Superconducting sub-array module as T/R module for X-band active phased array antenna

We have developed a high-sensitivity superconducting sub-array module for an X-band active phased array antenna. This sub-array module can be assumed as a multichannel T/R module with 16 antenna elements. And the module also includes 16 transmitting (TX) channels and 16 receiving (RX) channels with high-Tc superconducting (HTS) filters. By means of this sub-array module, a high-sensitivity antenna can be easily available for wireless applications such as communication systems and radar systems. In this paper, we describe the newly developed X-band superconducting sub-array module that is applicable as a key component for an active phased array antenna. In particular, each Rx channel contains a cryogenic circuit that mainly consists of HTS filters and a low-noise amplifier (LNA) cooled at 77 K for low insertion loss and low internal noise. 16 cryogenic circuits are contained within a 100 mm×100 mm×36.5 mm vacuum chamber and cooled by a small cooler. By using HTS filters and cooling, noise temperature of the RX channels was reduced to less than 60 K and naturally the high-sensitivity X-band sub-array module was realized. Additionally, the features of the sub-array module, such as low amplitude deviation and good phase linearity, indicated that both TX channels and RX channels were appropriate for an active phased array antenna.