An antenna system, comprising: an RF input port, wherein the RF input port is configured to receive an input RF signal, wherein the input RF signal is suitable for reading at least one RFID tag; a plurality of antennas, wherein each antenna of the plurality of antennas is configured to produce an RF field in a volume of interest when an antenna input signal is inputted to each antenna of the plurality of antennas, wherein one or more antenna of the plurality of antennas is configured to produce an RF field at any position in the volume of interest; circuitry adapted to produce a corresponding plurality of antenna input signals from the input RF signal, wherein each of the antenna input signal of the plurality of antenna input signals is suitable for reading the at least one RFID tag, wherein when the plurality of antenna input signals is simultaneously inputted to the plurality of antennas a corresponding plurality of RF fields is simultaneously produced in the volume of interest; a state controller, wherein the state controller is configured to change a state of the plurality of antennas by altering the plurality of RF fields, wherein the state controller produces a first state during a first period of time and produces a second state during a second period of time, wherein the state controller is configured to alter the plurality RF fields by altering one or more of the following: a phase of at least a first one of the plurality of antenna input signals, wherein altering the phase of said first antenna input signal of the plurality of antenna input signals is independent of altering a phase of any other antenna input signal of the plurality of antenna input signals, a ratio of amplitudes of at least two antenna input signals of the plurality of antenna input signals, a radiation pattern of at least a first antenna input signal of the plurality of antennas, and a polarization of at least a second antenna input signal of the plurality of antennas; and an RF receiver, wherein the RF receiver is configured to receive a return RF signal, wherein the return RF signal is due to the plurality of the RF fields being incident on one or more of the at least one RFID tag. an RF input port, wherein the RF input port is configured to receive an input RF signal, wherein the input RF signal is suitable for reading at least one RFID tag; a plurality of antennas, wherein each antenna of the plurality of antennas is configured to produce an RF field in a volume of interest when an antenna input signal is inputted to each antenna of the plurality of antennas, wherein one or more antenna of the plurality of antennas is configured to produce an RF field at any position in the volume of interest; circuitry adapted to produce a corresponding plurality of antenna input signals from the input RF signal, wherein each of the antenna input signal of the plurality of antenna input signals is suitable for reading the at least one RFID tag, wherein when the plurality of antenna input signals is simultaneously inputted to the plurality of antennas a corresponding plurality of RF fields is simultaneously produced in the volume of interest; a state controller, wherein the state controller is configured to change a state of the plurality of antennas by altering the plurality of RF fields, wherein the state controller produces a first state during a first period of time and produces a second state during a second period of time, wherein the state controller is configured to alter the plurality RF fields by altering one or more of the following: a phase of at least a first one of the plurality of antenna input signals, wherein altering the phase of said first antenna input signal of the plurality of antenna input signals is independent of altering a phase of any other antenna input signal of the plurality of antenna input signals, a ratio of amplitudes of at least two antenna input signals of the plurality of antenna input signals, a radiation pattern of at least a first antenna input signal of the plurality of antennas, and a polarization of at least a second antenna input signal of the plurality of antennas; and an RF receiver, wherein the RF receiver is configured to receive a return RF signal, wherein the return RF signal is due to the plurality of the RF fields being incident on one or more of the at least one RFID tag. a phase of at least a first one of the plurality of antenna input signals, wherein altering the phase of said first antenna input signal of the plurality of antenna input signals is independent of altering a phase of any other antenna input signal of the plurality of antenna input signals, a ratio of amplitudes of at least two antenna input signals of the plurality of antenna input signals, a radiation pattern of at least a first antenna input signal of the plurality of antennas, and a polarization of at least a second antenna input signal of the plurality of antennas; and an RF receiver, wherein the RF receiver is configured to receive a return RF signal, wherein the return RF signal is due to the plurality of the RF fields being incident on one or more of the at least one RFID tag.