An example method is provided for detecting and classifying foreign objects, performed at a computer system having one or more processors and memory storing one or more programs configured for execution by the one or more processors. The method includes obtaining a plurality of electrical measurements while a wireless-power-transmitting antenna is transmitting different power beacons. The method also includes forming a feature vector according to the plurality of electrical measurements. The method further includes detecting a presence of one or more foreign objects prior to transmitting wireless power to one or more wireless power receivers by inputting the feature vector to trained one or more classifiers, wherein each classifier is a machine-learning model trained to detect foreign objects distinct from the one or more wireless power receivers.