DIELECTRIC SUBSTANCE FOR PLANER ANTENNA AND PLANER ANTENNA INCORPORATING IT

PURPOSE:To reduce the dielectric loss of a planer antenna and to improve the resolution of a video image by employing a single board of a polypropylene foamed body whose foaming expansion rate is a specific value or a laminated board of a polypropylene foamed body. CONSTITUTION:A single board of a polypropylene foamed body or a laminated board laminated with plural polypropylene foamed bodies whose foaming expansion rate is 1.5-7.0 is employed to obtain a planer antenna dielectric body and it is integrated to constitute the planer antenna. A polypropylene foamed body used for a raw material for the single board or the laminated board is made from a polypropylene single polymer and an ethylene-polypropylene copolymer whose ethylene content is 1-15wt.% and its foaming expansion rate is 1.5-7.0. Thus, the dielectric loss is reduced, the dispersion in the distribution of the dielectric constant within a plane is less, the surface is smooth, the dispersion of the thickness in the plane is decreased, the dielectric loss in a GHz band is reduced and then the sensitivity of the antenna is enhanced more than that of a conventional antenna.