High Resolution Beam-Scanning Leaky-Wave Antenna Array With Phase Difference Reconfigurable Structure Cascaded Butler Matrix

A leaky-wave antenna (LWA) array with high resolution beam scanning capability in two dimensions (2D) is presented in this paper. The antenna array is fed by a substrate integrated waveguide (SIW) Butler matrix cascaded with a phase difference reconfigurable structure (PDRS). By activating different states of the PDRS, the number of phase difference sets at the output ports of the Butler matrix increases from 4 to 36, achieving an 11.25∘ phase resolution. Prototype of the feeding network was first fabricated and measured, the results show that the phase difference range is extended to -180∘ to 180∘, with an imbalance of ±20∘ over 3.9-4.7 GHz. The 2D beam-scanning LWA array prototype was also fabricated and measured. The experiment results demonstrate a beam scanning range from -48∘ to 48∘ in xoz-plane with 29 distinct beams, and a frequency scanning range from -45∘ to 18∘ in yoz-plane across 3.8-4.9 GHz.