UNR 6285 Deep Underwater Compatible Wi-Fi Antenna Development Hector Fabian Guarnizo Mendez,

Transcription

1 Deep Underwater Compatible Wi-Fi Antenna Development Hector Fabian Guarnizo Mendez, Lab-STICC/MOM, IFREMER Christian GAC, Geoscience Marines dpt., IFREMER Contact : Christian.GAC@ifremer.fr François LE PENNEC, Lab-STICC/MOM, Telecom Bretagne Christian PERSON, Lab-STICC/MOM, Telecom Bretagne 23/03/2012

2 Outline Context Main objectives Technologies comparison (general & radio) Design Seawater electrical properties for EM CAD. Antenna main features and development Results Modeling Measurements Conclusion & Future work ESONET underwater observatory Page 2

3 Page 3 Main Objectives Wireless link High data rate underwater wireless transmissions Very low sensitivity to the variability of the environment conditions Shallow, deep or very deep water (oceanic trenches). Clear or turbid water Bio-pollution resistant Similar environments (petroleum exploration) Usable in underwater observatories Mobile (ROV, AUV) to fixed equipment Remotely Operated Vehicle. Autonomous Underwater Vehicle. Mobile to mobile Economically competitive Low cost relative to the context

4 Technologies comparison * A. Beck et al, Underwater radio frequency communications, in OCEAN 11 proceedings. Page 4

5 Reported UW radio data transmissions ELF & VLF UW radio Frequencies from Hz to KHz Power > KW Typical ranges (KHz) : < 3 kilometer [2008, Mark Rhodes] Data rate :100 b/s [2009, U. M. Cella] VHF UW Radio Frequencies above 1 MHz to 10 MHz Power 10W to 250 W [1972, S. Bogie] Typical Ranges : 100 meters [2007, J Lucas and CK Yip] to 1 meter [2008, Mark Rhodes] Data rate : 500kb/s [2006, Al-Shamma a] UHF UW Radio Swedish military applications (FOI) [2007], no public presentation => our current work A. Al-Shamma'a & al AP IEEE 2004 Page 5

6 Ongoing Page 6

7 Seawater electrical properties for EM CAD EM Properties = f (Frequency, Temperature and Salinity) Selected models from literature Empirical : A. Stogryn, Equations for Calculating the Dielectric Constant of Saline Water (Correspondence), Microwave Theory and Techniques, IEEE Transactions on, vol. 19, n. 8, p , Rigorous (physical) : R. Somaraju et J. Trumpf, Frequency, Temperature and Salinity Variation of the Permittivity of Seawater, Antennas and Propagation, IEEE Transactions on, vol. 54, n. 11, p , Comparison Real part Imaginary part T=15 C, S=35 psu Page 7

8 Antenna main features Electrical 2.45 GHz Wi-Fi compliant, potentially adaptable to other common radio standards Radiation beam oriented mainly Frontally (to compensate axial rotation between moving E/R) Not sensitive to polarization orientation Low sensitivity to natural variability of the intrinsic impedance of the sea Mechanical Compatible with the sea environment Hydrostatic pressure resistant Bio-pollution resistant Good integration capabilities in existing equipment Economic Low cost in comparison with other existing solutions Page 8

9 Antenna concept On body communication Radiating Element Seawater Buffer protection J. Kim, Y. Rahmat-Samii Design of a Dual-Band Implantable Antenna And Development of Skin Mimicking Gels for continuous Glucose Monitoring, IEEE Transactions on Microwave Theory and Techniques, Vol. 56, No. 4, April 2008, pp Buffer protection J. Kim, Y. Rahmat-Samii Implanted Antennas Inside a Human Body: Simulations, Designs, and Characterizations, IEEE Transactions on Microwave Theory and Techniques, Vol. 52, No. 8, August 2004, pp Victor 6000, IFREMER robot [Source: IFREMER] Page 9

10 Antenna design Em. UW Antenna Re. UW Antenna Electric field in the antenna Wi-Fi Low cost Modem Wi-Fi Low cost Modem Circular polarization not required Page 10

11 S 11dB Adaptation (EM simulation) Input reflexion coefficient of the antenna under various conditions T=15 C, S=35 ppt, e r =70.5 In seawater In fresh water With cover 30 cm (er=5) in seawater In air BW@10 db 70 MHz Frequency[GHz] Seawater Cover S Pin 11dB 10 Pref Buffer protection P ref 10.log Pin Page 11

12 S 21 [db] Transmission level (EM simulation) -40 T=15 C, S=35 psu, e r = mm =7.28 db/cm mm S Pout 10.log Pin 21dB mm Emitted power Pin Range Received power Pout Frequency [GHz] Page 12

13 Range estimation Pe( 25 dbm) 100 db T=15 C, S=35 psu, Stogryn, model 12.5 cm Sens(-75 dbm) Instantaneous magnitude of the electric field around the antennas + 1 cm / 7.28 db : little positive effect on the range expected thanks to the antenna gain Page 13

14 S11[dB] 0 Preliminary measurements Ansys HFSS EM CAD software Simulated Measured Frequency [GHz] Sea water in the bucket d Varying d at the top of the antenna does not shift the nominal measured frequency. This confirms the good excitation of the expected EM solution Page 14

15 S11 [db] 0 Advanced prototype Cable losses HFSS software Simulated Measured Frequency [GHz] Due to experimental constraints, the alimentation cables could not be completely deembedded from measurements. Page 15

16 Conclusion EM study of the seawater e r and s = f(temperature, salinity, frequency) Attenuation = GHz Characteristics of the proposed antenna Very simple solution Appropriate for unstable emitter and/or receiver Quasi insensitive to the water variability (fresh, salt) Short range (from 10 to 15 cm, in the seawater) First Experimental investigations Two prototypes realized : one elementary and one more advanced First measurements (input reflexion) confirm EM modelling : nominal resonant frequency and some properties of the excited EM solution in the antenna the nominal frequency does not shift according to either fresh or salt water. Antenna cover has to be compensated by excitation tuning Page 16

17 Future Work Short term Tuning of the second advanced prototype Transmission and radiation measurements in basins Wi-Fi communication tests Medium term Improvement of the antenna sea water conditioning : reduction of the size and suppression of the air in the antenna Tests in-situ (sea bed compatibility) Long term Adaptability to other common radio standards Improvement of the range Page 17