The ac properties of random barrier network are analyzed using the effective medium theory.At low frequencies om -cus and a t high frequencies i t saturates to the value determined by the conductivity of the bulk material. Below the percolation threshold s N 0.8, a t the threshold s zz 0.4, and above the threshold s still decreases. The effective dielectric constant P, decreases with increasing frequency saturating to the bulk value a t high frequencies. At, the percolation threshold em shows a pronounced maximum exceeding by several orders of magnitude the bulk value.Die Wechselstromeigenschaften des Random-Barrieren-Netzwerks werden mittels der Effektiv-