Patent ID: 8334619

Claim:
A frequency variable power transmitter in Fresnel region used in a frequency variable power transmitting system in Fresnel region having a capacitive element and an inductive element formed in an antenna for transmitting power by electromagnetic wave between a transmitter and a receiver in order to use static field and induction field at the same time in power transmission, setting a transmitting frequency of the transmitter to be variable, and modulating the electromagnetic wave transmitted from the transmitter and reflected by the receiver to control power transmission efficiency between the transmitter and the receiver by using the modulated reflection wave, the frequency variable power transmitter in Fresnel region comprising: the antenna; a frequency variable carrier generator; a directional coupler; a demodulator; and a control circuit, wherein the reflection wave received by the antenna is divided by the directional coupler, and then, the reflection wave is demodulated by the demodulator, and the frequency of the frequency variable carrier generator can be varied by using the demodulated signal.