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. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 40: 402–406, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.11393