Imen Sfar

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.

The use of the wireless electronics in clothing is essential in our days in order to maintain user safety, rescue work and military personal communication. It can also be dedicated to medical and sports space applications. For this reason, this study is devoted to the design of a textile antenna operating in the WLAN bands (2.4-2.484 GHz) & (5.15-5.825 GHz). This antenna, fed by a coplanar waveguide (CPW), is intended to be integrated and carried in a person's clothing. For that purpose, we used metamaterial structures like artificial magnetic conductor (AMC) to increase the performance of the antenna in terms of radiation and reduce the coupling with the human body.

Currently, antennas integrated in clothing are particularly interesting because they can employ conductive elements which are already in garments. Therefore, this study is spent on the design of a dual-band textile antenna for WLAN applications. Its dual-band is fed by a coplanar waveguide (CPW) configuration. The proposed antenna structure is produced from jute fabric and operates in the 2 to 2.57 GHz band & 4.26 GHz to 6.GHz band, at bands of 2.48 and 5.76 GHz, respectively, which cover the 2.4/ 5.2/ 5.8 GHz WLAN operating bands. The antenna looks like a double G form. The aim is creating two different paths for the current traversing the strips and thus creating two resonant modes depending on the electrical lengths of the strips. CST Microwave Studio Software was used to design and simulate the structure. Moreover, performances in terms of radiation pattern and gain are presented and discussed.

This paper focuses on the design of a planar 4×4 butler matrix functioning at 2.45 GHz band frequency. The purpose is to exploit this matrix as a beam forming network generating orthogonal beams oriented towards various directions. For that, we have implemented a simple microstrip structure with single layer. We have also integrated some microwave devices, namely phase-shifters, 3 dB couplers and cross-couplers.

This paper presents results of direction of arrival (DOA) estimation using multiple signal classification (MUSIC), Root-MUSIC, and estimation of signal parameters via rotational invariance technique algorithms. As is well known, these algorithms are mainly based on the specific properties of the signal covariance matrix as well as the decomposition of the observation space into two subspaces, one for the signal and the other for the noise. Here, we are particularly interested in the quality of sources localization considering only the case of uncorrelated radio frequency signals impinging on an antenna array. A measurement system consisting of a linear array antenna and a five-port network applicable to a demodulator such as a receiver is used for the DOA estimation process. Co-simulations performed with the Advanced Device System and Matlab yielded interesting results not only on their performance but also on their limitation.

In this paper, we present the design of ultra wideband (UWB) planar Five-Port Reflectometer using the elliptic coupler which has the advantage to offer a wide bandwidth compared to the hybrid one. The elliptic coupler and the five-port circuit were designed and simulated in the 1.5 to 3.5 GHz band using ADS software of Agilent. An analytical calculus and simulation results of a five-port circuit using elliptic coupler demonstrate limitations of this structure.