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Additional remarks

Sonic addtional remarks about single stub matching arc set out below.

•    We notę that the procedurę described above yields two separate Solutions, of which we have only developed one, for the matching problem. There is no simple rule for preferring one solution to the other.

•    One of the nice features of single stub matching is that the procedurę always works, because wherever on the Smith Chart the normalised load admittance yt.lies, an intersection with the g = 1 circle is guaranteed when we move from that normalised admittance yL at constant radius around the chart. In fact two such interesections always occur.

•    In the above illustration of single stub matching, we havc assumed that the linę to the left of the reference piane D, the stub linę of length s and the linę of length 1 connected to the load, all have the same charactreistic admittance Yo. In a morę generał matching problem, the three lines jut mentioned can havc different characteristic

admittances. Obvious adjustments to the procedurę must then be madę.

Principally, these adjustments consist of transforming un-normalised admittances to normalised admittances or vice versa when one moves from a transmission linę of one characteristic impedance to a transmission linę of another characteristic impcdance, because it is the un-normalised admittances which always add at a junction. but the normalisd admittances only do so when the normalising admittances havc a common value.

•    The fact that the procedurę always works stands in contrast to the double stub matching method to be discussed in the next section, which works, in its simplest form, for somc load admittances but not forothers. As we will sec, howcver, the adoption of a morę complex form of double stub matching provides a cure for that problem.