Dual mode intracranial temperature detector

Apparatus for detecting thermal radiation emanating from two different depths in a patient, said apparatus comprising a dual-mode transducer having a working surface for placement against a patient's cranium, said transducer including

• a first antenna extending along an axis to a first end defining a first aperture at or adjacent said working surface, said first antenna having a characteristic first antenna pattern that extends a selected first distance along said axis from said working surface and being tuned to a first frequency, said first antenna producing a first output signal indicative of thermal radiation received within said first antenna pattern, wherein the transducer also includes
• a second antenna extending along said axis to a second end adjacent to said working surface and defining a second aperture which is shared with the first aperture, said second antenna being isolated from the first antenna and having a characteristic second antenna pattern that extends a selected second distance along said axis from said working surface within the envelope of the first antenna pattern and being tuned to a second frequency, said second antenna producing a second output signal indicative of thermal radiation received within said second antenna pattern, said second distance being appreciably shorter than said first distance,
• wherein the first antenna comprises a first waveguide having a first aperture constituting said first end,
• wherein the first waveguide includes a side wall extending from the first aperture to a closed end spaced from the first aperture, and a septum extending between opposite locations on the side wall so as to partition the first aperture, and
• wherein the second antenna extends along said axis within the septum.