In practice, it may not be possible or convenient to control the position of the stub, as…

In practice, it may not be possible or convenient to control the position  of the stub, as required for single stub matching of a load admittance  to a line having characteristic admittance . In that case, a “double stub” matching approach can be used, where two stubs at arbitrary locations but with adjustable lengths are used. At the price of restricting the range of loads that can be matched, suppose that the first stub is attached in parallel with the load and shorted at length , and that the second stub is shorted at length  and connected in parallel with the line at a given distance  from the load. The stubs have the same characteristic admittance as the line. Describe how, given the load admittance and the distance l to the second stub, the lengths  and  would be designed to match the load to the line.