Flexible Ultra-wideband Antenna Research Articles

A compact tri-notched flexible UWB antenna based on an inkjet-printable and plasma-activated silver nano ink

The rapid development of ultrawideband (UWB) communication systems has resulted in increasing performance requirements for the antenna system. In addition to a wide bandwidth, fast propagation rates and compact dimensions, flexibility, wearability or portability are also desirable for UWB antennas, as are excellent notch characteristics. Although progress has been made in the development of flexible/wearable antennas desired notch properties are still rather limited. Moreover, most presently available flexible UWB antennas are fabricated using environmentally not attractive subtractive etching-based processes. The usage of facile additive sustainably inkjet printing processes also utilizing low temperature plasma-activated conductive inks is rarely reported. In addition, the currently used tri-notched flexible UWB antenna designs have a relatively large footprint, which poses difficulties when integrated into miniaturized and compact communication devices. In this work, a silver nano ink is used to fabricate the antenna via inkjet printing and an efficient plasma sintering procedure. For the targeted UWB applications miniaturized tri-notched flexible antenna is realized on a flexible polyethylene terephthalate (PET) substrate with a compact size of 17.6 mm × 16 mm × 0.12 mm. The antenna operates in the UWB frequency band (2.9–10.61 GHz), and can shield interferences from WiMAX (3.3–3.6 GHz), WLAN (5.150–5.825 GHz) and X-uplink (7.9–8.4 GHz) bands, as well as exhibits a certain of bendability. Three nested "C" slots of different sizes were adopted to achieve notch features. The simulation and test results demonstrate that the proposed antenna can generate signal radiation in the desired UWB frequency band while retaining the desired notch properties and having acceptable SAR values on-body, making it a viable candidate for usage in flexible or wearable communication transmission devices. The research provides a facile and highly efficient method for fabricating flexible/wearable UWB antennas, that is, the effective combination of inkjet printing processing, flexible substrates, low temperature-activated conductive ink and antenna structure design.

Ultrathin and Flexible Ultrawideband Antenna Array Based on Integrated Impedance Matching Line

Ultrathin and Flexible Ultrawideband Antenna Array Based on Integrated Impedance Matching Line

A flower bud-shaped flexible UWB antenna for healthcare applications

Remote surveillance of the elderly and others with health difficulties is becoming increasingly important in these epidemic days. To address these issues, low-cost, lightweight, and portable wearable devices are in huge demand. This paper realizes the design and analysis of a flexible ultra-wideband (UWB) antenna for healthcare applications. The proposed hexagonal microstrip antenna encompasses two cuts on the top left and right side of the hexagon which looks like a flower bud. The antenna is fabricated using a flexible foam substrate with a dielectric constant of 1.07 and has a dimension of 38 times 30 times 1.7,{text{mm}}^{3}. With a unique patch shape and corner cut in the partial ground, the present design strives to optimize the antenna structure to accommodate UWB (3.1 to 10.6 GHz) operating spectrum from 2.6 to 11.3 GHz. The proposed antenna has achieved an FBW of 125.17% with a total gain of 5.24 dB. The antenna is also evaluated on the line of bending and SAR over a tissue of 1 g and 10 g. The antenna operated admirably, with an average SAR value below the safety limits of 1.6 W/kg and 2 W/kg for the tissues, respectively.

MULTIBAND FLEXIBLE ULTRA-WIDEBAND ANTENNA FOR WEARABLE ELECTRONICS AND BIOMEDICAL APPLICATIONS

This article proposes a flexible ultra-wideband (UWB) antenna for wearable electronics and biomedical applications. The antenna presented for this work is fabricated on a Kapton polyimide (PI) substrate, and the operating frequency ranges from 2.4 GHz to 7.1 GHz. The footprint of the proposed antenna is 35 × 45 mm with an elliptical radiating element fed by coplanar waveguide (CPW), which achieves improved impedance matching characteristics. The choice of substrate, design constraints, fabrication process, and bending test of the proposed flexible UWB antenna are explained in detail in this paper. A comparative study on the choice of substrate is performed and the Kapton PI is chosen as the substrate material, which makes the antenna less susceptible to degradation in antenna performance that arises due to bending effects. The measurement and simulated results of the fabricated antenna show a good degree of agreement. The return loss performance of the proposed antenna is greater than -10 dB in all the operating bands with improved gain and directivity. The flexible nature with multiple frequency bands of operation and good bending performance makes the proposed antenna appropriate for wearable electronic and biomedical applications.

