Alarm systems, wireless alarm devices, and article security methods are described according to some aspects of the disclosure. In one aspect, an alarm system includes a base communication device configured to communicate wireless signals, a remote communication device configured to communicate with the base communication device using the wireless signals, wherein the remote communication device is adapted to be associated with an article to be secured and wherein the remote communication device comprises alarm circuitry, wherein the remote communication device comprises a non-linear device configured to detect the wireless signals communicated by the base communication device and to generate electrical signals corresponding to respective ones of the detected wireless signals, and wherein the remote communication device further comprises processing circuitry coupled with the non-linear device and configured to process the electrical signals and to control the alarm circuitry to generate a human perceptible alarm responsive to the processing.