Terminator3
Advanced Member level 3
Hello all! Recently I have seen few designs where rat-race power divider is used without 50-ohm termination. Instead there was a tiny open stub, around lambda/8 or less. I tried to simulate such coupler with open stub length varying from 0 to lambda/2, but no any practical usable performance was observed.
Rat-race coupler was the same as:
https://www.microwaves101.com/encyclopedias/rat-race-couplers
Rat-race coupler (equal power split), port 3 is terminated with resistor (50 Ohm to ground or RF quarterwave-stub ground). With resistor, even mismatched value of 20 Ohm provided acceptable performance.
What is the purpose of tiny stub instead of resistor? Why i did not get any acceptable performance when trying to analyze similar design?
Rat-race coupler was the same as:
https://www.microwaves101.com/encyclopedias/rat-race-couplers
Rat-race coupler (equal power split), port 3 is terminated with resistor (50 Ohm to ground or RF quarterwave-stub ground). With resistor, even mismatched value of 20 Ohm provided acceptable performance.
What is the purpose of tiny stub instead of resistor? Why i did not get any acceptable performance when trying to analyze similar design?