Exemplary systems and methods are provided for collecting/harvesting direct current (DC) power received from a power source(s). The system comprises a controlled impedance power controller comprises a power converter configured to present a positive equivalent resistive load to the at least one power source over a range of input power levels. Exemplary systems and methods are provided for collecting radio frequency (RF) power. An exemplary system comprises at least two rectenna elements, a power controller, and a DC combining circuit. The DC combining circuit is associated with the at least two rectenna elements and the DC combining circuit is configured to dynamically combine the at least two rectenna elements in one of a plurality of series/parallel configurations. The power controller is configured to control the DC combining circuit to achieve a desired overall power output from the at least two rectenna elements.