Implementation of a low-loss wide-band flat-topped beam-forming network based on butler martix

A low-loss wide-band flat-topped beam-forming network is designed and implemented. The flat-topped pattern can be formed expediently by superposing the beams of Butler matrix. In order to achieve the direct beam superposition, the additional phase shifts are derived based on Woodward-Lawson (W-L) method to ensure the central phases of beams are same. To reduce the loss of beam-forming network, the suspend stripline structure is adopted. Moreover, the wideband coupler, crossover and phase shifter are exploited and the network possesses the feature of wideband. Finally, the fabricated network based on 8×8 Butler matrix is connected with 8-element array and a 1:8 power divider. The measured patterns are fat-topped and similar in a wide band.