Reflection mode phase shifter

Abstract

The invention is a mechanically or electro-mechanically driven phase shifter for radio frequencies. It is a device for phase shifting a signal propagating through a transmission line by moving a conductive construct between an active line and a ground plane of the transmission line. The conductive construct capacitively couples with either the active line and/or the ground plane, forming a capacitive shunt that reflects a significant part of the signal. The remaining portion of the signal is reflected at a terminated end of the transmission line, resulting in substantially no signal loss. The reflectance of the conductive constructs is determined by its capacitance to active line and ground, by its length, and by the step in the field-distribution at the interface between air-suspended and sledge-suspended sections. Design alterations are possible that enhance one or several of these effects, such as capacitance enhancement by dielectric coating of the sledge, any length variation, multiple sledge structures, modifications of the sledge cross-section etc. Further, a restriction to usage of only one sledge is also possible. A common driving mechanism is used when using multiple conductive constructs. The phase shifter is used in conjunction with signal separation circuits that separate incoming and reflected outgoing signals.