Radiation pattern anomalies in the broadband CP reconfigurable E-shaped patch antenna

The evolution of wireless communications towards wideband systems has motivated research worldwide to develop new high performance antenna designs. In particular, one class of antennas that has gained popularity are broadband CP reconfigurable patch antennas. Such antenna designs not only minimize the dependence on antenna orientation, but they also provide additional functionality for diversity and MIMO systems. Recently, an asymmetric E-shaped patch antenna was introduced as a new design candidate for wideband CP applications. This design has shown much promise in providing a wide S₁₁/AR bandwidth by introducing asymmetric slots into the E-shaped design. Polarization reconfigurable designs using MEMS switches have also been demonstrated. The typical design approach for this and other CP patch antennas optimizes the S₁₁ and the AR towards broadside. In this paper, we will show that this approach can lead to E-shaped designs with peculiar beam tilts in the pattern at upper frequencies. The direction of these beams change for RHCP/LHCP polarization states, making beam tilt compensation more difficult to achieve for all configurations. We investigate this beam tilt further to understand its origin and possible compensation techniques for single radiator and array applications [Summary form only given].