[Help-gnucap] (no subject)

[Karl Hammar]

 Hello,

I get different volt calculated vs. measured in node 2 of
simulation below. Can anyone point to where my mistake is?

It should be 0.5 V for 50 Ohm input impedance but only measures
to less than 200 mV. Replacing circuit 50 Ohm BNC terminator gives me
the correct 500mV.

My stuff is available in:

 http://turkos.aspodata.se/git/openhw/rfid/

the schematics and pcb files are in a flux currently.

///

$ cat Todo/antenna_simulation.ckt 
antenna_simulation

V1   1 0 generator(1) ac 1
Ro   1 2 50
C1a  2 4 7.39e-10
C1b  0 3 7.39e-10
C2   2 0 1.65e-09
Cpar 4 3 1e-11
L    4 3 4.4e-07
Rpar 4 3 1500

.option nopage
.print ac I(L) V(2)
.AC 12.5Meg 14.5Meg 10k > Todo/antenna_simulation.dat
.end
$

I can calculate resonane, upper and lower 3dB points and Q

     MHz    I(L)     V(2)
f1:  13.220 0.052022 0.26108
max: 13.560 0.073039 0.49553
f2:  13.900 0.051076 0.43503
Q = 19.9

and I can verifies ok with a loop probe, except that the V(2) comes out
at < 200 mV.

More details in are available in antenna_simulation.readme.

Regards,
/Karl Hammar

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