Rectification of microwave power

Direct conversion of microwave energy into dc power is relatively new to research and development, probably because there was no need for a conversion device until its desirability was recognized in connection with power transfer by microwave beam. Lacking an efficient direct electric converter, early protagonists of microwave power transmission relied upon an approach that would first convert the microwave energy into heat, which then generated electric energy indirectly with the use of some type of heat engine. In addition to the complexity of this arrangement, the best expected overall efficiency from microwave power to dc power is well below 25 per cent.