Structure characteristic impedance estimator using current probe

A method for estimating a characteristic impedance of a conductive structure comprising the following steps:

• providing a current probe comprising a magnetic core having an aperture therein, a primary winding wrapped around the core, and a conductive housing surrounding the core and the primary winding;
• measuring, with a calibrated vector network analyzer (VNA), the S-parameters of the current probe while the current probe is in an open configuration wherein nothing but air occupies the aperture and the current probe is isolated from ground, and calculating an open impedance (Zop) of the current probe based on the measured open-configuration S-parameters;
• measuring, with the VNA, the S-parameters of the current probe while the current probe is in a short configuration, wherein the current probe is electrically shorted and calculating a short impedance (Zsh) of the current probe based on the measured short-configuration S-parameters;
• measuring, with the VNA, the S-parameters of the current probe while the current probe is mounted to the structure at a given position such that the structure extends through the aperture and calculating an input impedance (Zin) of the current probe based on the S-parameters which were measured while the current probe was mounted to the structure at the given position;
• calculating an estimated structure characteristic impedance (Z′mast) at the given position according to the following equation:
• Z′mast=(Zin−Zsh) (Zop−Zsh)/(Zop−Zin);
• and
• clamping an impedance-matched current probe to the structure at the given location to create a mast clamp current probe (MCCP) antenna.

A method for estimating a characteristic impedance of a rigid, conductive structure for use as a mast clamp current probe antenna (MCCP) comprising the following steps:

• a.) providing a toroidal current probe comprising an aperture;
• b.) measuring, with a two-port vector network analyzer (VNA), the S-parameters of the current probe while the current probe is in an open configuration wherein nothing but air occupies the aperture and the current probe is electrically isolated from a ground, and calculating an open impedance (Zop) of the current probe based on the measured open-configuration S-parameters;
• c.) measuring, with the VNA, the S-parameters of the current probe while the current probe is in a short configuration, wherein the current probe is electrically shorted and calculating a short impedance (Zsh) of the current probe based on the measured short-configuration S-parameters;
• d.) measuring, with the VNA, the S-parameters of the current probe while the current probe is mounted to the structure at a given position such that the structure extends through the aperture and calculating an input impedance (Zin) of the current probe based on the S-parameters which were measured while the current probe was mounted to the structure at the given position;
• e.) calculating a characteristic impedance (Z′mast) of the structure at the given location according to the following equation:
• Z′mast=(Zin−Zsh)(Zop−Zsh)/(Zop−Zin);
• f.) repeating steps (d) and (e) for each of a plurality of locations on the structure;
• and
• g.) identifying, amongst the plurality of locations, a best location having a corresponding Z′mast value that most closely matches the input impedance (Zin) of the current probe.