Adaptive Impedance Matching (AIM) For Electrically Small Radio Receiver Antennas

An apparatus, comprising:

• an antenna;
• a circuit for producing a received signal strength indication based on the received signal;
• a processor for using the received signal strength indication to produce a control voltage;
• and
• an antenna matching circuit including a capacitance controlled by the control voltage;
• wherein the processor changes the control voltage to maximize signal gain by minimizing a ratio of a change in the received signal strength indication to a change in the control voltage.

An apparatus comprising:

• means for receiving a signal on an antenna;
• means for producing a received signal strength indication based on the received signal;
• means for using the received signal strength indication to produce a control voltage;
• and
• means for using the control voltage to control a capacitance in an antenna matching circuit;
• wherein the means for using the received signal strength indication to produce a control voltage changes the control voltage to maximize signal gain by minimizing a ratio of a change in the received signal strength indication to a change in the control voltage.