An antenna includes an array of telescoping elements connected to and by a conductive disk that feeds a signal to the elements from a matching circuit within a body section. The encapsulator objects expose native interfaces that may be interrogated to discover the foreign object definition information they encapsulate. Alternatively, the stimulation therapy may be a plurality of sub-threshold stimulation pulses delivered to capture AV node vagal innervations following the detection of atrial fibrillation.