Design of a transparent, flexible RF membrane antenna for WBAN applications using polydimethylsiloxane (PDMS)

In this work, a flexible antenna as an Radio Frequency (RF) sensor is presented, which is used in Wireless Body Area Network communications. For on-body and off-body communications, the antenna elements have directional and quasi-omnidirectional patterns. This antenna is transparent, made from a polydimethylsiloxane (PDMS) substrate, which is well-known for its flexibility, with copper as its conducting element. The proposed design uses a PDMS substrate with a loss tangent tan δ of 0.02 and a dielectric constant ε r of 2.65. The overall size of a compact antenna is 36.98 × 29.8 × 1 mm, which provides a wide impedance bandwidth that covers the wideband spectrum. Using slots and stubs, antennas were modified as a simple geometrical configuration to achieve a flexible and compact antenna size. The presented design is simulated by CST Microwave Studio with a range of operating frequencies from 3.26 to 4.62 GHz, a bandwidth of 1.36 GHz, and a gain of 2.42 dBi in its planar form. This achieves the required compactness, backward radiation, minimization loss, and targeted frequency bands for frequency notch characteristics used in the human body of proximity.