Electromagnetic performance of three-dimensional woven spacer microstrip antenna with various conductive fibers in extreme temperatures

Due to its excellent light-weight, mechanical, and electromagnetic performance, the three-dimensional woven spacer microstrip antenna (3DWS-MA) has become a promising communication device to be applied in aerospace or high-speed vehicles. To explore the electromagnetic performance of 3DWS-MA in extreme environments, microstrip antennas based on three-dimensional woven glass fiber/epoxy spacer composites (3DWSC) with different conductive yarn (copper wire, nickel-coated carbon yarn and carbon nanotube yarn) were manufactured and tested at various temperatures (from –196°C to 150°C). The results showed that the 3DWSC exhibited superb dielectric properties ([Formula: see text]) with a low volume density of 0.5 g[Formula: see text]cm ⁻³ , rendering good electromagnetic performance of the prepared antenna (S ₁₁ value of –23 dB and gain of 7 dB). When the temperature increased from –196°C to 150°C, the dielectric constant of 3DWSC increased from 1.57 to 1.67, resulting in the decrease of resonance frequency of 3DWS-MAs (maximum offset is 60 MHz). In addition, the resistance changing ratios of the conductive fibers also reached 105% with the temperature increase, resulting in degradations of S ₁₁ values (maximum 17 dB). Furthermore, among the three types of 3DWS-MAs, the 3DWS-MA (carbon nanotube yarn) exhibited the most stable S ₁₁ value at low temperatures (from –196°C to 0°C), while the 3DWS-MA (copper) showed low return loss and stable resonance frequency at high temperatures (from 20°C to 150°C).