In this paper we propose a second-order harmonic-enhanced circuit design in an energy harvesting receiver. For accurate location detection, a LC resonator together with harmonic-enhanced coupler is placed after a dual-band Yagi-Uda antenna. This design helps the beamforming power transmitter to do maximum power transfer when an EH-receiver moves into the power transfer coverage region and its stored energy level is too low to provide DC power. Our measured results show the sensed second-order harmonic power level can be increased +25dB after adding the harmonic enhancement board in the proposed EH-receiver circuit. A location detection system can be achieved by a simple, convenient and useful way.