Enhanced paint for microwave/millimeter wave radiometric detection applications and method of road marker detection

DETAILED DESCRIPTION In accordance with the forgoing objects, an improved roadway marker detection method employs a vehicle or other wheeled platform capable of movement along the roadway surface.
The vehicle supports a downwardly inclined looking radiometer a short distance above the roadway.
The vehicle is then moved along the roadway and the MMW radiometric energy, reflected and/or emitted from the various patches of road surface and viewed as the vehicle progresses forward, is monitored and may be displayed.
Any roadway markers encountered along the way are detected by a significant decrease in energy received by the radiometer as a result of viewing energy from the "cold" sky.
Unlike prior systems, the foregoing method distinguishes markers in rain or fog and in day or at night, with wet or snow covered roadways.
Markers are detected passively.
It is not necessary to emit electromagnetic radiation into the environment to make the detection, minimizing risks to personnel and avoiding possible interference to other electronics equipment.
Moreover, since artificial illumination is unnecessary, the roadway infrastructure requirements are simplified.
In accordance with another aspect to the invention, a new roadway marker paint possesses enhanced MMW radiometric energy reflection characteristics obtained by incorporation of metal particles and/or high dielectric particles within the thermoplastic material of ordinary road marker paint.
A preferred embodiment of the enhanced radiometric paint includes size 20 or 30 iron shot with the iron shot comprising approximately 30% of the paint mixture by volume.
When the foregoing inspection procedure is made of markers constructed in that way, the decrease in detected temperature is larger than before on some surfaces, such as asphalt, although the change is not as great on concrete.
This evidences an increased radiometric contrast between the marker and the adjacent pavement.
As a benefit the new radiometric paint may be applied to the roadway using existing paint striping equipment