High-temperature superconducting beam forming network for communication system applications

This paper presents an application of the high-temperature superconductor (HTS) technology to the development of a high-performance antenna beam forming network (BFN) for communication systems, Design and measurements are made in Ku-band with a multiple power divider technique involving a cascade of 3-dB branch-line couplers, Three microstrip couplers are integrated to form a one-to-four BFN, An experimental prototype is fabricated with TlBaCaCuO thin film deposited onto LaAlO3 substrate, Power handling capability of related HTS components such as line, bend, and BFN are also studied together with third-order intermodulation characteristics. It is shown that theoretical prediction is consistent with experimental results, presenting insertion loss of the four output ports ranging from 6.1-6.4 dB and return loss better than 14 dB at 11.95 GHz, These preliminary results demonstrate the potential of extending such a power divider technique in designing an N-port BFN, It is also indicated that the proposed HTS BFN scheme can offer advantages compared to its conventional counterpart, namely, a significant reduction in size/weight and low power loss.