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Abstract

Method and apparatus for in vivo or in vitro sensing of complex dielectric properties of lossy dielectric materials, particularly biological tissue. Configured as a needle-like dielectric sensor, a coaxial cable (1) having a circumferential gap (12) in the shield (2) is wrapped with an electrically thin dielectric substrate (18). The cable center conductor (6) extends immediately past gap (12) and is shorted to cable shield (2). A thin conductive dipole resonator (16) is positioned on substrate (18) and over feed gap (12) to achieve inductive coupling between the cable center conductor (6) and the dipole resonator (16) through gap (12). Superstrate (22), which could be a dielectric catheter, covers the entire sensor assembly (10). By measurement of the resonator resonant frequency and the input impedance matching factor at the resonant frequency, the real and imaginary dielectric components (.epsilon.', .epsilon.') of the test material into which the sensor is inserted are determined.

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