12. E. Chiprout and M.S. Nakhla, Asymptotic waveform evaluation and moment matching for interconnect analysis, Kluwer Academic Pub- lishers, Boston, MA, 1994, 197 pp. 13. Y. Saad and M.H. Schultz, GMRES: A generalized minimal residual algorithm for solving nonsymmetric linear systems, SIAM J Sci Stat Comput 7 (1986), 856–869. V C 2014 Wiley Periodicals, Inc. EMBROIDERED WEARABLE TEXTILE ANTENNA ON BENDING AND WET PERFORMANCES FOR UWB RECEPTION M. S. Shakhirul, M. Jusoh, A. Sahadah, C. M. Nor, and Hasliza A. Rahim Embedded, Network and Advanced Computing (ENAC), School of Computer and Communication Engineering, Universiti Malaysia Perlis (UniMAP), Kampus Pauh Putra, 02600, Arau, Perlis, Malaysia; Corresponding author: muzammiljusoh11@gmail.com Received 3 February 2014 ABSTRACT: This research proposed an integration of the telecommu- nication system within garment and wearable product known as textile antenna. Such antenna performances on bending and wet conditions are discussed in the manuscript. This embroidered antenna provides a wide operating band satisfying an ultrawideband application of 3.1–10.6 GHz at 10 dB return loss. The proposed antenna is developed from a simple circular with T-slot structure and a partial ground plane. The fabricated textile antenna was made from both conductive and nonconductive wear- able materials. The simulated and measured bend angles of 20  , 30  , 40  , 50  , 60  , 70  , and 80  is analyzed in terms of reflection coefficient via computer simulation technology software and programmable network analyzer, respectively. Moreover, the proposed embroidered antenna performance in wet conditions are investigated in four states of antenna inside water, antenna immediately wet, antenna approximately dry, and antenna completely dry. Simulated and measured results of reflection coefficient, surface current distribution, and gain are presented to vali- date the usefulness of the presented design. V C 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:2158–2163, 2014; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.28527 Key words: embroidered antenna; textile antenna; bending; wet performances 1. INTRODUCTION Recently, wearable textile antenna has gained huge attention among the researchers and industry players with respect to the fast growing and wide range of wireless body centric system such as in sports, security, healthcare, and military applications [1]. The concept of integrating the communication system into the garment has improved the quality of the human being life by providing the wearable tracking- and monitoring-based appli- cation. In such system, wearable antenna plays an important role in realizing and ensuring the reliability of the wireless commu- nication link between body-worn electronic and the surrounding environment. These textile antennas have advantages of light weight, washable, high flexibility, soft, and comfortable to the wearer [2,3]. To the authors knowledge so far, the wearable textile antenna can be categorized into three; embroidery, patch, and printed and painted [4–6]. Research in [4] discussed a wearable textile antenna with multiple resonance frequency for FM reception using conductive embroidery of metal composite embroidery yarn on a polyester woven substrate. A square ring patch with a polygon-shaped slot with wide band performance is needed in bending conditions when a frequency shift is probable [5]. Such patch antenna focusing on Cordura substrate textile, which ful- filled the mechanical qualification requirements. An inkjet- printed textile antenna is studied in [6] where it proposed an interface coated layer, which bond to a standard polyester cotton fabric to overcome surface roughness. However, this manuscript is focusing on embroidery textile antenna for ultrawideband (UWB) application. The commercial use of UWB between operating frequency of 3.1–10.6 GHz has been approved by the Federal Communica- tions Commission (FCC) in 2002 [7]. However, the UWB sys- tem must possess a very low-power spectral density with the ability to coexist with the narrowband system as depicted in Figure 1. Therefore, with the lower transmission power to the receiver end has contributed to the higher life battery. Owing to the other benefits of UWB technology, such as multipath robust- ness and license exemption [8], the high impedance bandwidth (BW) of 7.5 GHz reduces the wearable antenna device. In this letter, the wearable textile antenna operating at UWB band has a substrate dimension of 60 3 63 mm 2 with a partial ground plane. The proposed antenna consists of a circular- shaped radiator with a feed line structure. Analysis of the pres- ence and absence of the T-slot is investigated in simulation and measurement mode toward the reflection coefficient result. Ulti- mately, the analysis shows that the radiator with T-slot has bet- ter impedance BW that meet UWB requirement with high efficiency of more than 88%. Moreover, further investigation on the bending angles at particular 20  , 30  , 40  , 50  , 60  , 70  , and 80  are carried out. The result shows that the 20  , 60  , and 70  angles give better impedance band as compared to the others. However, the main challenge arises during fabrication process. Besides, the proposed embroidery antenna performances on wet condition has been studied in four states of inside water, imme- diately wet, approximately dry, and completely dry. All design and simulation is carried out using computer simulation technol- ogy (CST) simulation software. While all fabrication and mea- surement are performed in the Amrellab of Universiti Malaysia Perlis (UniMAP). The remainder of this article is organized as follows. In Sec- tion 2, the development of the wearable antenna design with and without T-slot is discussed. Besides, the fabricated material used also presented in this section. The analysis of the seven bending angles performance toward reflection coefficient is dis- cussed. Moreover, the simulated and measured antenna perform- ances in few wet conditions are converse in Section 3. Finally, conclusion is drawn in Section 4. 2. ANTENNA DESIGN AND CONFIGURATION Instead of using rigid circuit boards, cotton fabric is used as substrate, conductive fabric “Nora dell” as a ground plane and Figure 1 Operating frequency of UWB and narrowband system [7]. [Color figure can be viewed in the online issue, which is available at wileyonlinelibrary.com] 2158 MICROWAVE AND OPTICAL TECHNOLOGY LETTERS / Vol. 56, No. 9, September 2014 DOI 10.1002/mop