An in vitro exposure system, based on a Wire Patch Cell (WPC) and operating in the whole band of the Wi-Fi signal, has been fabricated and characterized. The system enables the contemporary exposure of four 35 mm Petri dishes and can be inserted into a commercial incubator. Results of both simulations and measurements indicate a good behavior in the band. The mean efficiency, in terms of Specific Absorption Rate (SAR) in the biological sample for 1 W of input power, is higher than 0.75 (W/kg)/W. The homogeneity of the SAR distribution inside each Petri dish is above 70 % in the lowest layer of the biological solution, indicating the optimal employment of the system for the exposure of cell monolayers. © 2010 IEEE.