EEVblog Electronics Community Forum
Electronics => RF, Microwave, Ham Radio => Topic started by: e.sotillet on September 28, 2021, 01:31:57 pm
-
Hi folks
Right now I'm working with a board that has a bidirectional amplifier: one for 172MHz and other for 152MHz. The initial designer not take in account to make a good in-out matching to 50ohm, so i need to add a matching network (in an external board) that can be operative in both frequencies.
I tried with the usual LC network but it worked for only one frequency. I used the VNA to measure the impedance and I got he follow results:
** 119 \$\Omega\$ - j13 @ 152MHz
** 36,8 \$\Omega\$ - j50 @ 172MHz
What kind of method can I use to make the impedance adaptation to 50 \$\Omega\$ ?
Best regards
-
Hi
Try my ImpedanceMatching (https://www-ur5ffr-com.translate.goog/viewtopic.php?f=12&t=256&_x_tr_sch=http&_x_tr_sl=ru&_x_tr_tl=en&_x_tr_hl=uk&_x_tr_pto=nui) free software. Some results for your case in attachment
-
Hi Andrey, thanks a lot. I will test and comment the results.
Best regards
-
As attachment is the measurement of the builded adapter, I think it could be improved a lil bit.
-
What circuit did you use in the adapter?
-
I used the option 3, with air coils and variable capacitors. The adjustment with the VNA help alot.
I think that the improvement will come putting everything in a PCB.
In the other hand, using smd inductor instead of air coil can degrade the behaivor?
Best regards