PURPOSE: A method for manufacturing a multistage antenna is provided to reduce a noise by integrating a sleeve made of metal materials with an elastic unit made of synthetic resin through an insert-molding. CONSTITUTION: A mold is designed by calculating the number of sleeves and the load value of an elastic unit(S1). A plurality of sleeves with each diameter is made(S2). A plurality of fixed grooves are formed in the sleeve(S3). The elastic unit is formed by insert injection molding(S4). A multistage antenna is assembled by combining the plurality of sleeves(S5).
