Circularly Polarized HTS Microstrip Antenna Array

One of the important application directions of high temperature superconductor is on microwave devices. Small size and high efficiency can be gained in microstrip antenna an array by using high temperature superconducting thin film instead of normal metal, but problems such as difficult feeding and narrow band will come out.First, two usual analysis methods of the microstrip antenna are modified, which makes them more suitable for the analysis of high temperature superconductor (HTS)microstrip antennas, the characteristics of the HTS microstrip antenna different from that of their normal counterparts are analyzed and studied with these two modified methods, which include the resonant property of the HTS microstrip antenna and the effects of substrate property, the nonlinear property of high-temperature superconductors.The major disadvantage of HTS microstrop antennas is that the bandwidth is so narrow, which severely limits their applications. To solve this problem, three broadband techniques, adding impedance matching network, using aperture-coupled feed and using the U-slot antenna, are studied.The feed network of 2×2 four elements array is optimized by ansoft software. Several feeding methods of superconducting antenna are discussed thoroughly. Two feeding methods of arrays with diffent thickness are used to meet the actual manufacture. Gold antenna array and superconducting array (h=0.63mm) are made and tested. The arrays are perfectly matched and the gain of superconducting array is 1.64dB higher than that of the gold array.