A Microwave/Millimeter-Wave Shared-Aperture Antenna Based on Slow-Wave Parallel-Plate Waveguide

Since the coexistence of microwave (MW) and millimeter-wave (MMW) technologies has become the inexorable trend of emerging wireless communication systems, the corresponding antennas are required to support two frequency bands simultaneously. However, the existing MW/MMW shared-aperture antennas are facing challenges in dealing with the interference between two bands and implementing beam steering at both bands. To address these issues, a windowed slow-wave parallel-plate waveguide (WSW-PPW) is proposed as the sharing platform, on which MW and MMW antenna elements can be flexibly arranged. WSW-PPW is implemented by embedding electromagnetic bandgap (EBG) structures into a dual-layer printed PPW. At the MW band, WSW-PPW exhibits a transmission feature for feeding and also integrating MW antenna elements. At the MMW band, WSW-PPW rejects the propagation of electromagnetic waves and functions as artificial magnetic boundaries for dielectric resonator antennas, which are realized by removing subarrays of EBG structures. For demonstration, an MW/MMW shared-aperture antenna is implemented by integrating a
$1\times $
2 MW patch array and a
$1\times $
8 MMW array on this platform. Steerable beams had been independently achieved at both bands. The antenna is fabricated and experimentally verified. The measured results show a reasonable agreement with simulations.