傳統植入式天線架構，通常將上板(superstrate) 覆蓋於天線金屬輻射面上，以防止人體組織直接接觸天線金屬面，本論文提出一新型陶瓷生醫天線架構，設計出ㄧ頻率符合MICS (Medical Implant Communications Services) 402-405 MHz 頻帶之微小化、且寬頻之無上蓋板陶瓷生醫天線，以利於植入人體內並適合應用於植入式無線生醫通訊系統為目標。
本研究所設計無上蓋板的陶瓷生醫植入式天線，將覆蓋於天線金屬輻射面上的上板(superstrate)移除，讓人體組織直接接觸天線金屬面，因此天線可直接利用具高介電係數人體組織作為負載效應以縮小天線尺寸及降低磁波傳播不匹配損失(mismatch loss)。並使用具高介電係數及高品質因數的微波陶瓷生醫相容材料MgTa1.5Nb0.5O6 (εr = 28，Q  f = 35,000)做為天線基板及生醫相容材銀膠(Ag/Pd )合金為天線導線 (conductive line)。
此無上蓋板生醫天線相較於傳統加上蓋板(superstrates)的植入式天線，體積更小且低頗面(low profile 1 mm)，實測的頻寬(BW)約130 MHz，S11為-25 dB。同時將此無上蓋板板陶瓷生醫天線浸泡於仿體液60天後，天線操作頻率與匹配並不會有漂移, 因此證明了直接接觸人體負載之無上蓋板高介電陶瓷天線新型架構，很適合長時間的植入式應用。
最後，我們觀察生醫陶瓷天線置於仿體液中的頻率漂移與輻射增益之變化，結果發現天線寬大操作頻寬足以彌補共振頻率因為製程、基板或上板厚度的變化、置入組織液之深度和不同人體組織所產生的頻率漂移現象。

Traditionally, the antenna architecture for implantable biotelemetry application contains a superstrate covered over the antenna radiation metal parts to prevent from tissue erosion. In this dissertation, novel broadband non-superstrate implantable ceramic antenna architecture is proposed and developed for the applications of implantable biotelemetry system in MICS (Medical Implant Communications Services) 402-405 MHz band. Additionally, both biocompatible materials ceramic MgTa1.5Nb0.5O6, (εr=28, Q  f = 35,000) and sliver palladium alloy (Ag/Pd) are selected for substrate and conductive line of the proposed ceramic antenna, respectively. The metal parts (conductive line of the implantable antenna) are screen-printed on the MgTa1.5Nb0.5O6 ceramic substrate. Both size miniaturization and bandwidth enhancement have been achieved due to direct tissue loading.
Furthermore, compared to other similar implantable antennas covered with superstrate, the advantages of the proposed non-superstrate antenna are: miniaturization and low profile (1 mm), wide measured bandwidth (>130 MHz/33.5 %), deep measured S11 (>-25 dB) at 402 MHz, and gain stability for 0.35 - 0.5 GHz. Moreover, the measured S11 is stable enough even for a period of 60 days and hence it is suitable for the long term implanted biotelemetry applications and demonstrates the feasibility of the novel antenna architecture, direct contact tissue loading and high dielectric constant ceramic substrate.
Finally, to investigate the robust characteristics of the implantable antennas in the emulated dynamic tissue environments, antennas characteristics are evaluated in term of the shifting of resonant frequency and the measured far field radiation gain. It is found that the operating broad fractional bandwidths are enough to cover the shifting of the resonant frequency as the thickness variations of the superstrate or substrate, the implanted depth, and different kinds of human tissues are considered. Thus, both types of developed ceramic antennas are suitable for the biotelemetry applications in the dynamic surrounding tissue environment.

References
[1] R. D. Nevels, D. Arndt, J. Carl, G. Raffoul, and A. Pacifico, “Microwave antenna design for myocardial tissue ablation applications,” in IEEE AP-S Int. Symp. Dig., vol. 3, Newport Beach, CA, June 1995, p. 1572.
