Novel monolithic ultra-wideband unilateral 4-port junction using distributed amplification techniques

A novel active unilateral 4-port junction operating over 1 to 20 GHz has been demonstrated in monolithic microwave integrated circuit (MMIC) technology, using distributed amplifier techniques, and was capable of covering an extremely wide frequency range. The circuit had unique unilateral characteristics with a relatively constant insertion loss and high isolation, and could replace isolators, circulators, and directional couplers in many ultra-wideband applications. The prototype had insertion losses of approximately 5 dB and excellent port-to-port isolation.<>