Compact 2-D Beam-Scanning Multibeam Antenna Based on Modified Partial Maxwell Fish-Eye

A compact 2-D beam-scanning multibeam antenna based on a modified partial Maxwell fish-eye (PMFE) is proposed in this letter. The antenna comprises a modified PMFE beamforming network and leaky-wave antennas (LWAs) array. The conventional HMFE is redesigned using ray‑tracing method by increasing the refractive index at the lens rim to values greater than one, which facilitates simple fabrication with printed circuit board technology. The PMFE is discretized into a series of concentric rings: inner rings are filled with air-hole unit cells, while outer rings consist of split-ring resonator unit cells. This design not only maintains a wide bandwidth but also achieves a refractive index as low as possible. To enhance the scanning rate, a substrate integrated waveguide-based spoof surface plasmon polaritons transmission line is used to excite two longitudinally identical slots. A prototype is fabricated and measured. The results show that the proposed antenna achieves a frequency-controlled beam scanning range from -56° to 58° with a scanning rate of 5.8, and a multibeam scanning range from -39° to 37°.