[2] A. Rosen, “Microwave applications in cancer therapy, cardiology and measurement techniques: A short overview,” IEEE MTT-S Newslett., pp.17–20, Fall 1990.
[3] M. F. Iskander, A. M. Tumeh, and C. M. Furse, “Evaluation and optimization of the EM characteristics of interstitial antennas for hyperthermia,” Int. J. Radiat., Oncol., Biol., Phys., vol. 18, no. 4, pp. 895–902, Apr. 1990.
[4] R. D. Beach, F. v. Kuster, and F. Moussy, “Subminiature implantable potentiostat and modified commercial telemetry device for remote glucose monitoring,” IEEE Trans. Instrument. Meas., vol. 48, no. 6, Dec. 1999.
[5] W. Liu et al., “A Neuro-Stimulus Chip with Telemetry Unit for Retinal Prosthetic Device,” IEEE J. Solid State Circuits, vol. 35, pp. 1487-1497, Oct. 2000.
[6] C. M. Furse, “Biomedical Telemetry: Today’s Opportunities and Challenges,” Antenna Technology International Workshop on IWAT 2009, pp. 1–4, 2009.
[7] W.-D. Lai and C. T. M. Choi., “Incorporating the Electrode-Tissue Interface to Cochlear Implant Models,” IEEE Trans. Magnetics, vol. 43, no. 4, Apr. 2007.
[8] S. Boyer, M. Sawan, M. A. Gawad, S. Robin, and M. M. Elhilali, “Implantable Selective Stimulator to Improve Bladder Voiding: Design and Chronic Experiments in Dogs”, IEEE Trans. Rehabilitation Engineering, vol. 8, no. 4, Dec. 2000.
[9] W. G. Scanlon, N. E. Evans, and Z. M. McCreesh, “RF performance of a 418 MHz radio telemeter packaged for human vaginal placement,” IEEE Trans. Biomed. Eng., vol. 44, no. 5, pp. 427–430, May 1997.
[10] R. D. Beach, R. W. Conlan, M. C. Godwin, and F. Moussy, “Towards a miniature implantable in vivo telemetry monitoring system dynamically configurable as a potentiostat or galvanostat for two- and three-electrode biosensors,” IEEE Trans. Instrument. Meas., vol. 54, no. 1, Feb. 2005.
[11] European Telecommunication Standards Institute [Online] http://www.etsi.org
[12] “Medical Implant Communications Service (MICS) Federal Register,” Rules and Regulations, vol. 64, no. 240, pp. 69926-69934, Dec. 1999.
[13] C. M. Cheng, Y. C. Chen, C. F. Yang, and C. C. Chan, “Sintering and Compositional Effects on the Microwave Dielectric Characteristics of Mg(Ta1-xNbx)2O6 Ceramics with 0. 25≦x≦0.35,” J. Electroceramics, vol. 18, pp. 155-160, 2007.
[14] F. J. Grau, N. A. Brand, and J. N. Van, US Pat. No. 6,290,501, “Silver-palladium alloys for producing a dental prosthesis which can be covered with dental ceramic,” 2001.
[15] IEEE Standard for Safety Levels with Respect to Human Exposure to Radio Frequency Electromagnetic Fields, 3 kHz to 300 GHz, IEEE Standard, C95.1-1999, 1999.
[16] A. Peyman and C. Gabriel, “Tissue equivalent liquids for SAR measurement at microwave frequencies,” in Proc. Bioelectromagnetics Soc. 24th Ann. Meeting, vol. P-53, 2002, pp. 184-185.
[17] C. Gabriel, S. Gabriel, and E. Corthout, “The dielectric properties of biological tissues: I. Literature survey,” Phys. Med. Biol., vol. 41, pp. 2231-2249, 1996.
[18] R. N. Simons, “Coplanar Waveguide Circuits, Components, and Systems”, Wiley-series in Micro. and Optical Eng., New York.
[19] A. J. Johansson, “Wireless communication with medical implants: antennas and propagation,” PhD thesis, Lund University, Sweden, pp. 13-15, 2004.
