New Algorithm to Convert 3-Focal Rotman Lens into Non-Focal One to Decrease Phase Errors, as A Feed For Phased Array Antennas

Rotman Lens antennas are widely used as a feed for phased array antennas because of their unique features. This lens is usually designed with 3 focal points. One of the major problems of this method is the phase error specially for big aperture lenses. Much efforts has been done to reduce this error. Recently Non-Focal Rotman Lens has been proposed to reduces phase error effectively but the major problem of this method is undesired places of the input and output ports. These ports are only optimized to reduce the phase error but are not suitable for implementation because they produce matching and coupling problems. In this essay a new approach of Rotman Lens is proposed that convert 3-Focal Rotman Lenses into Non-Focal ones and decreases phase error greatly with implementation capability. A lens with 7 input ports and 16 output ports is designed with this proposed new method. Phase error and implementation capability are evaluated with full wave simulation. Results show that maximum and average phase errors of the input and output ports decrease greatly and there is no problem to implement this lens.