Four-beam antenna array for 24 GHz applications fed by 4 × 4 Butler matrix

A four-beam antenna array operating within 24 GHz frequency range has been developed. As a feeding network of such antenna a 4 × 4 Butler matrix has been designed utilizing a low-cost microwave laminate having permittivity 3.38 and thickness 0.203 mm. The developed Butler matrix consists of an appropriate connection of six directional couplers, two of which have been used to form a transmission-line crossover. The designed matrix has been integrated with the four-element linear antenna array confirming the usability of the utilized Butler matrix in beam-scanning applications.