220-320 GHz Hemispherical Lens Antennas Using Digital Light Processed Photopolymers

This paper presents a 220-320-GHz hemispherical lens antenna fabricated using photopolymer-based additive manufacture and directly fed by the standard WR-3 rectangular waveguide without any additional waveguide extension. The microfabrication process is based on digital light processing rapid prototyping using the Monocure 3DR3582C resin-based photocurable polymer. This gives various key advantages, including ease of antenna fabrication, manufacturing speed, and cost-effectiveness due to its rapid fabrication capability. Even though the photopolymer is found to have a loss tangent of 0.034 at 320 GHz, the all-polymer lens antennas still achieve a fractional bandwidth of 37%, covering the whole 220-320-GHz WR-3 waveguide band with a measured gain of approximately 16 dBi at 0° over the whole band. A measured return loss of better than 14 dB is achieved from 220 to 320 GHz with a half-power beamwidth of approximately 12°, which is relatively constant over the whole WR-3 band.