Submillimeter Wavelength 2-D Frequency Scanning Antenna Based on Slotted Waveguides Fed Through a Phase Shifting Network

This paper describes a 2-D frequency scanning array, operating in the 240–310-GHz frequency range, which is intended to be used in electromagnetic imaging applications. The proposed antenna combines eight slotted waveguides that are parallel fed through a frequency-dependent phase shifting network. As the working frequency is swept in the considered range, the inherent frequency-dependent behavior of the slotted waveguide causes beam scanning in one plane, while the progressive phase shift introduced by the feeding network provides beam steering in the perpendicular direction. The influence of the particular negative effects that suffer the employed structures on the array performance is carefully analyzed to determine the viability of this approach. A prototype has been implemented and experimentally characterized. The manufactured antenna presents a measured 20-dBi minimum gain and it is able to scan a $60 {^{\circ }}\times 20 {^{\circ }}$ space region, which would be large enough for a great number of imaging applications.