Atek HP 8753D, User Manual, Page: 356 / 677

The TRL Calibration Procedure
Requirements for TRL Standards
When building a set of TRL standards for a microstrip or xture environment, the requirements
for each of these standard types must be satised.
Types Requirements
THRU (Zero
length)
No loss . Characteristic impedance (Z
0
) need not be known.
S
21
= S
12
= 1
6
0
S
11
= S
22
= 0
THRU
(Non-zero
length)
Z
0
of the thru must be the same as the line . (If they are not the same , the
average impedance is used.)
Attenuation of the thru need not be known.
If the thru is used to set the reference plane , the insertion phase or
electrical length must be well-known and specied. If a non-zero length
thru is specied to have zero delay , the reference plane is established in the
middle of the thru.
REFLECT Reection coecient (0 ) magnitude is optimally 1.0, but need not be
known.
Phase of 0 must known and specied to within 6 1/4 wavelength or 6 90 .
During computation of the error model, the root choice in the solution of a
quadratic equation is based on the reection data. An error in denition
would show up as a 180 error in the measured phase .
0 must be identical on both ports .
If the reect is used to set the reference plane , the phase response must be
well-known and specied.
LINE/MA TCH
(LINE)
Z
0
of the line establishes the reference impedance of the measurement
(i.e . S
11
= S
22
= 0). The calibration impedance is dened to be the same as
Z
0
of the line . If the Z
0
is known but not the desired value (i.e ., not equal to
50 ), the SYSTEMS Z
0
selection under the TRL/LRM options menu is used.
Insertion phase of the line must not be the same as the thru (zero length
or non-zero length). The dierence between the thru and line must be
between (20 and 160 ) 6 n x 180 . Measurement uncertainty will increase
signicantly when the insertion phase nears 0 or an integer multiple of 180 .
Optimal line length is 1/4 wavelength or 90 of insertion phase relative to
the thru at the middle of the desired frequency span.
Usable bandwidth for a single thru/line pair is 8:1 (frequency span:start
frequency).
Multiple thru/line pairs (Z
0
assumed identical) can be used to extend the
bandwidth to the extent transmission lines are available .
Attenuation of the line need not be known.
Insertion phase must be known and specied within
6 1/4 wavelength or 6 90 .
LINE/MA TCH
(MA TCH)
Z
0
of the match establishes the reference impedance of the measurement.
0 must be identical on both ports .
6-90 Application and Operation Concepts