Patent Number: 055524559
Section: claims

1. A radar absorbing material comprising a binder material containing a mixture of two groups of spheres made of a magnetic material, said first group having a specific average diameter and said second group having an average diameter generally 0.73 times the specific average diameter of said spheres of said first group, said first and second groups containing generally equal numbers of spheres and the amount of said binder material just sufficient to both bind said mixture together while maintaining said individual spheres separated from each other. 2. The material as set forth in claim 1 were in said magnetic material is made of iron. 3. The material as set forth in claim 2 wherein said average diameter of said first group of spheres is 5 microns. 4. The material as set forth in claim 1, or 2, or 3 wherein the binder materical is a resin. 5. The material as set forht in claim 1, or 2, or 3 wherein the binder material is a ceramic. 6. A process for the manufacture of a radar absorbing material comprising the steps of: providing a first group of spheres made of a magnetic material, said spheres having and average diameter;  providing a second group of spheres made of a magnetic material containing a number of spheres equal to the number of spheres of said first  group with an average diameter of generally 0.73 times the average diameter of said spheres of said first group;  mixing said first and second groups of spheres together forming a mixture;  mixing an amount of binder matrix material to said mixture sufficient to both bind said mixture together while maintaining the individual spheres separated from each other; and  curing said resin matrix material.  determining the number of particles in equal volume samples of each of said groups; and plotting the particle diameter distribution of each of said volume samples;  normalizing the plot of one of said sample plots of particle distributions;  overlaying said normalized plot on the non-normalized plot; and  applying a multiplication factor to the values of the smaller of said normalized and non-normalized plots until a best fit between the two is achieved. 7. The process as set forth in claim 6 wherein said first and second group of spheres have diameters in a generally Gaussian distributions about said average diameters, said step of providing a second group of spheres made of a magnetic material containing a number of spheres equal to the number of spheres of said first group with an average diameter of generally 0.73 times the average diameter of said spheres of said first group comprises the steps of: 8. The process as set forth in claim 7 where in said step of mixing said first and second groups of spheres together forming a mixture includes the step of mixing said first and second groups of spheres in a weight ratio equal to the multiplication factor providing the best fit between said normalized plot and said non-normalized plot. 9. The process as set forh in claim 6, or 7, or 8 wherein in said binder material is a resin and the step of solidifying includes the step of curing said resin. 10. The process as set forth in claim 6, or 7, or 8 wherein said binder is a ceramic and the step of solidifying the binder includes the step of curing the ceramic.