Hi Martin,
Also I noticed that schematic diagram of Biastee's having presented the loop antenna as a dummy load in order to run S21 test with VNA.
In my opinion, the layout should be changed differently:
1. Yes, between CH0 port of VNA shall be a fixed attenuator, say for 20 - 60 dB. However, it shall be Pi configured for balanced connection with a shunt arm - active resistor of value 2 ohms ( that resistor would represent the loss of antenna ).
--- |--------^^^^^---|------~~~~~~~~~~~~~~~~|----------->
R1=50 ohm R3 R2=2 ohm L1=700 nH = Ca<50 pF to amp under test
|--------^^^^^---|------~~~~~~~~~~~~~~~|------------>
GND R3=R4=10 ohm - 3Kohm L2=700 nH
2. Connect L1=L2=700 nH as series arms and an additional shunt arm with capacitor Ca<50 pF
3. The LPF might be connected as well as based on actual situation FMBS interferers.
Regards,
Raphael
