Theoretical and experimental study on rectenna array for microwave power transmission

In using the rectenna array as a receiving antenna in microwave power transmission it is necessary to prevent spurious radiation of higher harmonics and from interfering with wireless communication paths and to achieve high efficiency in conversion of microwaves to dc energy. In this paper the conversion efficiency and spurious radiation of higher harmonics are examined by solving circuit equations which are transformed to difference equations with the use of Newton's method. The input impedance of the antenna is obtained by assuming an infinite planar array on a perfectly conducting plane. Consistent with the theoretical analysis, an experimental rectenna array is constructed and its performance is confirmed experimentally. The rectenna array is fabricated by mounting the diode and other components in a thin-film LC circuit with soda-glass substrate using MIC technology and by connecting it to a 69-element half wave dipole array above an aluminum sheet.