(a) square membrane; (b) rectangular membrane; (c) tent membrane

⇒ TX and RX efficiency higher in tent or rectangular shaped membrane than square membrane

• TX tent membrane (46% increase); TX rectangular membrane (44%)
• RX tent membrane (43% increase); RX rectangular membrane (65%)
• Note: fewer sub-cells than square membrane could lead to more sensitivity to fabrication-induced defects

performance improvement proportional to gap and maximum deflection

⇒ rectangular membrane had the highest FBW

⇒ tent membrane had the slowest high frequency cut-off

• tent membrane composition can be seen as small square membranes put together by sharing edges

• each membrane has different boundary conditions and slightly different resonant frequencies

  

• (c) tent membrane has two peaks in impedance curve

  ⇒ due to different boundary conditions of membrane at edge and at center:

  membrane edge is stiffer, less deflection, higher resonant frequency than center

  ⇒ percentage of membrane area on edges is smaller (compared to center)

  membrane edge has less transduction efficiency, lower peak in impedance curve