Introduction to Parallel Matching **new** 2003/06/12 15:41:01.063 GMT-5 2003/06/12 16:59:19.466 GMT-5 Bill Wilson wlw@rice.edu Bill Wilson wlw@rice.edu Elizabeth Gregory lizzardg@rice.edu Jeffrey Silverman jsilv@rice.edu An introduction to using the Smith Chart to perform matching in parallel. Let's start with the load. With the same 25 Ω resistor for the load, and plot its admittance Y L Y 0 2 . If we start moving away from the load towards the generator, in about 0.10 λ we again run into the circle which represents Y s Y 0 1 . This is such an important circle is has gained its own name, and it is frequently called the matching circle .

Getting to the Matching Circle

Note that to find out how far we had to move, we had to start at relative position 0.25 λ as our zero, or reference location. Point "B" seems to be at about 0.35 λ on the scale, and since we started at 0.25 λ , the distance is 0.35 0.25 0.10 . At "B", Y s Y 0 -1.00.7 . Thus, if we add a susceptance B with a value of 0.014 Ω -1 we would again match the line. Positive susceptance comes from a capacitor as well, and so shows how we match.

Matching With a Shunt Capacitor

Note that we are not required to go to point "B". Any point on the matching circle that we can get to is fair game. Another such point is "C" in . This is at a distance of about 0.40 λ from the load. At "C", Y s Y 0 1.00.7 and so we would put in an inductor, with a susceptance 1 ω L 0.014 Ω -1 .

Matching With a Shunt Inductor