In this paper we introduce a new version of the Pursuit-Evasion problem in which the pursuer is a 2-modem which pursues an unpredictable evader in a polygonal environment. A 2-modem searcher is a wireless device whose radio signal can penetrate two walls. We will present a new cell decomposition of a given polygon P for the 2-modem searcher such that the combinatorial representation of the invisi- ble regions of the searcher remains unchanged. In other words, when the searcher moves inside a cell, no evader can move from an invisible region to an- other one without detecting by the pursuer.