Slotted Waveguide Frequency-Scanned Slow-Wave Antenna with Reduced Sensitivity of the Closed Stopband at Millimeter-Wave Frequencies

Abstract

In this paper, we describe the design and implementation of a frequency-scanned slotted waveguide antenna with a closed stopband which has a low sensitivity to the fabrication errors. The antenna is implemented as a slotted slow-wave waveguide by loading a standard WR22 waveguide with elliptical posts. A systematic design approach for scanning through broadside and closing the stopband with a reduced sensitivity to fabrication tolerances is discussed in the paper. This approach allows for fabricating the antenna using CNC machining with a tolerance of +/-0.13 mm for the waveguide and a tolerance of +/-0.05 mm for the posts. The antenna beam can be steered from -38° to +27° by changing the frequency from 27 GHz to 34.7 GHz. The effective radiating length of the antenna is $27.6\lambda $ corresponding to a 1.75° half-power beamwidth while its radiation efficiency changes between 54% and 90% throughout the steering range.