A 2.45-GHz rectifying antenna (rectenna) using a compact dual circularly polarized (DCP) patch antenna with an RF-dc power conversion part is presented. The DCP antenna is coupled to a microstrip line by an aperture in the ground plane and includes a bandpass filter for harmonic rejections. It exhibits a measured bandwidth of 2100 MHz (10 dB return loss) and a 705-MHz CP bandwidth (3 dB axial ratio). The maximum efficiency and dc voltage are respectively equal to 63% and 2.82 V over a resistive load of 1600 Ω for a power density of 0.525 mW/cm 2 .
A millimeter-wave (mmWave) textile antenna operating at 26 GHz band for 5G cellular networks is proposed in this paper. The electromagnetic characterization of the textile fabric used as substrate at the operating frequency was measured. The textile antenna was integrated with an electromagnetic bandgap (EBG) structure and placed on a polyester fabric substrate around the antenna. Results showed that the proposed EBG significantly improved the performance of the antenna. The gain and energy efficiency at 26 GHz were 8.65 dBi and 61%, respectively (an increase of 2.52 dB and 7% compared to a conventional antenna), and the specific absorption rate (SAR) was reduced by more than 69.9%. Good impedance matching of the fabricated antenna at the desired frequency was observed when it was bent and worn on the human body. The structure is simple, compact, and easy to manufacture. It may well be suitable for integration into applied clothing in various fields, especially for future IoT applications.
23 February 2018 in IET Microwaves, Antennas & Propagation
This study focuses on the design, simulation, and fabrication of a coplanar waveguide miniaturised wearable antenna that is fully implemented in textile materials and operable at 2.45/5.8 GHz for wireless local area network applications. This antenna is assumed to be placed near the human body, so that it needs to be miniaturised with excellent performances. To increase the performance of the short‐distance textile antenna and to control the specific absorption rate, an artificial magnetic conductor (AMC) is preferred as a reflector plane. The volume of the proposed antenna with AMC is 75 × 50 × 6 mm 3 , the simulation and measurement results are in good agreement and show that the antenna performances perform better results in comparison with the one reported so far in the literature while having a smaller volume. AMC significantly improves the performance of the antenna. The gains of the antenna are 8.2 and 9.95 dBi at 2.45 and 5.8 GHz, respectively (an increase of 3 dB compared with an antenna without AMC).
24 April 2018 in Microwave and Optical Technology Letters
This paper presents a low-profile, wearable textile antenna, designed for Wireless Body Area Network (WBAN) applications operating in the 5.8GHz band for Industrial, Scientific, and Medical (ISM) applications. An Artificial Magnetic Conductor (AMC) structure was used to improve antenna performance and protect the human body from back-radiation. The antenna with the integrated AMC achieved a measured gain of 8.92dBi, an efficiency of 80%, a wide impedance bandwidth of 1.4GHz (24.1%), and SAR values of 0.00103 and 0.00034W/Kg for 10g and 1g tissues respectively. The proposed antenna was studied in a worn-on-body scenario using a multilayer numerical model of the human body. The influence of the thickness of each tissue layer of the human body was investigated. The results showed that the antenna maintained its performance, a stable gain was obtained, and the SAR values were also below the IEEE guidelines that guarantee the safety of the wearer.
This paper deals with miniaturization of wearable electro-textile antennas by the use of Minkowski fractal geometries. Two electro-textile materials namely Flectron and Zelt are considered for the design of flexible microstrip antennas. In both cases, polyester fabric material has been employed as dielectric medium. In the basic design both the antennas are designed for WLAN applications. The Flectron antenna provides a gain of 6.54 dB with an impedance bandwidth of 132 MHz whereas, the Zelt antenna offers a gain of 7.4 dB and an impedance bandwidth of 104 MHz. By applying Minkowski fractal geometry to the antennas, miniaturization is achieved. In its first iteration, antenna designs are optimized and tuned to WiBro band and in the second iteration, antennas are further miniaturized in order to make them suitable for GSM 1900 applications. In these two bands, the gain and efficiency of both Flectron and Zelt antennas conform to their respective wireless standards. The simulation studies reveal that Zelt antenna yields better results compared to Flectron antenna.