Design of Multi-Beam Antenna Based on Rotman Lens

A multi-beam antenna fed by Rotman lens is presented in this paper. The antenna system is composed of a Rotman lens and a 8x8 printed dipole antenna array. By properly comparing optical aberrations, expressing as the normalized path length errors, the suitable ratio of on-axis to off-axis focal length (g = G/F) is acquired so as to minimize phase errors for the array elements. Ten dummy ports are used to reduce the deterioration of performance due to energy reflection. A sample antenna was simulated, covering a wide scanning angle of +/- 40 degrees. The simulated beam patterns show that the eleven beam gains are distributed from 17.8 to 19.9 dBi under operating of 3.15 GHz, and similar results are obtained over 20% of the relative bandwidth. The great simulated results are used to verify the design approach.