Ku-Band Rotman Lens with 4 Output Ports

The Ku-band Rotman lens, which is used to feed the antenna system for the purpose of forming a multibeam radiation pattern, is presented. S-11 parameter of the Rotman lens reaches < -10 dB in the operating frequency range. For the obtained lens geometry, the scanning angle of the antenna with four linear arrays at a frequency of 11.7 GHz is -20... +20 degrees according to modelling, and -25... +25 degrees according to measurements. The dip between adjacent lobes of the radiation pattern does not exceed 10 dBi while gain is 19 dB. The distance between the array elements is 10 mm. The input impedance of the ports is 50 ohms. Theoretical analysis and electrodynamic modeling of antenna components is performed using the full-wave finite-difference method in the time domain. The antenna array prototype is made on an FR-4 dielectric substrate with dimensions of 51x46 mm and a dielectric thickness of 500 mu m and copper metallization of 35 mu m. This provides the possibility of passive scanning in the range of +/- 20 degrees. The radiation pattern and VSWR of the antenna array are obtained when the first port was excited using a spectrum analyzer and a vector network analyzer. A comparative analysis of the results of electrodynamic modeling and experiment are carried out. The results of modeling the radiation characteristics and matching are presented, which are qualitatively consistent with the experimental data. The developed antenna system can be used in narrowband data transmission systems of the Ku frequency range.