Beam forming network using 4×4 narrowband butler matrix for tracking and localization applications

This paper proposes the design of beam forming network using single layer 4×4 Narrow butler matrix along with microstrip antenna array which is used for tracking and localization applications. The purpose of this design is to orient the orthogonal beams in various directions which is achieved using butler matrix. The conventional design of butler matrix consists of 3dB hybrid coupler, 0dB cross over coupler and 45° phase shifter. In order to develop this as a complete beam forming network each output port of the butler matrix is fed as input to microstrip antenna. The proposed design operates at a frequency of ISM band 2.4 GHz and each individual component is simulated using Advanced Design System (ADS). The area of the design is 190 × 240 mm² and is made of FR4 substrate with 4.6 as dielectric constant. The designed butler matrix meets with amplitude imbalance of less than 0.73dB and phase mismatch of ±5.6°. The return loss for this complete beam forming structure is −33.3dB.