An article of manufacture comprising: a power amplifier; a receiver amplifier; a first transmission line extending between the power amplifier and an antenna port; and a second transmission line extending between the receiver amplifier and the antenna port; characterized in that the article of manufacture further comprises: a first valve configured to change an impedance of the first transmission line, wherein the first transmission line (210, 310) includes a first transmission line segment, wherein the first valve includes a first line joined to the first transmission line at a first node and including a first line segment that is disposed along the first transmission line segment and a first switch configured to couple and decouple the first line to and from ground; and a second valve configured to change an impedance of the second transmission line, wherein the second transmission line includes a second transmission line segment, wherein the second valve includes a third line joined to the second transmission line at a second node and including a third line segment that is disposed along the second transmission line segment and a second switch configured to couple and decouple the third line to and from ground; the first and second valves being controllable such that when one is open the other is closed. a power amplifier; a receiver amplifier; a first transmission line extending between the power amplifier and an antenna port; and a second transmission line extending between the receiver amplifier and the antenna port; characterized in that the article of manufacture further comprises: a first valve configured to change an impedance of the first transmission line, wherein the first transmission line (210, 310) includes a first transmission line segment, wherein the first valve includes a first line joined to the first transmission line at a first node and including a first line segment that is disposed along the first transmission line segment and a first switch configured to couple and decouple the first line to and from ground; and a second valve configured to change an impedance of the second transmission line, wherein the second transmission line includes a second transmission line segment, wherein the second valve includes a third line joined to the second transmission line at a second node and including a third line segment that is disposed along the second transmission line segment and a second switch configured to couple and decouple the third line to and from ground; a first valve configured to change an impedance of the first transmission line, wherein the first transmission line (210, 310) includes a first transmission line segment, wherein the first valve includes a first line joined to the first transmission line at a first node and including a first line segment that is disposed along the first transmission line segment and a first switch configured to couple and decouple the first line to and from ground; and a second valve configured to change an impedance of the second transmission line, wherein the second transmission line includes a second transmission line segment, wherein the second valve includes a third line joined to the second transmission line at a second node and including a third line segment that is disposed along the second transmission line segment and a second switch configured to couple and decouple the third line to and from ground; the first and second valves being controllable such that when one is open the other is closed.