Kenneth T Holt

US Patent:

6486679, Nov 26, 2002

Filed:

Jan 21, 2002

Appl. No.:

09/683574

Inventors:

Kenneth David Holt - Dallas TX 75248

International Classification:

G01R 2702

US Classification:

324610, 324706

Abstract:

A radio frequency bridge, useful for measuring complex values of an unknown impedance or associated complex reflection coefficient and VSWR value, which comprises an rf source, a novel asymmetrical bridge, a measuring device (comprising two logarithmic amplifiers, a difference amplifier and a phase detector), a computing device and a display or interface device. The complex impedance may be any two terminals of a general N-port network not to exclude an antenna with or without feed-line. The invention is more accurate than prior art when measuring complex impedance values having magnitudes from approximately five ohms to an upper value limited only by the dynamic range of the logarithmic amplifiers, normally greater than 4000 ohms. It has the great advantage of maintaining constant measuring accuracy over a wide measuring range and can be designed to operate over very wide bandwidths.