Reconfigurable Microstrip Patch Antennas on Flexible Substrates: A design method

This article elaborates on the general design route of stretchable microstrip patch antennas, which are fabricated on polydimethylsiloxane (PDMS) soft substrates. Compared to conventional counterparts on rigid substrates, the stretchability brings about the change of both the overall physical dimensions and the electrical parameters of the materials. Being different from the traditional design route, the deformation parameters are involved into the classical design equations of the microstrip patch antenna. Based on the improved equations, the reconfigurable antenna is able to work at multiple frequency points by using a comprehensive optimization algorithm. For demonstrative purpose, a microstrip patch antenna on PDMS is designed, fabricated, and measured. The demonstrative patch antenna shows nearly the same electrical performance as expected from finite-element method modeling when the center operating frequency is tuned from 6 to 4.9 GHz under a strain of up to 20%. Compared with the simulated results of a conventional design with strain of 5% to 20%, the realized gains have increased by 0.9 dBi (0% strain at 6 GHz), 0.9 dBi (5% strain at 5.7 GHz), 1.9 dBi (15% strain at 5.2 GHz), and 0.8 dBi (20% strain at 4.9 GHz), respectively, by using the strain domain involved design method.