Flexible UWB and MIMO Antennas for Wireless Body Area Network: A Review

In recent years, there has been a surge of interest in the field of wireless communication for designing a monitoring system to observe the activity of the human body remotely. With the use of wireless body area networks (WBAN), chronic health and physical activity may be tracked without interfering with routine lifestyle. This crucial real-time data transmission requires low power, high speed, and broader bandwidth communication. Ultrawideband (UWB) technology has been explored for short-range and high-speed applications to cater to these demands over the last decades. The antenna is a crucial component of the WBAN system, which lowers the overall system's performance. The human body's morphology necessitates a flexible antenna. In this article, we comprehensively survey the relevant flexible materials and their qualities utilized to develop the flexible antenna. Further, we retrospectively investigate the design issues and the strategies employed in designing the flexible UWB antenna, such as incorporating the modified ground layer, including the parasitic elements, coplanar waveguide, metamaterial loading, etc. To improve isolation and channel capacity in WBAN applications, the most recent decoupling structures proven in UWB MIMO technology are presented.

SAR Evaluation of Flexible UWB Antenna for Wearable Applications

This manuscript appearance a compact and Ultra-Wideband (UWB) antenna for wearable applications. The proposed coplanar waveguide (CPW) feed circular configuration patch antenna is simulated on two different dielectric materials one flexible polyamide based Cordura fabric and other is FR-4, with small footprint of size 36 × 46 mm2. The antenna works in complete UWB band from 3.1 to 10.6 GHz. The performance of the antenna was examined in free space and three-layer human body phantom. This research work also presents the flexibility analysis of structure for both substrates. These examinations exhibited that proposed UWB antenna is an appropriate contender for wireless body area network (WBAN) operation.

Design and analysis of a CPW ‐fed flexible ultrawideband antenna for microwave imaging of breast cancer

This article presents a novel CPW fed ultrawideband (UWB) antenna for detection of unwanted tumor cells in the human breast. Here, a compact and miniaturized UWB antenna employed with dodecagonal edges is proposed for broadening the bandwidth from 2.26 to 13.71 GHz (measured fractional bandwidth of about 143.39%). The antenna is designed on a durable RT 5880 substrate having 0.254 mm thickness, efficiency of 85% and gain of 3.84 dBi. For its flexibility characterization, the prototype of the fabricated antenna is analyzed in both the flat and bending configurations. The simulated testing is carried out by permitting the antenna to emit radiation in conjunction to the human breast phantom to obtain desired antenna characteristics for the microwave imaging (MI) applications. The changes in reflection coefficient with the variation of dielectric content of the breast phantom structure are analyzed. The suggested antenna for MI technique is apt for human exposure because the antenna bids the highest SAR value of 0.932 W/Kg at 10.6 GHz. Moreover, the proposed antenna is flexible, compact and low-profile with low SAR values that can be useful for breast cancer detection.

Early detection of acute coronary syndrome through prothrombin time measurement using flexible UWB antenna for cardiac patient

Acute coronary syndrome (ACS) is the disease occurs due to clot formation in heart arteries. The prothrombin time (PT) of the blood measures various health disorders such as liver dysfunction, cardiac function, internal bleeding and internal blood clots. The PT measurement through optical and mechanical coagulation analyzers is influenced by plasma turbidity, reagent sensitivity and vitamin K levels. In this paper a novel method for early detection of ACS through PT measurement using flexible ultra-wide band (UWB) antenna is proposed. This study is carried on 200 persons with and without ACS. In the proposed method the electromagnetic radiations absorbed from the plasma sample using flexible ultra-wide band antenna is processed further to determine the prothrombin time. The plasma concentration is proportional to electromagnetic energy density and based on the voltage clotting duration is acquired. The clotting frequency ranges of human blood varies from 2 GHz to 3 GHz and voltage from 0.55 mV to 0.85 mV in the observed electromagnetic radiation. The clot concentration is measured from the observed electromagnetic emitted voltage which is converted into frequency during clotting. The prothrombin time is measured from the acquired clotting concentrated voltage through regression modelling and validated through laboratory standards. The proposed UWB antenna based prothrombin time measurement achieves 96.48% accuracy in detecting ACS at the early stage The variations in PT values, need for reagents, vitamin-K impacts, and plasma turbidity impacts were eradicated in the proposed method and ACS is detected early from the measured PT values.

