An HTS transceiver for third generation mobile communications

Future third-generation mobile communication systems will require improved sensitivity and selectivity to support the growth in multi-media services, increased coverage, longer talk time and larger numbers of subscribers. The paper describes a transceiver for use in mobile and personal communications base transceiver stations (BTS). Key components of the transceiver are fabricated using thin film high temperature superconductor technologies to achieve, in the receiver chain, enhanced sensitivity and selectivity and, in the transmitter chain, reduced combiner losses and increased selectivity. Cryo-packaging techniques, which provide a long between-service interval are described. The cryogenic r.f. module encapsulation design features novel r.f. and thermal interconnects which obviates the need for long lossy input cables. In-situ tuning methods allow the HTS filters to be optimised at the operating temperature, 60 K, and in vacuum. The transceiver incorporates an integrated miniature Stirling-cycle cooling engine designed for a 5-watt heat lift at 60 K, over an ambient temperature range of -40/spl deg/C to +65/spl deg/C. The control electronics are driven directly from the BTS d.c. supplies. The input power requirement to the cryo-cooler and drive electronics is <250 watts. The design of the cooler is arranged to provide an inherent balance, virtually eliminating vibration. Multiple r.f. transceivers are integrated with a single cryocooler, and together with bypass switching, alarms and lightning protection, are contained within a single mast-head mounted weatherproof housing.