Pengembangan Material Dielektrik Melalui Sistem Nano Komposit [BaTi(1-x)ZnxO3](1-y)-[CoFe2O4]y (x = 0; 1/3; 1/2; 2/3; 1; dan y = 0,2; 0,5; 0,8) untuk Aplikasi Penyerap Gelombang Elektromagnetik = Development of Dielectric Materials Through Nano-Composite Systems [BaTi(1-x)ZnxO3](1-y)-[CoFe2O4]y (x = 0; 1/3; 1/2; 2/3; 1; and y = 0.2 ; 0.5; 0.8) for Electromagnetic Wave Absorber Application