Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
250 words
Apparatus for use in microwave thermography, said apparatus comprising a signal-receiving aerial sensitive to microwave radiation emanating from a portion of a living-tissue body, said body having a mean body temperature and a mean tissue impedance and said aerial having an output for delivering a thermal noise signal representative of said microwave radiation, a single-throw on-off solid state diode microwave switch connected to said aerial output, a fixed-impedance reference load which is maintained at a predetermined temperature substantially equal to said mean body temperature and said reference load having an output capable of emitting a thermal noise signal at microwave frequency corresponding to that predetermined temperature, a receiver having an input with an input impedance matched to the impedance of said reference load said receiver having an output and switchable detection means for establishing at said output the difference between the thermal noise signals delivered to the receiver input and emanating from said aerial and from said reference load, synchronous switching means connected to drive said detection means and said solid-state diode microwave switch, a three-port non-reciprocal circulator interconnecting said aerial, reference load and receiver, said circulator having respective ports taken in circulation order connected to the noise-signal output of said reference load, to the output of the aerial via said single-throw on-off diode microwave switch, and to the receiver input, and adding means connected to the output of the receiver and to the output of the reference load for establishing a measure of the temperature of said body portion.
Claim 2
Dependent Claim
250 words
Apparatus for use in microwave thermography, said apparatus comprising a signal-receiving aerial sensitive to microwave radiation emanating from a portion of a living-tissue body, said body having a mean body temperature and a mean tissue impedance and said aerial having an output for delivering a thermal noise signal representative of said microwave radiation, a single-throw on-off solid state diode microwave switch connected to said aerial output, a fixed-impedance reference load which is maintained at a predetermined temperature substantially equal to said mean body temperature and said reference load having an output capable of emitting a thermal noise signal at microwave frequency corresponding to that predetermined temperature, a receiver having an input with an input impedance matched to the impedance of said reference load said receiver having an output and switchable detection means for establishing at said output the difference between the thermal noise signals delivered to the receiver input and emanating from said aerial and from said reference load, synchronous switching means connected to drive said detection means and said solid-state diode microwave switch, a three-port non-reciprocal circulator interconnecting said aerial, reference load and receiver, said circulator having respective ports taken in circulation order connected to the noise-signal output of said reference load, to the output of the aerial via said single-throw on-off diode microwave switch, and to the receiver input, and adding means connected to the output of the receiver and to the output of the reference load for establishing a measure of the temperature of said body portion.
Claim 3
Dependent Claim
14 words
Apparatus as claimed in claim 1, wherein said non-reciprocal circulator is a ferrite circulator.
Claim 4
Dependent Claim
119 words
Apparatus as claimed in claim 1, wherein said aerial comprises a tubular metallic waveguide having a radiation receiving end of circular cross-section dimensioned to receive radiation modes up to and including TE 11 , said tubular metallic waveguide having a signal output end incorporating a coaxial cable connection, a broad-band-waveguide to coaxial-line mode transformer connected between the receiving end and the output end of said tubular metallic waveguide and arranged to deliver only radiation of the TE 11 mode to the coaxial cable connection, and the interior of the tubular metallic waveguide being filled with low-loss dielectric material providing the aerial with a planar radiation-receiving-end face and a receiving-end impedance close to the mean tissue impedance of said body.
Claim 5
Dependent Claim
20 words
Apparatus as claimed in claim 3, wherein said radiation receiving end impedance is in the range 60 to 150 ohms.