A wireless communications system (200, 400), comprising: an antenna (202, 402, 540) for inputting electromagnetic signals to a receiver system (240, 530) through an antenna feedpoint (204, 404); a control system (210, 520) that calculates, in real-time, a complex value of an input impedance of the antenna (202, 402, 540) at the antenna feedpoint (204, 404), using power level measurements through a low noise amplifier (244, 430, 534) in the receiver system (240, 530) to match a load in a receiver system, wherein the power levels detected are input to the control system 210 to calculate said complex value of the input impedance of the antenna; a matching network (242, 410, 532) that is tunable by the control system to match at the antenna feedpoint (204, 404) the calculated values of the input impedance of the antenna (202, 402, 540); and a digital-to-analog converter that converts the input impedance of the antenna (202, 402, 540) to a number of voltage values that tune the matching network (242, 410, 532); wherein the control system (210, 520) comprises: computer executable program code for calculating the complex values of the input impedance; a controller configured to execute the computer executable program code that calculates values of the input impedance; and a non-linear optimizer that converges to an actual value of the input impedance of the antenna (202, 402, 540) at a quadratic rate of convergence; wherein the non-linear optimizer receives the power level measurements comprising a reference received power value, a first received power value, and a second received power value to determine a reflection coefficient of the antenna (202. 402, 540); wherein the first received power value is the power measured of the receiver system (240, 530) after a first perturbation of a number of reactive elements in the matching network (242, 410, 532); and wherein the second received power value is the power measured from the receiver system (240, 530) after a second perturbation of a number of reactive elements in the matching network, wherein a first perturbation is different from the second perturbation; further wherein the controller converts the determined reflection coefficient of the antenna to the input impedance of the antenna. an antenna (202, 402, 540) for inputting electromagnetic signals to a receiver system (240, 530) through an antenna feedpoint (204, 404); a control system (210, 520) that calculates, in real-time, a complex value of an input impedance of the antenna (202, 402, 540) at the antenna feedpoint (204, 404), using power level measurements through a low noise amplifier (244, 430, 534) in the receiver system (240, 530) to match a load in a receiver system, wherein the power levels detected are input to the control system 210 to calculate said complex value of the input impedance of the antenna; a matching network (242, 410, 532) that is tunable by the control system to match at the antenna feedpoint (204, 404) the calculated values of the input impedance of the antenna (202, 402, 540); and a digital-to-analog converter that converts the input impedance of the antenna (202, 402, 540) to a number of voltage values that tune the matching network (242, 410, 532); computer executable program code for calculating the complex values of the input impedance; a controller configured to execute the computer executable program code that calculates values of the input impedance; and a non-linear optimizer that converges to an actual value of the input impedance of the antenna (202, 402, 540) at a quadratic rate of convergence; wherein the non-linear optimizer receives the power level measurements comprising a reference received power value, a first received power value, and a second received power value to determine a reflection coefficient of the antenna (202. 402, 540); wherein the first received power value is the power measured of the receiver system (240, 530) after a first perturbation of a number of reactive elements in the matching network (242, 410, 532); and wherein the second received power value is the power measured from the receiver system (240, 530) after a second perturbation of a number of reactive elements in the matching network, wherein a first perturbation is different from the second perturbation; further wherein the controller converts the determined reflection coefficient of the antenna to the input impedance of the antenna.