New Low-Loss Millimetre-Wave Hybrid Microstrip Antenna Array

A new hybrid configuration which combines a dielectric insular guide feeder with printed microstrip radiators is described. The insular guide is operated in a higher mode to enable efficient transfer of power to the microstrip radiating elements which lie on the substrate region of the guide. The use of an insular guide as opposed to a microstrip line provides a lower feeder loss at millimetre wavelengths while retaining most of the attractive manufacturing aspects of microstrip antennas. A 70 GHz linear array has been constructed by scaling down a version designed at 14 GHz. The measured performance confirms the usefulness of the new hybrid configuration particularly for longer arrays where microstrip feeder loss would be a limiting factor.