Design and comparative analysis of compact flexible UWB antenna using different substrate materials for WBAN applications

In the present scenario, smart devices are using flexible wearable wireless technologies to enable interaction among people and their surrounding equipments. Due to the commercialization of these flexible electronic devices and systems, these systems require the integration of flexible antennas. The compactness and flexibility of the antenna are the major objectives of the current research. This paper highlights the comparative study of a small-sized swastika-shaped slotted patch ultra-wide-band (UWB) antenna. The designed microstrip patch antenna is simulated using Rogers RT 5880 as a substrate mounted on the partial ground structure. A rectangular substrate with a size of 24.56 × 22.48 mm × 1.575 mm is placed between the partial ground and patch. The dimensions of the radiating patch are 13 mm × 10.5 mm × 0.035 mm. The resonant frequencies of the designed antenna are 4.43 GHz and 8.84 GHz and have a large fractional bandwidth of 110% in the range of 3.1 to 10.7 GHz. The maximum observed gain and directivity of the proposed antenna are 5.9 dB and 6.8 dBi at 4.43 GHz. The simulation of the presented antenna design is performed in CST Microwave Studio 2018. The proposed antenna performance metrics are comparatively analyzed using different substrate materials like Rogers RT 5880, Jeans, and rubber substrates. The developed dual-band antenna can be useful for WBAN communication applications in the UWB band.

A Conformal Ultrawideband Antenna With Monopole-Like Radiation Patterns

A simple conformal ultrawideband (UWB) antenna with monopole-like radiation patterns is proposed in this communication. To achieve the wide bandwidth, two rings are arranged concentrically around the main annular-ring circular patch antenna, in which two rectangular slots are added. The antenna has monopole-like radiation patterns generated by combining four propagation modes of TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">01</sub> , TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">02</sub> , TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">03</sub> , and TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">04</sub> throughout the operating bands. To enhance the flexibility and robustness, the proposed antenna is fabricated using conductive fabric embedded into polydimethylsiloxane (PDMS) polymer. To our knowledge, this is the first flexible UWB antenna with monopole-like radiation patterns reported in the open literature. The measured results show that the antenna achieves a 10 dB return loss bandwidth from 2.85 to 8.6 GHz. Monopole-like radiation patterns are maintained throughout the frequency band, agreeing well with simulated results. This has been validated through the measured mean realized gain (MRG) pattern from 2.85 to 8.6 GHz. The fabricated antenna was bent and tested at various curvatures to verify its conformability. To evaluate suitability for UWB communications, the system-fidelity factors of the antenna are investigated using full-wave analysis in CST Microwave Studio, in both flat and bent conditions, validating its potential for UWB pulse transmission.

Design and performance analysis of a conformal CPW fed wideband antenna with Mu-Negative metamaterial for wearable applications

AbstractIn this paper, a flexible CPW fed ultrawide band (UWB) antenna with mu-negative (MNG) metamaterial is designed, fabricated, and tested for wearable applications. Initially, a UWB antenna of size 50 mm × 43 mm is fabricated on two different substrates, viz. flexible FR4 and semi-flexible Rogers RT/duroid 5880. A metamaterial structure fabricated on flexible FR4 shows a magnetic resonance from 7.2 GHz to 9.2 GHz with maximum stop band attenuation (−49 dB) and high MNG value (−2121.6) at 7.87 GHz. Then a (3 × 3) array of designed MNG metasurface is used as ground plane with flexible UWB antenna, which improves its overall gain and radiation pattern. The performance of the flexible antenna with/without metamaterial at various distances from flat and cylindrical three-layered human phantom of skin, fat, and muscle is studied. Further, the bending characteristics at different angles and performance over thin metallic sheet is also evaluated. Additionally, the peak specific absorption rate value averaged over 1 g of tissue at three chosen frequencies from UWB range (3, 5, 10 GHz) with/without metamaterial using 0.3 and 0.1 W of input power is also analyzed. The simulated and measured results are in good agreement which confirms that the designed antenna is a good candidate for wearable applications.

