Design of Multi-Beam Antenna Based on Rotman Lens

A multi-beam antenna fed by Rotman lens is presented in this paper. A Rotman lens and a ten-element printed Yagi antenna array make up the antenna system. 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 fabricated and measured, covering a wide scanning angle of +/- 30 degrees. The measured beam patterns show that the seven beam gains are distributed from 11.9 to 13.6 dBi under operating of 8.15 GHz. Both the simulated and measured results are used to verify the design approach.