Spatial phase shifter for reflect array (circular polarisation) applications

This paper demonstrates how a rotating dipole inside a circular waveguide positioned at a distance of λg/4 from a short circuit can perform the function of a spatial phase shifter for reflect array applications. The analysis and measurement were carried out in the X-band frequency range. The resonance of the dipole is around 10.3 GHz in free space. The measured results are well matched to those simulated, and show that the reflected phase from a dipole oriented at angle φ follows closely the trend of 2φ reflected angle for linear as well as circularly polarised waves. This type of dipole phase shifter permits right hand CP to be re-reflected as right hand CP with up to 360 degree of phase modulation per element applied, thereby permitting beam steering at very low cost, and with high aperture efficiency.