ALPSS: A millimetre-wave aperture-coupled patch antenna on a substrate lens

The feasibility of millimetre-wave (mm-wave) aperture-coupled patch antennas, printed at the back surface of substrate-lenses is demonstrated and the corresponding radiation characteristics are investigated. A specific realisation of such an air-lens-patch-slot-strip (ALPSS) antenna on a low-permittivity epsilon(r) = 4.0 extended hemispherical lens substrate is theoretically and experimentally characterised at 70GHz. It is demonstrated that the ALPSS antenna exhibits clean, axially symmetric patterns of low cross-polarisation (-26dB), a directivity of 30.4dB and the 3dB pattern full-beamwidth remains within 6 degrees-5 degrees between 60-80GHz. In addition, a very-high front-to-back (F/B) ratio, of the order of 50dB is measured at 70GHz, despite the absence of a backing ground-plane. The ALPSS antenna is well suited for low-cost broadband point-to-point communications and collision avoidance applications.