Calibrating Broadband Highly Mismatched Noise Sources

Two methods are presented for calibrating broadband highly mismatched noise sources. The first is a reformulation and an extension of the procedure used for very accurately calibrating matched noise sources. It uses isolators and works whatever the source reflection factor. With the second method, the excess noise ratio of the noise source is numerically optimized until the measured reverse noise wave of an attenuator is equal to the theoretical value derived from its S-parameters. It can be applied to sources with reflection factors of about 0.45 to 0.90. Both methods appear to give very consistent results.