Abstract: A radio frequency identification (RFID) tag antenna system includes a planar two arm logarithmic spiral antenna with a suitably small form factor. There are two arms are of conductive foils or etched copper plating on a substrate the extend outwardly from a center in a logarithmic fashion. The two arms are identical to each other but rotated in the plane by 180 degrees. The arms also grow proportionally in width as they extend outward, but at any given distance from the center the width of both arms are equal to each other and, preferably, equal to the spaces between the arms. An impedance matching network receives the RF signal received by the dual spiral antenna and feed the RF signal to an electronic circuit that rectifies and multiplies the signal to form a DC signal that charges a capacitor.

Abstract: For measuring characteristics (resistance, capacitance, and foreign voltage) on a telephone line, source voltages are coupled via source resistances to the line in three test conditions and the parameters are calculated from steady state voltages at the terminals of the line. Each steady state voltage is predictively calculated from nine samples of the voltage at the terminal using a closed form second order solution of a circuit model of the telephone line derived from a transformation of the circuit model into the Z domain and using the matched pole-zero technique. The steady state voltages can thus be determined without waiting for transients, due to the time constants of the telephone line, to die out, resulting in much faster measurements for telephone lines with large time constants.

Abstract: For measuring characteristics (resistance, capacitance, and foreign voltage) on a telephone line, source voltages are coupled via source resistances to the line in three test conditions and the parameters are calculated from steady state voltages at the terminals of the line. Each steady state voltage is predictively calculated from nine samples of the voltage at the terminal using a closed form second order solution of a circuit model of the telephone line derived from a transformation of the circuit model into the Z domain and using the matched pole-zero technique. The steady state voltages can thus be determined without waiting for transients, due to the time constants of the telephone line, to die out, resulting in much faster measurements for telephone lines with large time constants.