Impedance matching and implementation of planar space-filling dipoles as intraocular implanted antennas in a retinal prosthesis

In this work, an extremely compact planar meander line dipole is designed and implemented for use as an intraocular element in a retinal prosthesis. This planar meander dipole antenna exhibits a high degree of current vector alignment and is impedance matched by inducing a current phase reversal along its length. This current phase reversal is induced by a minor offset in feed location which yields a highly directive broadside radiation pattern on this particular planar antenna geometry. This concept is applied in designing and implementing a 6/spl times/6 mm planar compact wire dipole at 1.4 GHz as the intraocular element for the data telemetry link of a retinal prosthesis. Coupling measurements between an external microstrip patch antenna and the intraocular wire dipole are presented and compared with those obtained with intraocular microstrip patch antennas in place of the wire dipole. It is demonstrated that such compact meander dipoles can perform better than previously reported microstrip patch antennas as intraocular elements for a retinal prosthesis.

[1]  J. Romeu,et al.  The Koch monopole: a small fractal antenna , 2000 .

[2]  E. Zrenner.  Will Retinal Implants Restore Vision ? , 2002 .

[3]  A. Hoorfar,et al.  Bandwidth, cross-polarization, and feed-point characteristics of matched Hilbert antennas , 2003, IEEE Antennas and Wireless Propagation Letters.

[4]  S.R. Best,et al.  On the significance of current vector alignment in establishing the resonant frequency of small space-filling wire antennas , 2003, IEEE Antennas and Wireless Propagation Letters.

[5]  G. Lazzi,et al.  Investigation of a microwave data telemetry link for a retinal prosthesis , 2004, IEEE Transactions on Microwave Theory and Techniques.

[6]  J. Weiland,et al.  Retinal prosthesis for the blind. , 2002, Survey of ophthalmology.

[7]  Malini Narayanan Nadig.  Development of a silicon retinal implant: cortical evoked potentials following focal stimulation of the rabbit retina with light and electricity , 1999, Clinical Neurophysiology.

[8]  S.R. Best,et al.  The effectiveness of space-filling fractal geometry in lowering resonant frequency , 2002, IEEE Antennas and Wireless Propagation Letters.

[9]  Wentai Liu,et al.  Multiple-Unit Artificial Retina Chipset System To Benefit The Visually Impaired , 1998 .

[10]  H.A. Wheeler,et al.  Fundamental Limitations of Small Antennas , 1947, Proceedings of the IRE.

[11]  L. J. Chu.  Physical Limitations of Omni‐Directional Antennas , 1948 .

[12]  W. Liu,et al.  A neuro-stimulus chip with telemetry unit for retinal prosthetic device , 2000, IEEE Journal of Solid-State Circuits.

[13]  Roger F. Harrington,et al.  Effect of antenna size on gain, bandwidth, and efficiency , 1960 .

[14]  S. Stuchly,et al.  Design of microstrip antennas covered with a dielectric layer , 1982 .