AnsweredAssumed Answered

TRL Line Inaccuracy Problem

Question asked by asubraman on May 10, 2007
Latest reply on May 13, 2007 by Dr_joel
Hi,
I'm trying to calibrate a PNA-L NA N5230A 300KHz to 6 GHz Analyzer using a TRL Kit fabricated in house. I created the TRL Lines using FR4 board and created a Calibrate kit on the VNA. When I go to verify the kit after calibration the Line always consistantly is 10 degrees off of what it should be. The Line is supposed to be 90 degrees, but reads out as 78-80 degrees. All other standards read out correct. Here is the information about the TRL lines I created and the cal Kit.

Board: FR4
er-5.4
eeff - 3.9
thick - 62.5 mils
TanD loss - 0.035
metal thick - 17 um
freq - 2Ghz

Reflect:
W: 2.57 mm
L: 7 mm

Thru:
W: 2.57 mm
L: 14 mm

Line:
W: 2.57 mm
L: 32.766 mm

Connector: 3.5 mm SMA

CalKit:
OPEN:
Freq Range -
Min: 0 , Max = 18000 GHz
CO,C1,C2,C3= 0
Delay =0, Loss = 0, Z0= 50 ohms

THRU:
Min:0, Max=18000 GHz
Delay =0, Loss= 0, Z0 = 50

LINE:
Delay:160 pSec (computed from delay equation, but any value here seems to not affect the results i'm getting)
Loss: 0, Z0=50

Port: 3.5 mm male
Testport ref : THRU
Cal Kit: TRL THRU

If perhaps you see the errors in my ways or if anybody has a solution to this problem please let me know. Thank you!

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