GB1330016A - Procedure for automatic impedance matching and device for imple mentation of the procedure - Google Patents

Abstract

1330016 R.F. couplings SATT ELEKTRONIK AB 19 April 1971 [25 March 1970] 25284/71 Heading H4A A transforming network for matching an energy source to a load impedance comprises continuously variable reactive components which are adjusted automatically during use in accordance with detected values of the magnitude and phase angle of the transformed load impedance. In the invention, the energy source is briefly disconnected from the transforming network, when checks are made to confirm that the source is alive, and that energy flow in the network has ceased, and only then are controllers for varying the reactive components switched on. As described, a radio transmitter 4 is coupled to an aerial 5 through a contact 7 of a relay 8, a detector 6, and a transforming network which comprises a variable capacitor C and a variable inductor L. The detector 6 senses the values of the magnitude and the phase angle of the transformed load impedance, and it feeds signals representative thereof to a three-stage servo amplifier 2. When contacts 13 of a relay 12 are closed, the last stage of the servo amplifier provides control pulses for electric motors M1, M2 which control the variable inductor L and the variable capacitor C. A blocking unit 3 comprises the relay 8, a relay control circuit 10, a transmission detector 9, and a logic circuit 11. The relay control circuit 10 is fed from the intermediate stage of the servo amplifier, and it provides an output to the relay 8 (for briefly opening the contact 7) and it is connected to the logic circuit 11 (for checking the absence of power in the aerial circuit during said brief opening). The logic circuit 11 is also connected to the transmission detector 9, and it controls the operation of the relay 12. A connection is made from the intermediate stage of the servo amplifier 2 to the logic circuit 11, so that the time taken to effect matching may be monitored. If said time exceeds a predetermined value (as might occur if the aerial had been damaged) the matching attempt is interrupted.