An original implementation of a TX/RX transceiver for future UMTS base stations is proposed in this paper. Machined Foam substrates are stacked at first for implementing a square patch antenna on a composite thick support, then delivering interesting performances in terms of bandwidth and efficiency with respect to planar solutions. Active and passive devices are inserted within a shielded cavity created under the patch, then preventing from size constraints at such frequencies as well as insertion loss and parasitic radiations. A complete experimental procedure is presented for both TX and RX operating modes.