A network node for a wireless communication network, in particular for a wireless sensor network, includes a wireless communication device operable in a first communication mode in which the communication device emits; with a first transmit power, first communication signals for contactless communication with other network nodes in the communication network. The communication device is further operable in a second communication mode, in which the communication device emits, with a second transmit power, second communication signals for communication with a transponder, whereby the second transmit power is greater than the first transmit power. In the first communication mode, by the communication device there is detectable the presence of a transponder in the environment of the network node by the first communication signals.