▎ 摘　　要

NOVELTY - A core wire comprises a conductor (1), an inner layer (2), a foaming layer (3) and an outer layer (4). The inner layer comprises 50-60 pts. wt. low density polyethylene and 40-50 pts. wt. LD additive. The foaming layer comprises 60-75 pts. wt. crosslinked polyethylene, 26-33 pts. wt. low density polyethylene and 1.5-3 pts. wt. nucleating agent. The outer layer comprises 60-80 pts. wt. high density polyethylene and 20-40 pts. wt. low density polyethylene. USE - Core wire used for high-speed transmission line (claimed). DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for preparation of core wire comprising using three-layer co-extrusion machine to extrude the inner skin layer, foaming layer and outer skin layer on the outer side wall of the conductor for one time forming, preparing insulating layer, extruding insulating layer and conductor, and irradiating and crosslinking via electron accelerator at crosslinker dose is not more than 8 Mard. DESCRIPTION OF DRAWING(S) - The drawing shows a structural schematic diagram of the core wire. Conductor (1) Inner layer (2) Forming foaming layer (3) Outer layer (4)