Microsphere-filled-metal components for wireless-communication towers

Abstract

A wireless-communications-tower component being at least partially formed from a microsphere-filled metal. The microsphere-filled metal has a density of less than 2.7 g/cm 3 , a thermal conductivity greater than 1 W/m·K, and a coefficient of thermal expansion of less than 30 μm/m·K. Microspheres suitable for use in such microsphere-filled metal include, for example, glass microspheres, mullite microspheres, alumina microspheres, alumino-silicate microspheres, ceramic microspheres, silica-carbon microspheres, carbon microspheres, and mixtures of two or more thereof.

1 . An apparatus, comprising:
 a wireless-communications-tower component being at least partially formed from a microsphere-filled metal,   wherein said microsphere-filled metal has a density of less than 2.7 grams per cubic centimeter (“g/cm 3 ”) measured at 25° C.   
     
     
         2 . The apparatus of  claim 1 , wherein the metal of said microsphere-filled metal is selected from the group consisting of aluminum, magnesium, and their alloys. 
     
     
         3 . The apparatus of  claim 1 , wherein said microsphere-filled metal has a thermal conductivity of greater than 1 watt per meter Kelvin (“W/m·K”) measured at 25° C., wherein said microsphere-filled metal has a linear, isotropic coefficient of thermal expansion (“CTE”) of less than 30 micrometers per meter Kelvin (“μm/m·K”) over a temperature range of −35 to 120° C. 
     
     
         4 . The apparatus of  claim 1 , wherein said microsphere-filled metal has a density ranging from 0.6 to 2 g/cm 3  measured at 25° C., wherein said microsphere-filled metal has a thermal conductivity ranging from 5 to 150 W/m·K W/m·K measured at 25° C., wherein said microsphere-filled metal has a linear, isotropic CTE ranging from 8 to 25 μm/m·K over a temperature range of −35 to 120° C. 
     
     
         5 . The apparatus of  claim 1 , wherein said microsphere-filled metal has a tensile strength ranging from 0.8 to 60 Kpsi. 
     
     
         6 . The apparatus of  claim 1 , wherein said microsphere-filled metal comprises microspheres selected from the group consisting of glass microspheres, mullite microspheres, alumina microspheres, alumino-silicate microspheres, ceramic microspheres, silica-carbon microspheres, carbon microspheres, and mixtures of two or more thereof. 
     
     
         7 . The apparatus of  claim 6 , wherein said microspheres have a particle size distribution D10 ranging from 8 to 30 μm, a D50 ranging from 10 to 70 μm, and a D90 ranging from 25-120 μm, wherein said microspheres have a true density ranging from 0.1 to 0.7 g/cm 3 . 
     
     
         8 . The apparatus of  claim 6 , wherein said microspheres constitute in the range of from 1 to 95 volume percent based on the total volume of said microsphere-filled metal. 
     
     
         9 . The apparatus of  claim 1 , wherein said wireless-communications-tower component is selected from the group consisting of a radio frequency (“RF”) cavity filter, a heat sink, an enclosure, a tower-top support accessory, and combinations of two or more thereof. 
     
     
         10 . The apparatus of  claim 1 , wherein said wireless-communications-tower component is an RF cavity filter, wherein at least a portion of said microsphere-filled metal is copper and/or silver plated.