THERE IS A REQUIREMENT FOR AN IMPROVED RADOME MATERIAL, WITH A FINER GRAIN STRUCTURE, GREATER STRENGTH AT ELEVATED TEMPERATURES AND GREATER EROSION RESISTANCE (PARTICULARLY TO RAIN) THAN PRESENT MATERIALS.

THERE IS A REQUIREMENT FOR AN IMPROVED RADOME MATERIAL, WITH A FINER GRAIN STRUCTURE, GREATER STRENGTH AT ELEVATED TEMPERATURES AND GREATER EROSION RESISTANCE (PARTICULARLY TO RAIN) THAN PRESENT MATERIALS. THIS NEW MATERIAL MUST BE CAPABLE OF BEING FABRICATED INTO INTRICATE SHAPES WITH ACCURATE DIMENSIONS BY COLD FORMING AND ATMOSPHERIC SINTERING; AND ITS CHANGE IN DIELECTRIC CONSTANT MUST BE LESS THAN 5% IN GOING FROM AMBIENT TEMPERATURES (WHERE THE RADOME IS TUNED) TO 2000 DEG F (ITS TEMPERATURE IN USE) TO MINIMIZE BORESIGHT ERRORS. ONE TYPE OF CERAMIC COMPOSITE WHICH SEEMS TO HOLD PROMISE IS A COMBINATION OF NBALO(4) OR HFSIO(4) MIXED WITH SIO(2) AND BN. THE NBALO(4) AND HFSIO(4) BOTH HAVE HIGHER DIELECTRIC CONSTANTS THAN THE SILICA OR BORON NITRIDE; HOWEVER THEIR HIGH RELATIVE DENSITY WILL PROVIDE PROPORTIONALLY GREATER STRENGTH AND EROSION RESISTANCE. THERE IS A NEED FOR HIGH PURITY POWDERS OF THESE MATERIALS, THAT CAN BE SINTERED TOGETHER INTO DENSE, STRONG, FINE GRAINED RADOME STRUCTURES AT ATMOSPHERIC PRESSURE AND LOW TEMPERATURES.