A Primary Radiator Using L-shaped Vertical Strip Line with Stub for Planar Antennas at 60 GHz

A primary radiator for 2-dimensional parabolic reflectors was investigated for millimeter-wave planar antennas, which was constructed by a slotted array fed by an oversized waveguide with the 2-dimensional parabolic reflector. The primary radiator consists of the vertical strip transmission line on which an L-shaped array pattern was etched. At first, the length of an L-shaped radiator was decided by calculating the reflection characteristics. Next, spacing between two L-shaped radiators was chosen by calculating the radiation patterns of the L-shaped radiating array. It was obvious that a broad radiation pattern was obtained by selecting a suitable spacing. In addition, a reactive stub was installed on the vertical strip transmission line to suppress the reflection from the L-shaped radiating array. Based on the calculated and measured radiation patterns and related characteristics, it was confirmed that this radiator would be suitable for applications to a primary radiator at millimeter wavelengths.