[20] M. Ballen, M. Kanda, C. K. Chou, and Q. Balzano, “Formulation and characterization of tissue simulating liquids used for SAR measurement,” in Proc. Bioelectromagnetics Soc. 23rd Ann. Meeting, vol. 14-3, p. 80, 2001.
[21] J. P. Grant, R. N. Clarke, G. T. Symm, and N. M. Spyrou, “A critical study of the open-ended coaxial line sensor technique for RF and microwave complex permittivity measurements,” J. Phys. E: Sci. Instrum., vol. 22, pp. 757-770, 1989.
[22] K. Fukunaga, S. Watanabe, and Y. Yamanaka, “Dielectric Properties of Tissue-Equivalent Liquids and Their Effects on Specific Absorption Rate”, IEEE Trans. Electromagnetic Compatibility, vol. 46, no. 1, pp. 126-129, Feb. 2004.
[23] International Telecommunication Union, Recommendation ITU-R SA.1346, 1998.
[24] T. Karacolak, A. Z. Hood, and E. Topsarkal, “Design of a Dual-Band Implantable Antenna and Development of Skin Mimicking Gels for Continuous Glucose Monitoring,” IEEE Trans. Microw. Theory Tech., vol. 56, pp. 1001-1008, Oct. 2008.
[25] S. Soora, K. Gosalia, M. S. Humayun, and G. Lazzi “A comparison of two and three dimensional dipole antennas for an implantable retinal prosthesis,” IEEE Trans. Antennas Propag., vol. 56, no. 3, pp. 622-629, Mar. 2008.
[26] S. Pichitpong, C. M. Furse, and C. C. You, “Design of Implantable Microstrip Antenna for Communication with Medical Implants,” IEEE Trans. Microw. Theory Tech., vol. 52, pp. 1944-1951, Aug. 2004.
[27] P. Izdebski, H. Rajagopalan, and Y. Rahmat.-Samii, “Conformal Ingestible Capsule Antenna: A Novel Chandelier Meandered Design,” IEEE Trans. Antennas Propag., vol. 57, pp. 900-909, Apr. 2009.
[28] W. C. Liu, S. H. Chen, and C. M. Wu, “Implantable Broadband Circular Stacked PIFA Antenna for Biotelemetry Communication,” J. of Electromagn. Waves and Appl., vol. 22, pp. 1791-1800, Apr. 2008.
[29] C. M. Lee, T. C. Yo, F. J. Huang, and C. H. Luo, “Bandwidth Enhancement of Planar Inverted F Antenna for Implantable Biotelemetry,” Micro. Opt. Tech. Lett., vol. 51, pp. 749-751, 2009.
[30] K. F. Tong, K. M. Luk, C. H. Chan, and E. K. N. Yung, “A miniature monopole antenna for mobile communications,” Micro. Opt. Tech. Lett., vol.27, pp. 262-263, 2000.
[31] H. C. Liu, T. S. Horng and N. G. Alexopoulous, "Radiation of printed antennas with a coplanar waveguide-fed," IEEE Trans. Antennas Propag., vol. 10, pp. 1143-1148, Oct. 1995.
[32] T. Dissanayake, K. P. Esselle, and M. R. Yuce, “Dielectric Loaded Impedance Matching for Wideband Implanted Antennas,” IEEE Trans. Microw. Theory Tech., vol. 57, no. 10, pp. 2480-2487, Oct. 2009.
[33] J.-R. Lee, J.-H. Cho, and S.-W.S.-Won Yun, “New compact bandpass filter using microstrip /4 resonators with open stub inverter,” IEEE Microwave Guided Wave Lett., vol. 10, pp. 526-527, Dec. 2000.
[34] M. J. Ammann and Z. N. Chen, “Wideband monopole antennas for multi-band wireless systems,” IEEE Antennas and Propag. Mag., vol. 45, No. 2, pp. 146-150, Apr. 2003.
[35] J. Jung, K. Seol, W. Choi, and J. Choi, “Wideband monopole antenna for various mobile communication applications”, Electron. Lett., vol. 41, pp. 1313-1314, Nov. 2005.
