| 摘要 |
PROBLEM TO BE SOLVED: To provide a Lunberg lens which satisfies required characteristics for both a gain and a side lobe, has high homogeneity, is light in weight and is made low in cost. SOLUTION: The Lunberg lens is produced by adding a blowing agent to a resin mixture obtained by mixing a polyolefin resin and/or a derivative thereof with an inorganic filler of high dielectric constant at a volume ratio of 99 to 50 (resin) : 1 to 50 (filler), pre-expanding the obtained mixture into pre-expanded beads and molding the pre-expanded beads, wherein at least a dielectric expanded layer of 1.50 or higher dielectric constant is formed pre-expanded beads having undergone classification and screening and wherein the value of f(A) represented by the formula f(A) =σa/Aave, in whichσa is a deviation of gas volume fraction (Ar) in the dielectric expanded layer while Aave is an average of gas volume fractions (Ar) at portions of the dielectric expanded layer, satisfies the relationship 0.0005≤f(A)≤0.1. COPYRIGHT: (C)2005,JPO&NCIPI |
