Electronically tunable composite right/left handed transmission line for the Slotted Waveguide Antenna Stiffened Structure

The Slotted Waveguide Antenna Stiffened Structure (SWASS) utilizes conventional hat-stiffeners or blade stiffeners in aircraft sandwich structures as microwave waveguides. Slotted waveguide antenna arrays may therefore be integrated into the structure by machining slots through the outer skin. However, the primary mechanical load applied to the structure governs the orientation of these slotted waveguides and so limits electronic beam steering to just one plane. This work extends the SWASS concept by demonstrating a means to achieve electronic phase shifting along the waveguide axis. This is accomplished by incorporating a varactor loaded coaxial composite right / left handed transmission line (CRLH-TL) into the SWASS for approximate matched tuning of the dispersion diagram about the design frequency.