Browsing by Author "Wu, Billy"

Now showing 1 - 2 of 2
  • Thumbnail Image
    ItemOpen Access
    Design of mems capacitive switches for a tunable reflectarray element
    (2008) Wu, Billy; Okoniewski, Michal; Potter, Michael E.
  • Thumbnail Image
    ItemOpen Access
    Reconfigurable RF Devices Using Pneumatic Control of Solid Dielectric Slugs
    (2014-09-29) Wu, Billy; Okoniewski, Michal
    Many antennas reported with switchable polarization were designed using PIN diodes because of their reliability and commercial availability. However, in realizing more elaborate antennas, the biasing structures for these DC-controlled switching components become more complex, which leads to design limitations, losses, and undesired radiation. Other reconfigurable technologies, such as MEMS and liquid crystals, could be chosen for a particular application depending on various trade-offs, for example efficiency and ease of implementation. A recently developed scheme of using pneumatically controlled solid dielectric slugs offers an alternative to the existing technologies. These copper-backed slugs are confined within a dielectric channel adjacent to the conducting layer. A slug is either directly above or situated away from a slit in the conducting layer to realize its two switching states. Its translational movement is induced by a pneumatic pressure gradient inside the channel. The technology is low-loss and immune to RF distortion, and eliminates the need of DC biasing structures. This technique was incorporated in the design of a reconfigurable ring slot antenna capable of three polarization states (LP/LHCP/RHCP) at the 2.4-GHz ISM band. The multilayered structure consisted of low-loss dielectric laminate layers that were laser-machined to produce the precise profile and smooth edges required for repeatable movement of the slugs. The measured axial ratio (AR) bandwidth is 5%, which compares favourably to similar antennas. Parametric analyses were performed to accomplish the challenging task of realizing a design in which, the AR and impedance bandwidths of all three states shared a common frequency band centered around 2.4 GHz. An overall three-state bandwidth of 2.4% was achieved, which is the highest amongst similar antennas operating in the same frequency range. The measured antenna performance — radiation patterns, gain values, AR, and |S11| — in all three polarization states was consistent with the simulated performance. 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.