An implemented non-focal Rotman lens

Abstract

Rotman lens is a feed network which has many applications in the field of phased array antennas. Dealing with the phase error is very important in Rotman lens design process. Designing Rotman lens using a non-focal idea has been done recently where the phase error is just reduced by optimizing the port positions. The method cannot be constructed easily because the location of the ports are unsuitable which causes mismatching and coupling. In this paper, a new process is presented to implement the lens, which converts three-focal Rotman Lens to non-focal and the phase error is properly reduced by using a simple procedure. The proposed non-focal Rotman lens has been implemented at 10GHz. Simulation and measurement results proved that the method is implementable. Furthermore, in comparison with previous reported work, the average improvement of the maximum phase error in the proposed lens, with 5 beam port and 5 array ports with overall lens size of 15*15 cm2, is 36% better.