Bodycentric wireless communication BodyCentric Antennas Fundamental Principles Zbynk

Body-centric wireless communication Body-Centric Antennas: Fundamental Principles Zbyněk Raida raida@vut. cz Vytvořeno za podpory projektu OP VVV Moderní a otevřené studium techniky CZ. 02. 2. 69/0. 0/16_015/0002430

Recap § Can you compare properties of a wired communication and a wireless one in biomedical applications? § Can the human body play the role of a ground plane? § What effects influence attenuation of the on-body wave? § What does the Norton wave mean? raida@vut. cz 2

Contents § On-body communication -- Maximum radiation along human body -- Horizontally polarized wave § Off-body communication -- Maximum radiation perpendicular to human body -- Circular polarization advantageous § Implementation -- Planar antennas on a skin preferred raida@vut. cz 3

On-body propagation § Vertical versus horizontal polarization § 5. 8 GHz versus 60 GHz ISM band raida@vut. cz 4

Vertical polarization: monopole f 1 = 5. 4 GHz, f 2 = 5. 8 GHz f 3 = 6. 5 GHz raida@vut. cz 5

Vertical polarization: monopole raida@vut. cz 6

Vertical polarization: slot raida@vut. cz 7

Vertical polarization: slot dipole Notches: for the same current length, the reduced area is needed raida@vut. cz 8

Slot dipole: quasi-fractal iterations Iteration: zero Optimum ratio: 1. 00 first : 0. 58 raida@vut. cz second : 0. 43 9

Slot dipole: free-space 5. 5 GHz y x xz plane G = 4. 1 d. Bi@5. 5 GHz BW = 39. 64% raida@vut. cz 10

Slot dipole: free-space 5. 5 GHz PÍTRA, K. ; RAIDA, Z. Miniaturized antenna for body centric communication, European Conference on Antennas and Propagation, Eu. CAP 2013. Gothenborg, Sweden: 2013. y x yz plane xz plane raida@vut. cz 11

Slot dipole: free-space 5. 5 GHz PÍTRA, K. ; RAIDA, Z. Miniaturized antenna for body centric communication, European Conference on Antennas and Propagation, Eu. CAP 2013. Gothenborg, Sweden: 2013. y x Iteration Dimensions [mm] Bandwidth [mm] VSWR in band 0 60 × 35 25. 7 1. 35 1 30 × 25 39. 6 1. 20 2 22 × 23 42. 3 1. 23 raida@vut. cz 12

Slot dipole: on-body 2. 4 GHz Impedance characteristics Simulation versus measurements: differences caused by approximate tissue representation raida@vut. cz 13

Slot dipole: radiation patterns yz plane xz plane Radiation in z direction attenuated by the tissue raida@vut. cz 14

Slot dipole: parameters Main lobe level 3. 2 d. Bi Side lobe level (xz plane) 7. 2 d. B Side lobe level (yz plane) 7. 6 d. B Beam width (xz plane) 79 Beam width (yz plane) 98 Radiation efficiency 8. 9% Radiating slot is not separated from the tissue: low efficiency raida@vut. cz 15

Design problems § Vertical polarization ++ Achieved (horizontal slot used) § Horizontal radiation -- Not achieved (slot dipole suitable for off-body link) § Separation from the tissue -- Not achieved (low efficiency) § Reasonable dimensions ++ Achieved (planar structure, fractals) raida@vut. cz 16

Horizontal radiation: horn antenna URBANEC, T. et al. 75/85 GHz experimental wireless link. Proceedings ICEcom 2013, Dubrovnik (Croatia), 2013. raida@vut. cz 17

Horizontal radiation: horn antenna H plane E plane raida@vut. cz 18

Separation: substrate-integrated waveguide KE WU; DESCANTES, D. ; CASSIVI, Y. ; The substrate integrated circuits – a new concept for high-frequency electronics and optoelectronics, TELSIKS 2003, Nis (Serbia and Montenegro), 2003, p. P-III to P-X. raida@vut. cz 19

Separation: SIW § Effective width § Distances between centers of vias § Diameter of vias raida@vut. cz 20

Separation: SIW § To verify the design: CUPAL, M. In-Car Wireless Power Transfer. Diploma Thesis. Brno: Brno University of Technology, 2015. raida@vut. cz 21

Separation: SIW + patch KUFA, M. ; RAIDA, Z. ; VŠETULA, P. ; WOLANSKÝ, D. Filtering antennas: comparison of different concepts, ICEAA 2014, Aruba: Polytecnico di Torino, 2014. raida@vut. cz 22

Separation: SIW + slot Radiator layer Feeding layer LÁČÍK, J. ; MIKULÁŠEK, T. Circular ring-slot antenna fed by SIW for WBAN applications, European Conference on Antennas and Propagation, Eu. CAP 2013. Gothenborg, Sweden: 2013. raida@vut. cz 23

Dimensions: fractals § Self-similar structures Sierpinski monopole Koch loop raida@vut. cz 24

Fractals: dimension reduction raida@vut. cz 25

Fractals: monopole antenna raida@vut. cz 26

Fractals: monopole antenna raida@vut. cz 27

Fractals: multi-band operation f = 0. 495 GHz f = 1. 759 GHz raida@vut. cz f = 3. 181 GHz 28

Fractals: multi-band operation raida@vut. cz 29

Fractals: multi-band operation raida@vut. cz 30

Summary § Vertical polarization: - horizontal slot radiators § Separation from tissues: - feeding by substrate-integrated waveguides § Reasonable dimensions: - miniaturization techniques (e. g. , fractals) § Main-lobe direction: - perpendicular: off-body communication - tangential: on-body communication raida@vut. cz 31