RESEARCH ARTICLE Even and odd mode CPW-fed pattern diversity antenna for body centric communication systems A. M. Faiz 1 | N. Gogosh 2 | S. A. Khan 2 | M. Farhan Shafique 3 1 Laboratoire ESYCOM, University of Paris Est, Champs-sur-Marne, France 2 Department of Electrical Engineering, COMSATS Institute of Information Technology, Islamabad, Pakistan 3 Center for Advanced Studies in Telecommunication, COMSATS Institute of Information Technology, Islamabad, Pakistan Correspondence M. Farhan Shafique, Academic Block 1, CAST, COMSATS Institute of Information Technology, park road, Islamabad, 45550, Pakistan Email: farhan.shafique@comsats.edu.pk Abstract A patterns diversity slot antenna loaded with a dielectric reso- nator is presented for on-body communication systems in 2.45 GHz band. The diversity is achieved by launching even and odd modes on coplanar feed lines resulting in end-fire and broadside radiation pattern respectively. Loading of dielectric resonator enhances impedance bandwidth and improves isolation between broadside and end-fire patterns. A common impedance bandwidth of 4% is obtained along with ports isolation of 22 dB. Diversity gain is calculated for three unique on-body channels and the maximum diversity gain of 8.5 dB is achieved for nonline-of-sight on body channel. Large diversity gain and planar geometry makes this antenna suitable for various on-body communication applications. KEYWORDS dielectric resonator, diversity gain, even and odd modes, on body channels, wireless LAN 1 | INTRODUCTION Diversity gain (DG) antennas are meticulously investigated in order to develop a highly efficient and fault tolerant designs for on-body communication systems. The perfor- mance of such systems primarily relies upon the advantages extended by the diversity gain capabilities. The diversity can be of any type among space, polarization, or pattern diver- sity. Space diversity is one of the most commonly employed diversity technique; however, it requires larger antenna foot- print, and thus, it is more suitable for base station applica- tions. On the other hand, for mobile terminals and for body area networks (BANs), pattern diversity antennas are better alternative where co-located antennas yield different radia- tion patterns to introduce the desired diversity gain 1 . A pat- tern diversity antenna generates uncorrelated and directional radiation beams. The radiation pattern thus provides diver- sity gain in order to achieve better signal-to-noise ratio 2 . For wearable sensor applications like real-time patient monitoring systems, these diversity antennas can play vital role by ensuring high signal-to-noise ratio. These antennas, along with related sensing elements, are installed on differ- ent sections of a human body resulting in creation of differ- ent on-body channels between transmitting and receiving antennas 3 . In a recent work, a pattern diversity antennas for BAN has been proposed which is realized by stacking two patch antennas. The two patches are excited to generate TM11 and TM01 modes to achieve the pattern diversity which is computed through selection combining technique 4 . A miniaturized chip antenna has been reported in 5 that is used to evaluate off-body channel parameters like link bud- get, power delay, and channel capacity. The chip antennas offer pattern diversity and were deployed on a human body, whereas the receiving antenna was deployed in a rich scatter- ing laboratory environment. In another work, a combination of disk-loaded parasitic monopole antenna elements have been used to determine the on-body channel losses. The cen- tral antenna element is fed with the signal and the surround- ing four elements are passive which act as directors to switch the beam directions. The measurements of belt-to- chest and belt-to-wrist channels have been done at 2.45 GHz frequency. It is shown that the performance has been improved on average by 3.1 dB as compared to that of a standard monopole antenna 6 . A number of ultra wideband diversity antennas have also been reported like in 7 two UWB antennas have been pro- posed for body centric communications, One of them is wide slot antenna that operates from 6.8-9.1 GHz, whereas the other one is a reduced size wide slot antenna which works in 6.3-11 GHz frequency range. Implantable antennas like epsilon-negative zeroth-order resonance antenna for medical Received: 13 March 2018 DOI: 10.1002/mop.31481 Microw Opt Technol Lett. 2018;1–5. wileyonlinelibrary.com/journal/mop © 2018 Wiley Periodicals, Inc. 1