A CPW-fed flexible UWB antenna for IoT applications

In order to keep pace with the growing research and development on flexible and reconfigurable electronics, this research presents an inkjet printed ultra-wideband (UWB) flexible antenna on photo paper. The antenna pattern comprises a circular patch with the double stepped symmetric ground plane and is fed by a coplanar waveguide (CPW) technique on one-sided photo paper. The system is designed, simulated, fabricated, and tested experimentally. It operates over 3.2–30 GHz (161% fractional bandwidth, FBW) range with a return loss of − 10 dB or less and a voltage standing wave ratio (VSWR) < 2. The proposed monopole antenna is of dimensions 33.1 mm × 32.7 mm × 0.254 mm with an electrical size of 0.35 λ × 0.35 λ at 3.2 GHz frequency. This design exhibits nearly omnidirectional radiation pattern over the entire impedance bandwidth. An average gain of 4.87 and a radiation efficiency of 86.61% was observed. The miniature size, higher operating range, relatively constant radiation pattern along with higher acceptable peak gain of the antenna on a paper substrate lend itself to wearable and Internet of Things (IoT) applications.

Flexible ultra-wideband antenna incorporated with metamaterial structures: multiple notches for chipless RFID application

A coplanar waveguide (CPW) ultra-wideband (UWB) antenna incorporated with metamaterial—split ring resonator structure—that operates from 3.0 to 12.0 GHz is proposed for chipless RFID tag. The 30 mm × 40 mm flexible chipless RFID tag is designed on the fleece substrate (er = 1.35, thickness = 1 mm and tan \( \delta \) = 0.025). A six-slotted modified complementary split ring resonator (MCSRR) is introduced into the ultra-wideband antenna to produce multiple band notches at 3.0, 4.0, 5.0, 6.0 and 7.0 GHz. The frequency shifting technique is introduced for designing a high-capacity chipless RFID tag with compact size. Each MCSRR is able to code in four different allocations (00, 01, 10 and 11). To achieve encoding of 10-bits data (10,234 number), six MCSRRs are proposed with three-slotted MCSRR in the radiator and three-slotted MCSRR in the ground plane.

A Compact, Highly Efficient and Flexible Polymer Ultra-Wideband Antenna

A compact, highly efficient and flexible ultra-wideband antenna operating from 3 to 20 GHz is proposed in this letter. The antenna is completely made from polymer comprising a patterned conductive polymer (PEDOT) thin film attached to a transparent sticky tape substrate. The overall dimension is less than a quarter-wavelength at the lowest frequency of operation and the device reaches a radiation efficiency of over 85% averaged throughout the frequency band. The antenna performs well under various bending conditions as demonstrated by measurements. The realized antenna offers great mechanical flexibility and robustness which indicates its promising potential for possible seamless integration in flexible electronics.

Design and Fabrication of Compact Inkjet Printed Antennas for Integration Within Flexible and Wearable Electronics

The demand for flexible and wearable wireless systems is increasing exponentially in today's information-oriented society. These systems are extremely beneficial and applied in a wide spectrum of fields, such as personal communication, medicine, military, firefighting, entertainment, aeronautics, and radio frequency identification. In this paper, the design constraints, fabrication process, flexibility tests, and measurement of flexible and wearable antennas are discussed in detail. Furthermore, the design, fabrication, and testing of a compact flexible ultrawideband antenna are presented. The proposed design has the merits of light weight, ultralow profile (50.8 μm), wideband width, mechanical robustness, compactness, and high efficiency. The antenna is also tested against bending effects to characterize its performance in a realistic setup since it is expected to be conformed on curved surfaces and/or flexed during operation.