U-shaped harmonic rejection filtenna for compact rectenna application

A novel compact proximity coupled microstrip antenna with harmonic rejection for a 2.45GHz rectenna application is presented. A square ring slot has been fit at the ground structure for compactness, resulting in a 46% reduction of patch element area as compared to conventional designs. The evolution of the filter structure began with a U-slot followed by a pair of inverted U-stubs created on the transmission line. Adequate suppression of the 2^nd and 3^rd harmonics are obtained with minimum reflection coefficients of −3.1 dB and −0.9 dB respectively. The simulation and measurement results show a good agreement with respect to reflection coefficient performance.