A Conformal, Dynamic Pattern-Reconfigurable Antenna Using Conductive Textile-Polymer Composite

A conformal antenna with electronically tuning capability of its radiation pattern between broadside and monopole-like patterns is proposed. The antenna is based on a proximity-fed circular patch, loaded with a ring patch and four rectangular slots. The design is planar without any use of rigid shorting posts or a complex feeding network. The reconfigurability is achieved by activating and deactivating the slots using p-i-n diodes to switch between TM02 (monopole-like mode) and perturbed TM02 distributions (broadside mode) of the antenna. For conformability, the antenna is fabricated using a highly flexible PDMS-conductive fabric composite. All the antenna parts, including the RF switches, wires, and dc biasing circuit, are fully encapsulated by PDMS to provide resilience against deformation and harsh environment. Investigations on the RF performance and mechanical stability of the antenna were conducted. Under various bendings, it was demonstrated that all the antenna components, including those for electronic switching, remained intact and in working order even under the radius bending of 40 mm, thus maintaining good pattern reconfigurability and overall performance. When bent, the measured results at 5.2 GHz show a stable radiation performance relative to those of the flat case (i.e., the maximum gain of 2.9 dBi and the efficiency of 64% in the broadside mode, corresponding to 1.75 dBi and 52% in the monopole-like mode). To the best of our knowledge, all these features have never been demonstrated in previously published pattern reconfigurable antennas.