Planar waveguide feed for V-band Bull's eye antenna

Abstract

A technique is presented for feeding leaky-wave Bull's eye antennas from a planar waveguide, based on a planar to rectangular waveguide transition and a milled waveguide extension. Bull's eye antennas are low-profile planar antennas that exploit leaky wave principles to achieve high gain. Currently Bull's eye antennas use hollow waveguide feeds (rectangular or circular), but lower-cost feed options open up new applications for the antenna, particularly if it can permit compact overall size due to tight integration with the underlying millimeter-wave circuit (e.g. in small satellites or communications backhaul on earth). While substrate-integrate-waveguides often offer better performance than microstrip waveguides at millimeter wave frequencies, the feed integration challenge is substantially similar and we were able to access a suitable fabrication technology for microstrip waveguides. We produced a prototype microstrip-fed Bull's eye antenna operating at 60 GHz and measured its far field radiation pattern to confirm that the antenna's radiation pattern was not substantially affected by the change in the feed.