Patent ID: 7421979

Claim:
An electronic fence system capable of guiding animals to return, comprising: a transmitter for generating radio frequency (RF) signals; a plurality of loop antennas, defining a boundary of a predetermined restricted area, for radiating the RF signals into space wherein the plurality of loop antennas includes at least a first loop antenna and a second loop antenna defining an internal and external boundary, respectively, of the predetermined restricted area and further wherein the first loop antenna is positioned a specified distance inside the second loop antenna; wherein the transmitter is operable to select between a plurality of functions and to generate a control command specifying at least one of vibration, high-frequency beep, vibration with high frequency beep, shock and shock intensity wherein the transmitter includes: a power switch for selectively providing and blocking power to the transmitter; an AC-DC converter for converting AC power supplied through the power switch into DC power having a predetermined level; a function select switch for selecting a desired receiver function; an electric shock level control for setting a level of an electric shock; a transmitter power level control for controlling a transmitter power level; a frequency output circuit for controlling said transmitter power level under the control of the transmitter power level control; a transmitter microprocessor for generating a plurality of control signals defining the operational state of a receiver; an antenna loop confirming lamp for indicating an antenna loop operating state; a beep selecting lamp for indicating a high-frequency beep is selected; an electric shock selecting lamp for indicating the electric shock is selected; an automatic selecting lamp for indicating automatic operation is selected; an encoder for converting the plurality of control signals received from the microprocessor into a serial data signal suitable for transmission; a modulation circuit for modulating the serial data signal produced by the encoder into the RF signals; and a loop detecting circuit operably coupled to the modulation circuit to detect a transmission loop error and for transmitting the transmission loop error to the microprocessor; and wherein the receiver receives the transmitted RF signals and the control command and initiates a stimulation based upon the control command, the receiver further including a plurality of antennas structurally arranged to define a ninety degree axial orientation relative to each other wherein the receiver is operable to determine the animal's approach to an electronic fence from any direction.