A Balun for dividing an input electrical signal wherein the width of at least one of the input line, slotline and output line varies over the length

摘要

A balun for dividing an input electrical signal to produce first and second output electrical signals which are substantially out of phase, the balun including: an input port 12 for receiving the input electrical signal; an input line 14 for coupling the input electrical signal to a slotline 18; and an output line 24 for coupling the first and second output electrical signals to, respectively a first output port 26 and a second output port 28, the output line having a junction with the slotline; wherein the slotline couples the input electrical signal to the junction, and the junction acts as a divider to produce the first and second electrical signals; in which at least one of the input line, slotline and output line has a width and a length wherein the width varies over the length. By varying the width of one or more of the input line, slotline, output line, such as by steps or tapering, it is possible to vary the impedance along the length of the signal transmission track. In this way, the impedance of the transmission track can be tuned so as to obtain a wideband input match.