A Frequency Reconfigurable Transmitter Antenna With Autonomous Switching Capabilities

Frequency reconfigurable antennas have many benefits that can be used to improve the performance of wireless systems. Then again, many existing multiband systems cannot use a frequency reconfigurable antenna because of the additional control signals required to operate the antenna. In this communication, an autonomous frequency reconfigurable antenna topology that does not require these control signals from the radio is presented. To control the antenna, a power splitter and bandpass filter is used to pass a portion of the RF power driving the antenna in a particular band to voltage-doubling circuitry. This voltage-doubler circuit is then used to convert the RF signal into a DC output control voltage which then in turn controls the reconfigurable features of the antenna. By setting the bandpass filter to one of the reconfigurable frequencies, RF power can then be used to reconfigure the antenna in a specific band while not reconfiguring in other bands. This flexibility makes this design very useful for existing and future cost effective wireless systems.