Passive millimeter wave sensor using high temperature superconducting leads

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention is best understood when considered with reference to the drawings, wherein the (not to scale) drawings are directed to particular embodiments intended to illustrate but not limit the ensuing claims.
In accordance with the preferred embodiment of the present invention, FIG.
1 depicts in overhead view a radiation sensor 20.
A thermal detector unit 22 is disposed in the center of a multi-segment antenna 24.
The thermal detector unit 22 may be a bolometer, a pyroelectric element, a thermopile element, or any suitable thermal sensing element.
A typical thermal detector unit defines a multilayer structure wherein a film of vanadium oxide is supported on a bridge isolated layer of a material such as silicon nitride.
The antenna 24 preferably defines an orthogonal pair of planar full-wave dipoles (a crossed bowtie configuration) as described in U.
S.
Pat.
No.
5,450,053 (herein incorporated by reference) and in co-owned U.
S.
Pat.
No.
6,329,655.
Such a configuration is particularly adapted to be responsive to a particular frequency band of incident radiation.
The antenna 24 may define other configurations or shapes, such as a spiral coil, as may be appropriate for a particular radiation frequency band of interest.
Particular frequency bands of interest include bands centered at approximately 35 GHz, 94 GHz, 140 GHz, and 220 GHz.
The antenna 24 may alternatively be located at some distance from the detector 22.
The antenna 24 is typically fabricated from a conductive metal such as aluminum or copper.
For the crossed bowtie configuration selected for illustration, the antenna 24 is divided into pairs of opposed trapezoidal leaves 24A 24B and 24C 24D.
Each leaf 24A, 24B of one pair is orthogonal to each leaf 24C, 24D of the other pair.
Preferably, each of the trapezoidal leaves 24A 24D define a distance .
DELTA.
x between an inward facing edge or surface 26A 26D of each respective leaf 24A 24D and an adjacent edge or surface 28 of the thermal detector unit 22