Patent ID: 8750816

Claim:
A process of estimating an admittance of a radio frequency (RF) component, comprising the steps of: providing a ladder network coupled to said RF component, said ladder network including alternating series components and parallel components, in which at least one of said series components and parallel components is tunable; providing a directional coupler coupled to said ladder network opposite from said RF component; providing a signal source coupled to said directional coupler opposite from said ladder network, so that said directional coupler provides an incident signal which is related to an amplitude of an incident signal from said signal source and provides a reflected signal which is related to an amplitude of a reflected signal from said ladder network; providing an RF voltmeter configured to receive said incident signal and said reflected signal and to provide a power meter output signal; providing a processor configured to receive said power meter output signal and to adjust admittance values of said at least one tunable component in said ladder network; performing three voltage standing wave ratio (VSWR) measurements, in which each VSWR measurement includes the steps of: said processor adjusting said admittance values of said at least one tunable component of said ladder network to desired values; said signal source providing a signal at a desired frequency; said directional coupler providing an incident signal and a reflected signal to said RF voltmeter; computing a magnitude of a ratio of said reflected signal to said incident signal so as to provide a reflection coefficient magnitude value |Γ|; computing a VSWR value using said incident signal and said reflected signal according to the equation: VSWR = 1 +  Γ  1 -  Γ  ; computing a center (g c , b c ) and a radius R c of an admittance circle in a complex admittance plane at a first reference plane defined at an incident side of said ladder network, and iterating through successive reference planes defined in said ladder network and transforming said coordinates of said center and said radius of said admittance circle at each said successive reference plane, wherein each said successive reference plane is defined downstream of an immediately previous reference plane by one of said alternating series components and parallel components in said ladder network, so that a last of said reference planes is immediately upstream of said RF component and immediately downstream of said ladder network.