Mismatch correction in RF attenuation measurement using precision airlines

The RF attenuation measurement technique with a small mismatch uncertainty [3] is improved to extend the frequency effectiveness. Three additional substitution loss measurements to the variable attenuator in different phases are realized by using precision airlines of arbitrary lengths where the phase shifts are known. As a result, attenuation measurements of arbitrary frequencies could be also obtained simply without source and load matched to the line impedance. Experimental results on a 10-dB and 20-dB at 11 GHz show good agreement with measurements where the source and load are matched.