Design of a broadband and wide scan angle Rotman lens

The authors consider the design of a broadband lens (2.125:1 bandwidth) that has nonorthogonal beams (overlapping at the -3-dB point at the high end of the frequency band) covering a wide angular sector (+or-45 degrees ). The design challenges are to minimize the amplitude ripple level across the output (antenna) ports when any one of the input (beam) ports is excited and to provide well-matched ports accessing the lens´ cavity. By reducing the amplitude ripple, the output port phase deviation from a linear phase slope is inherently kept low. An analytical design method is proposed that will allow these goals to be met.<>