Microwave field detector
AssigneeIowa State University Research Foundation, Inc.
InventorGlenn Ellsworth Fanslow
Life of this patent
Estimating the term…
Abstract
Liquid crystals having color play centered at different temperatures are arranged in a similar pattern on metal coated and non-metal coated disks which are used to monitor electromagnetic radiation. An embodiment which measures radiation in the range of 1 to 15 mW/cm.sup.2 at 2.45 GHz is described. The monitor uses the temperature-dependent light scattering properties of liquid crystals as the measuring and indicating mechanism. While both disks will respond equally to changes in ambient temperature, the metal coated disk also responds to induced temperature changes caused by incident radiation. Thus the difference between the temperature indications of the two disks is a measure of the radiation present.
Claims20
A detector for determining the intensity of a microwave field comprising:
- a layer of resistive material adapted to receive said microwave field for providing induced internal electrical currents in response thereto thereby establishing a temperature on said layer corresponding to the microwave field;
- a first plurality of regions of temperature sensitive film means disposed in thermal conducting relation with said layer of resistive material for facilitating heat transfer between said film means and said layer and for providing a visible color play representative of said temperature, each region exhibiting color play at a different temperature and said regions arranged in spaced relation in a predetermined pattern;
- a second plurality of regions of temperature sensitive film means disposed in thermal isolating relation with said layer of resistive material to inhibit heat transfer between said second plurality of film means and said layer, each region of said second plurality corresponding to an associated region of said first plurality and exhibiting a corresponding color play at the same temperature as the associated region, all of said regions of said second plurality being arranged in a pattern similar to the pattern of said first regions;
- whereby one region of said second plurality has a given visible display responsive only to ambient temperature, and a region of said first plurality exhibits color play responsive to the cumulative effect of ambient temperature and heating in the resistive layer due to incident microwave energy, the difference in color play of said first and second plurality of regions being a measure of the intensity of microwave energy.
A detector for determining the intensity of a microwave field comprisng a main detection unit and a reference detection unit, both mounted on a common support means;
- each of said detection units having a plurality of areas with temperature sensitive means, arranged in corresponding pairs of said areas, each pair having one area on the main detection unit and one area on the reference detection unit, the two areas of a pair being sensitive to substantially the same temperature range, and the pairs being sensitive to different temperature ranges arranged in a graduated pattern;
- a continuous layer of resistive material adjacent to only said areas of the main detection unit, adapted to receive said microwave field for providing induced electrical currents to produce heating corresponding to the intensity of the microwave field;
- so that both detection units respond to ambient heating conditions, while only the main detection unit responds to a microwave field;
- and observation of one area of the main detection unit having a given display and one area of the reference detection unit having a given display is used to determine the intensity of the microwave field.
Dependencies are inferred from the claim text.