[36] W. Wang, S. S. Zhong, and S. B. Chang, “A novel wideband coplanar-fed monopole antenna”, Microw. Opt. Tech. Lett., vol. 43, pp. 50-52, Oct. 2004.
[37] W. S. Lee, D. Z. Kim, K. J. Kim, and J. W. Yu, “Wideband planar monopole antennas with dual band-notched characteristics”, IEEE Trans. Microw. Theory Tech., vol. 54, no. 6, pp. 2800-2806, June. 2006.
[38] Z. N. Chen, G. C. Liu, and T. S. P. See, “Transmission of RF Signals Between MICS Loop Antennas in Free Space and Implanted in the Human Head,” IEEE Trans. Antennas Propag., vol. 57, pp. 1850-1854, Jun. 2009.
[39] W. Xia, K. Saito, M. Takahashi and K. Ito, “Performances of an Implanted Cavity Slot Antenna Embedded in the Human Arm,” IEEE Trans. Antennas Propag., vol. 57, pp. 894-899, Apr. 2009.
[40] L. Aberbour and C. Craeye, “On the Radiation Resistance of Planar Monopole Antennas,” IEEE Trans. Antennas Propag., vol. 57, pp. 1035-1042, Apr. 2009.
[41] T. F. Chien, H. C. Yang, C. M. Cheng, and C. H. Luo, “Develop CPW-Fed Monopole Broadband Implanted Antennas on the High Dielectric Constant Ceramic Substrates,” Micro. Opt. Tech. Lett., vol. 52, pp. 2136-2139, Sep. 2010.
[42] A. Mahanfar and R. G. Vaughan, “The Effect of Buffer Superstrate on the Performance of Implanted Patch-Type PIFA and Microstrip Antennas-A Comparative Study”, EMTS Electromagnetic Theory Symposium, July 2007.
[43] J. Kim and Y. Rahmat-Samii, “Implanted antennas inside a human body: Simulations, designs, and characterizations,” IEEE Trans. Microw. Theory Tech., vol. 52, no. 8, pp. 1934-1943, Aug. 2004.
[44] R. Warty, M. Tofighi, R. U. Kawoos, and A. Rosen, “Characterization of implantable antennas for intracranial pressure monitoring: Reflection by and transmission through a scalp phantom,” IEEE Trans. Microw. Theory Tech., vol. 56, no. 10, pp. 2366-2376, Oct. 2008.
[45] S. Gabriel, R. W. Lau, and C. Gabriel, “The dielectric properties of biological tissues: II. Measurements in the frequency range 10 Hz to 20 GHz,” Phys. Med. Biol., vol. 41, pp. 2251-2269, 1996.
[46] IEEE Standard 145-1983, IEEE standard definitions of terms for antennas, pp. 7-22, June 1983.
[47] J. D. Kraus, “Antennas Since Hertz and Marconi,” IEEE Trans. Antennas Propag., vol. 33, NO. 2, pp. 131-137, Feb. 1985.
[48] Ansoft High Frequency Structure Simulator (HFSS), Ver. 10.1, Ansoft Corporation, 2006
[49] M. Ballen, M. Kanda, C. K. Chou, and Q. Balzano, “Formulation and characterization of tissue simulating liquids used for SAR measurement,” in Proc. Bioelectromagnetics Soc. 23rd Ann. Meeting, vol. 14-3, pp. 80, 2001.
[50] J. P. Grant, R. N. Clarke, G. T. Symm, and N. M. Spyrou, “A critical study of the open-ended coaxial line sensor technique for RF and microwave complex permittivity measurements,” J. Phys. E: Sci. Instrum., vol. 22, pp. 757-770, 1989.
[51] John D. Kraus and Ronald J. Marhefka.: “Antennas for all applications”, 2003
[52] C. A. Balanis , "Antenna Theory: Analysis and Design", 2005
[53] C. M. Lee, “The Implementation of Antenna for Implantable Biotelemetry System and the Design of Broadband Antenna,” PhD thesis, National Cheng Kung University, Taiwan, 2009