Electromagnetic energy coupler/receiver apparatus and method

• US 4,240,445 A
• Filed: 10/23/1978
• Issued: 12/23/1980
• Est. Priority Date: 10/23/1978
• Status: Expired due to Term

• Current Assignee: University of Utah Research Foundation (State of Utah)
• Original Assignee: University of Utah (State of Utah)
• Inventors: Iskander, Magdy F., Durney, Carl H.
• Primary Examiner(s): Cohen, Lee S.
• Application Number:
  US05/954,054
• Time in Patent Office: 792 Days
• Field of Search: 128/804, 128/783, 128/800, 128/802, 128/653, 128/734, 219/10.79, 336/66
• US Class Current: 607/156
• CPC Class Codes: A61B 5/05 Detecting, measuring or recording for diagnosis by means of electric currents or magnetic fields; Measuring using microwaves or radio waves impedance plethysmography A61B5/0295; measuring movement of the entire body or parts thereof A61B5/11; detecting, measuring or recording bioelectric or biomagnetic signals of the body or parts thereof A61B5/24
• CPC Class Codes: A61B 5/0507 using microwaves or terahertz waves
• CPC Class Codes: A61N 5/04 Radiators for near-field treatment
• CPC Class Codes: H01P 5/085 Coaxial-line/strip-line transitions
• CPC Class Codes: H01P 5/10 for coupling balanced lines or devices with unbalanced lines or devices
• CPC Class Codes: H01Q 1/38 formed by a conductive layer on an insulating support patch antennas H01Q9/0407; microstrip dipole antennas H01Q9/065; microstrip slot antennas H01Q13/106; transmission line microstrip antennas H01Q13/206; manufacturing reflecting surfaces using insulating material for supporting the reflecting surface H01Q15/142
• CPC Class Codes: H01Q 13/08 Radiating ends of two-conductor microwave transmission lines, e.g. of coaxial lines, of microstrip lines

Abstract

An apparatus and method for coupling electromagnetic energy into a dielectric material such as tissue while substantially reducing external leakage of the energy. The apparatus may also be used as a receiver for electromagnetic energy transmitted through tissue. The apparatus includes an open transmission line which is inherently non-radiating and may be configurated with a centrally disposed, central strip conductor. A ground plane conductor is placed in spaced relationship to the central strip conductor and on both sides of the central strip conductor. Alternatively, the central strip conductor may be placed in spaced relationship to one side of a ground plane conductor. The central strip conductor is terminated with a resistor of resistance equal to the characteristic impedance of the open transmission line. The spacing and electrical geometry of each of the central strip conductor, ground plane conductor, electrical interconnection points, and the resistor are each selectively predetermined to minimize spurious radiation during coupling of the transmission apparatus. The method includes minimizing external leakage of electromagnetic energy while coupling electromagnetic energy with tissue using the apparatus of this invention.

Claims

1. An apparatus for coupling electromagnetic energy into a material comprising:

a substrate body of dielectric material, the body having an external surface;

an open transmission line mounted at the external surface of the dielectric substrate to accommodate access to electromagnetic fields adjacent the open transmission line, the open transmission line serving as an inducing means for inducing electromagnetic energy into the material and comprising a central strip conductor and a ground plane conductor, the central strip conductor being surrounded in spaced relationship by the ground plane conductor, the open transmission line further comprising a resistor electrically interconnecting the central strip conductor and the ground plane conductor; and

means for connecting the open transmission line with a source of electrical energy to thereby allow the open transmission line to operate as an inducing means.

2. The apparatus defined in claim 1 wherein the open transmission line comprises a predetermined spatial relationship between the central strip conductor and the ground plane conductor, the spatial relationship being selectively predetermined for smooth wave propagation with reduced transition losses.

3. An apparatus for coupling electromagnetic energy into a material comprising:

a substrate body of dielectric material, the body having an external surface, the dielectric substrate further comprising handle means for handling the apparatus;

an open transmission line mounted at the external surface of the dielectric substrate to accommodate access to electromagnetic fields adjacent the open transmission line, the open transmission line serving as an inducing means for inducing electromagnetic energy into the material and comprising a central strip conductor and a ground plane conductor, the central strip conductor being surrounded in spaced relationship by the ground plane conductor, the open transmission line further comprising a resistor electrically interconnecting the central strip conductor and the ground plane conductor; and

means for connecting the open transmission line with a source of electrical energy to thereby allow the open transmission line to operate as an inducing means.

4. The apparatus defined in claim 3 wherein the means for connecting the open transmission line with a source of electrical energy further comprises a coaxial cable electrically connected with the central strip conductor and the ground plane conductor, the handle means serving as a stabilizing means for the coaxial cable.

5. The apparatus defined in claim 3 wherein the central strip conductor and the ground plane conductor further comprise an overlayment, the overlayment having dielectric properties similar to the material to enhance electromagnetic coupling when the open transmission line is placed adjacent the material.

6. A method for coupling electromagnetic energy to a dielectric material comprising:

fabricating an open transmission line for electromagnetic energy by obtaining a body of dielectric substrate having a surface and mounting the open transmission line at the surface of the body of dielectric substrate, the open transmission line comprising a central strip conductor mounted at the surface of the body of dielectric substrate and surrounded in spaced relationship by a ground plane conductor mounted at the surface of the body of dielectric substrate and a resistor electrically interconnecting the central strip conductor with the ground plane conductor;

interconnecting the open transmission line with a source of electromagnetic energy; and

coupling the electromagnetic energy into the dielectric material by bringing the open transmission line into at least close proximity with the dielectric material thereby inducing electromagnetic fields in the dielectric material.

7. A microwave coupler for coupling microwave energy to tissue comprising:

a dielectric substrate configurated with a surface adapted to be placed against the tissue;

an open transmission line mounted to the surface of the dielectric substrate, the open transmission line comprising a central strip conductor, a ground plane conductor, and a resistor, the central strip conductor being surrounded in spaced relationship by the ground plane conductor and electrically interconnected to the ground plane conductor by the resistor; and

means for connecting the open transmission line to a source of electromagnetic energy, the electromagnetic energy inducing microwave energy in the open transmission line.

8. A method for coupling microwave energy into tissue comprising:

forming a microwave applicator as an open transmission line by placing a first conductor on a dielectric substrate as a central strip conductor and mounting a second conductor on the dielectric substrate as a ground plane conductor, the ground plane conductor in spaced relationship and electrically interconnecting the central strip conductor with the ground plane conductor with a resistor;

interconnecting the open transmission line with a source of electromagnetic energy, the electromagnetic energy inducing microwave energy with the open transmission line; and

coupling the microwave energy into the tissue by bringing the microwave applicator into proximity with the tissue thereby inducing fields in the tissue.