Compact Rotman Lens Design using Klopfenstein Taper Lines

The fifth-generation (5G) communication system not only demands compact designs but also calls for innovative beam-steering approaches. The Rotman lens is one of the beam steering devices that can be used for such applications. However, it demands a considerable amount of real estate to accommodate transmission lines attached to its beam, dummy, and array ports. These tapered transmission lines act as impedance transformers and the entire performance of the lens degrades significantly unless these lines are properly designed. In this work, we show how to use Klopfenstein taper lines to design the Rotman lens. The lens designed in this manner not only has small footprints but the design methodology also paves the way for software design to automate the design of such lenses.