Method for calibration of a vectorial network analyzer having more than two ports
View Patent ↗Method for calibrating a vectorial network analyzer, with n measurement ports (n>2) and at least m measurement sites, where m>n+1 includes measurement of three different n-port reflection standards, connected between measurement ports in any desired order, and successive measurement of reflection and transmission parameters at different transmission standards, connected between two respective measurement ports, and computational determination of error coefficients and error-corrected scattering matrices [S x ] of the n-port standards. Reflection standards, Short and Open, are unknown, but physically identical at each n-fold one-port. Reflection standard, realized by wave terminations, is known, but can be different at each n-fold one-port. Transmission standards are measured at a transmission standard, having known length and attenuation at a two-port, and at unknown transmission standards, identical for incident and reflected waves at remaining two-ports, which can be connected. Unknown reflection and transmission values are determined computationally by the measurements.
1. Method for calibrating a vectorial network analyzer, which exhibits n measurement ports (n>2) and at least m measurement sites, where m>n+1, by measurements of three different n-port calibration standards, which are connected between the measurement ports in any desired order and which are not permitted to show any transmission (reflection standards), and by successive measurement of reflection and transmission parameters at k=sum(n−i) for (i=1, 2, . . . , n−1) different two-port calibration standards, which are connected between the measurement ports in any desired order and must all exhibit a transmission path (transmission standards), and by computational determination of error coefficients of the network analyzer with 10-term method in k-fold application by using the measured two-port calibration standards as well as by computational determination of error-corrected scattering matrices [S x ] of the n-port calibration standards from the error coefficients of each two-port calibration standard, taking into consideration transmission error variables of remaining n−2 measurement ports with the 10-term multiport method, wherein
a) one of the n-port calibration standards measurements carried out at an n-fold one-port (n-one-port), which is realized by n known impedances,
b) one of the n-port calibration standards measurements is a reflection standard Short carried out at an n-one-port, which is realized by n unknown, highly reflecting terminations (R=Reflect), whose electronic properties are similar to those of ideal short circuits (S=Short),
c) one of the n-port calibration standards measurements is a reflection standard Open carried out at an n-one-port, which is realized by means of n unknown, highly reflecting terminations (R=Reflect), whose electronic properties are similar to those of ideal open circuits (O=Open),
d) the reflection standards Short and Open are realized so as to be physically identical at each port,
e) reflection values of the n-one-ports for reflection standards Short and Open, are determined computationally,
f) one of the two-port calibration standards measurements is carried out at a two-port, which is realized by a short adapted line (L=line) of known length and attenuation,
g) remaining k−1 two-port calibration standards measurements are carried out at k−1 two-ports, which are realized by thru connections, whose length, attenuation and impedances are unknown and are identical for an incident and reflected wave (U=unknown, reciprocal thru connection), and
h) transmission values of the two-ports, which are realized by unknown reciprocal thru connections, are determined computationally.
2. Calibration method, as claimed in claim 1 , wherein, in step f), i calibration measurements of known length and attenuation are carried out, where 1<i<k, and the remaining k−i calibration measurements with a transmission path are carried out at k−i two-ports, which are realized by an unknown, reciprocal thru connection.
3. Method for calibrating a network analyzer, as claimed in claim 1 , wherein step a) is carried out at a one-port, and is realized by a known impedance, and properties of impedances at remaining n−1 one-ports are determined computationally from a calibration measurement of the known impedance at the one-port.
4. Method for calibrating a network analyzer, as claimed in claim 1 , wherein step a) is carried out, at an (n−i)-one-port, where i<n, which is realized by a known impedance or a plurality of known impedances, and properties of the known impedances at remaining i one-ports are determined computationally from a calibration measurement of the known impedances at the (n−i) one-ports.
5. Method for calibrating a network analyzer, as claimed in claim 1 , wherein electronic properties of one of the highly reflecting terminations are known.
6. Method for calibrating a network analyzer, as claimed in claim 1 , wherein at least two of the unknown, reciprocal thru connections are symmetrical to each other for n>3.
7. Method for calibrating a vectorial network analyzer, which exhibits n measurement ports (n>2) and at least m measurement sites, where m>n+1, by measurement of three different n-port calibration standards, which are connected between the measurement ports in any desired order and which are not permitted to show any transmission, and by successive measurement of reflection and transmission parameters at n−1 different two-port calibration standards, which are connected between the measurement ports in any desired order and must all exhibit a transmission path, and by computational determination of error coefficients of the network analyzer with 7-term method in n−1-fold application by using the measured two-port calibration standards as well as by computational determination of error-corrected scattering matrices [S x ] of the n-port calibration standards from the error coefficients of each two-port calibration standard, taking into consideration transmission error variables of the remaining n−2 measurement ports with the 7-term multiport method, wherein
a) one of the n-port calibration standards measurements is carried out at an n-one-port, which is realized by n known impedances,
b) one of the n-port calibration standards measurements is a reflection standard Short carried out at an n-one-port, which is realized by n unknown, highly reflecting terminations (R=Reflect), whose electronic properties are similar to those of ideal short circuits (S=Short),
c) one of the n-port calibration standards measurements is a reflection standard Open carried out at an n-one-port, which is realized by n unknown, highly reflecting terminations (R=Reflect), whose electronic properties are similar to those of ideal open circuits (O=Open), and
d) the reflection standards, Short and Open are realized so as to be physically identical at each port,
e) reflection values of the n-one-ports for reflection standards Short and Open are determined computationally,
f) one of the two-port calibration standards measurements is carried out at a two-port, which is realized between a measurement port, which is established as a reference measurement port, and one of the n−1 remaining ports by a short adapted line (L=line) of known length and attenuation,
g) remaining n−2 two-port calibration standards measurements are carried out at n−2 two-ports, which are realized by an unknown, reciprocal thru connection, and
h) transmission values of the two-ports, which are realized by an unknown reciprocal thru connection, are determined computationally.
8. Calibration method, as claimed in claim 7 , wherein, in step f), i calibration measurements with a transmission path of known length are carried out, where 1<i<n−1, and the remaining n−1−i calibration measurements are carried out at n−1−i two-ports, which are realized by an unknown, reciprocal thru connection.