Design and Fabrication of a Microstrip Patch Antenna Using a Flexible Low‐Dielectric, Low‐Loss Substrate

This study demonstrates the development and application of a low‐loss flexible dielectric substrate for flexible microwave antennas, consisting of butyl rubber (BR) filled with amorphous fuzed silicon dioxide (SiO 2 ). The composite was manufactured using two‐roll mixing and hot pressing, resulting in a dense substrate with uniformly dispersed fillers in the BR matrix. X‐Ray diffraction structural investigation confirmed the amorphous nature. The coefficient of thermal expansion for silicon dioxide‐filled butyl rubber (BR/SiO 2 ) composite with a weight percentage of 40 was 46 × 10 −6 /K. Dielectric measurements conducted with a vector network analyzer indicated a consistent dielectric constant (≈2.7) and minimal dielectric loss (≈0.002) in the frequency range 900 MHz to 4.5 GHz, using the resonant method, affirming suitability for microwave applications. A microstrip patch antenna was constructed on the composite substrate and the reflection coefficients (S 11 ) were evaluated under bending conditions of 0°, 10°, and 20°. The strong concordance between simulated and practicalS 11 parameters has evidenced optimal performance. In this study, the BR/SiO 2 composite has been identified as a highly suitable material for conformal antenna substrates, offering crucial properties like flexibility, low dielectric loss, and thermal stability for flexible microwave and wearable electronics.