Available Technologies

Background

Conventional waveguide phase shifters using constricted sections, such as those disclosed in the Japanese Utility Model Appl. Publication no. 1992-123602, have simple structures but provide a fixed phase shift. As a result, they cannot be externally controlled to vary the phase shift, presenting a limitation in tunability.

Description and Advantages

To address this challenge, researchers at Kyoto University developed a variable phase shifter by introducing a movable metal plate into the waveguide, as illustrated below. The plate moves only along the direction parallel to the narrow side of the waveguide and can be positioned externally. When the plate covers a length L, it effectively increases the broad side dimension of the waveguide to a + Δa in that region, thereby altering the guided wavelength λg. This change enables adjustable phase control of the signal between Port 1 and Port 2.

　

This invention provides three main advantages:

 

⮚ Simple Structure
In this phase shifter, the phase difference can be easily and quickly adjusted by moving the movable plate relative to the main body.

　

⮚ 360-Degree Phase Range
A single unit of this phase shifter can provide any desired phase difference.

　

⮚ Low Insertion Loss
While conventional waveguide phase shifters have an insertion loss of approximately 0.3 dB, this phase shifter maintains an insertion loss of less than 0.2 dB.