Main beam deflection and gain enhancement in superstrate-based antenna systems

The beam of an antenna can be controlled by placing high refractive index superstrates. In this paper, a plane-wave model of a microstrip antenna covered with a high refractive index is introduced. The antenna-superstrate system is analyzed by calculating its transmission response. When the patch is fully covered with the superstrate, the transmission response is truncated along the end-fire angles resulting in gain enhancement. On the other hand, when the superstrate partially covers the patch, a phase imbalance between the electromagnetic radiations emitted from the two radiating slots is produced. This imbalance causes the main beam to deflect from the broadside direction. Full-wave and plane-wave simulations show beam deflections close to 40 degrees. Tunable superstrates can thus be applied to steer the beam of a patch. Hence a novel method is introduced which has been traditionally done using multiple antenna elements with phase shifters.