antenna diversity methods perform ,35,36,37Individual MIMO antenna S-parameters will not provide an exact analysis. The total active reflection coefficient (TARC) can be utilized to estimate the performance of MIMO systems. TARC takes into account self and mutual impedance variations . The TARThe assessment of the channel capacity loss (CCL) is also necessary for the design of MIMO antennae. The formulas in Equations (4)–(6) can be used to determine this parameter as a function of the S-parameters . The CCLThe recommended MIMO antenna performance has been compared to other antennae that have been previously described in For 5G mmWave N257/N258 and N262 band applications, a miniaturized dual-band slotted four element MIMO planar monopole antenna is proposed. The antenna design consists of four U-shaped radiating elements on top of the dielectric material and a slotted ground on the bottom. To enhance the impedance performance of the MIMO antenna, a rectangular strip and a pair of rectangular slots are added to each radiating element. The first operating band at 27.1 GHz, ranging from 25.9 GHz to 27.8 GHz, is achieved using slotted U-shaped radiating elements. The second operating band at 48.7 GHz, ranging from 47.1 GHz to 49.9 GHz, is obtained by etching hexagonal slots on the ground plane. The orthogonal positioning of the radiating elements and the presence of narrow rectangular slots on the ground provide isolation of more than 27 dB. The designed antenna operates at 27 GHz (N257/N258) and 48.7 GHz (N262) bands, exhibiting stable radiation patterns, high peak gain, increased radiation efficiency, very low envelope correlation coefficient (ECC), acceptable total active reflection coefficient (TARC), negligible channel capacity losses (CCL), and low mean effective gain (MEG). The proposed antenna is modeled, manufactured, and its results are measured. The simulation and test findings demonstrate good agreement, indicating that the proposed antenna is a suitable choice for 5G mmWave N257/N258 and N262 band applications.