Abstract: A physiologic facsimile image of a biological target without multipath comination is obtained by first producing, for each one of a plurality of sample locations which are spaced so as to define a two-dimensional array, a time delay spectrum wherein the frequency of each spectral ordinate represents the instantaneous differential propagation delay between a first microwave signal which has been propagated through the target and a second microwave signal which initially corresponds to the first microwave signal, and which has been propagated through means having a predetermined propagation delay, and measuring the amplitude of the spectral ordinate corresponding to the direct ray path of propagation through the target, so as to obtain a set of data. The set of data is then digitized and converted from time domain to frequency domain.

Abstract: A physiologic facsimile image of a biological target is obtained by: scang the target by transmitting a microwave signal through the target and measuring at least one of the amplitude and phase components of the complex microwave power transmission coefficient at each one of a plurality of sample locations which are spaced so as to define a two-dimensional array and such that a set of digital data for each of the measured components is obtained, and for at least one of the sets of data; sorting the set of data into column order; magnifying data derived from the sorting step so as to enhance the resolution of the image; mapping data derived from the magnifying step into further data using a predetermined mapping function so as to enhance the contrast between selected portions of the image; and obtaining the set of control signals by filtering data derived from the mapping step using a band pass function which rejects spatial frequencies below a predetermined first frequency and/or rejects spatial frequencies a

Abstract: A rapid and accurate method for calibrating an instrument for measuring the reflection coefficient and complex permittivity of unknown dielectric materials in a lumped capacitance method for an automatic network analyzer is described. The method includes the discovery that the capacitance of the instrument filled with air can be calculated by measuring only the reflection coefficients of the instrument filled with air and filled with a standard liquid of known permittivity, without the necessity of calculating the capacitance value from the dimensions of the instrument. The complex permittivity of the unknown can then be calculated by measuring the reflection coefficient of the instrument filled with the unknown dielectric. Complex permittivity measurements are useful in, for example, evaluating the time course of dielectric dispersions in biological samples.

Abstract: A method for electromagnetic analysis of cellular or cell ghost physiology and pharmacology without disrupting the physcial integrity of the cell membrane is described. The method utilizes the technique of multifrequency automatic network analysis and signal processing to derive complex permittivities from the error corrected complex reflection coefficient of cell containing samples at each measured frequency. Complex permittivity at each frequency is then related to the dispersion in dielectric conductivity (a term which includes ohmic and non-ohmic losses) thereby measuring the ion permeability barrier and transport functions of the cell membrane and ion distribution inside of and outside of the cell membrane. The method measures the complex reflection coefficient of a capacitive termination containing a cellular sample as high frequencies are applied.

Abstract: A system for remote microwave interrogation and imaging of biological tars comprises at least one microwave, double ridged waveguide antenna probe which operates at S-band frequencies, and a high dielectric liquid medium, preferably water, in which both the probe and the target are completely immersed. For imaging applications, the probe is positioned with respect to the target such that the target is in the near field of the antenna.

Abstract: A thermometric transducer device is provided for use in measuring the temperature of a dielectric, such as human tissue, during exposure of the dielectric to microwave radiation. The system includes a transducer electrode sub-assembly which is partially inserted into the dielectric and comprises a thermistor mounted on one end of an elongate substrate and thick film conductors which extend along the length of the substrate and which are tapered so as to provide electrothermal matching of the heat produced in an equivalent volume of the dielectric so that the transducer electrode serves neither as a heat source or a heat sink. The transducer sub-assembly is connected to measurement instrumentation by a transmission line formed by ultra-thin thin film conductors whose thickness relative to the skin depth of the microwave field in the conductors is such that the conductors are a poor medium for microwave conduction and are thus microwave decoupled.

Abstract: Remote interrogation of biological targets is accomplished in accordance h the present invention by method and apparatus wherein a microwave signal is generated which varies in frequency from a first frequency to a second frequency in a predetermined time period. The signal is divided into two signals, one of which is propagated through a test channel comprising a transmitting antenna for transmitting the signal through the target, and a receiving antenna for receiving the signal transmitted through the target, and the other of which is propagated through a reference channel providing a fixed time delay of propagation. The propagated signals are detected and mixed to produce a time delay spectrum wherein the frequency of each spectral line represents the instantaneous difference in the frequencies of the detected signals.