An electronically controlled transmission-line phase shifter

An investigation of a microstrip transmission line in which a measure of electronic control over the wave propagation constant can be achieved is presented. The microstrip line is constructed with an adjustable-width upper plate, obtained by placing a DC bias across the p(+) and n(+) strips in doped silicon. A change in the forward-voltage bias across the silicon strip changes the current amplitude, which in turn affects a change in the conductivity of the silicon. This change in the conductivity of the silicon semiconductor produces a change in the effective width of the microstrip line, thus producing a phase shift in a high-frequency signal propagating in the line. An electronically controlled transmission line (ECTL) has applications as a feed line for a traveling wave-array antenna. (C) 2004 Wiley Periodicals, Inc.