Design of a novel switched four beam array antenna for millimeter wave

Phased array system is used to scan an antenna beam to given angles in space. It consists of multiple stationary antenna elements, which are fed coherently, and uses variable phase shifter at each element. The phase shifter is one of the main parts of phased array antennas but it causes loss and complexity is making it. Inevitably, recent demands for highly flexible array control have highlighted the feed network offered by digital control such as, butler matrix for less complexity and loss. The butler matrix makes the orthogonal sets of beams with uniform aperture illumination using switches. But it needs four 90deg hybrids and two crossovers to make a four beam array antenna. These 90deg hybrids and crossovers worsen not only the antenna phase characteristics and operating bandwidth but also the system complexity. We propose a simple feed network for a four beam array antenna with just one 90deg hybrid, two switches, and delay lines. The merit of the proposed antenna is less complexity, in comparison with four beam butler matrix and easy fabrication due to planar structure.