A Pneumatically Controlled Reconfigurable Antenna With Three States of Polarization

Many of the existing antennas described in current literature utilize PIN diodes to achieve switchable polarization. In realizing more elaborate reconfigurable antennas, the biasing structures for these DC-controlled components become more complex, which leads to limitations in the RF design as well as losses and undesired radiation. Other reconfigurable technologies, such as MEMS switches and liquid crystals, could be chosen for a particular application depending on various trade-offs, for example efficiency and ease of implementation. An alternative system is a recently developed scheme of using pneumatically controlled solid dielectric slugs, which is low-loss and immune to RF distortion, and eliminates the need for DC biasing structures. To demonstrate the viability of this system, it was incorporated in the design of a reconfigurable ring slot antenna capable of three polarization states (LP/LHCP/RHCP) at 2.4 GHz. The measured axial-ratio bandwidth was 5%, which is comparable to similar low-profile antennas. The simulated and measured antenna performance at all three states showed strong correlation. The pneumatic actuation of four slugs inside a channel to realize the three different states was successfully implemented, demonstrating that pneumatic slug control technology is suitable for inclusion in reconfigurable antennas.