Antenna impedance mismatch measurement and correction for adaptive CDMA transceivers

A tunable matching network has been developed to adaptively correct antenna impedance mismatch for CDMA transceivers. The tuning network consists of two L structures in cascade and is implemented with silicon-on-sapphire switches, fixed capacitors and inductors. Experimental results show the matching network can correct antenna impedance mismatch over a wide range. It has adequate linearity for CDMA applications and an insertion loss of 0.4 dB. A simple method has also been developed to measure the antenna load impedance based on the measurement of the envelope voltages at three points along a section of transmission line. This method is independent of input power to the antenna and source impedance seen by the antenna. This method could be integrated with the tunable matching network to correct the load impedance mismatch for an adaptive transceiver.