How Trl*/Lrm* Calibration Works; Trl Error Model; Hp 8719D/20D/22D Functional Block Diagram For A 2-Port Error-Corrected - Agilent Technologies 8719D User Manual

TRL Terminology
Notice that the letters TRL, LRL, LRM, etc. are often interchanged, depending on the
standards used. For example, "LRL" indicates that two lines and a reflect standard are used;
"TRM" indicates that a thru, reflection and match standards are used. All of these refer to the
same basic method.

How TRL*/LRM* Calibration Works

The TRL*/LRM* calibration used in the HP 8719D/20D/22D relies on the characteristic
impedance of simple transmission lines rather than on a set of discrete impedance standards.
Since transmission lines are relatively easy to fabricate (in a microstrip, for example), the
impedance of these lines can be determined from the physical dimensions and substrate's
dielectric constant.
For an HP 8719D/20D/22D TRL* 2-port calibration, a total of 10 measurements are made
to quantify eight unknowns (not including the two isolation error terms). Assume the two
transmission leakage terms, EXF and EXR, are measured using the conventional technique. The
eight TRL* error terms are represented by the error adapters shown in Figure 6-52. Although
this error model is slightly different from the traditional Full 2-port 12-term model, the
conventional error terms may be derived from it. For example, the forward reflection tracking
eight unknown TlU* error terms, eight linearly independent equations are required.
The first step in the TRL* 2-port calibration process is the same as the transmission step for
a Full 2-port calibration. For the thru step, the test ports are connected together directly
(zero length thru) or with a short length of transmission line (non- zero length thru) and the
transmission frequency response and port match are measured in both directions by measuring
all four S-parameters.
Application and Operation Concepts
8 Error Terms
Figure 6-53.
error-corrected measurement& system.