Fully-Metallic Additively Manufactured Monolithic Double-Ridged Waveguide Rotman Lens in the K/K_a-Band

Area of Science:

• Additive Manufacturing
• Microwave Engineering
• Antenna Systems

Background:

• Rotman lenses are key quasi-optical beamformers for phased array antennas.
• Traditional manufacturing methods for Rotman lenses can be complex and costly.
• Additive manufacturing offers potential for integrated, single-part component fabrication.

Purpose of the Study:

• To design and experimentally validate a fully-metallic, additively manufactured 10x10 Rotman lens.
• To achieve wideband operation covering K/Ka-band satellite communication frequencies (17.3 GHz to 30 GHz).
• To optimize the design for vertical 3D printing, minimizing support structures.

Main Methods:

• Design of a double-ridged waveguide Rotman lens.
• Additive manufacturing of the monolithic lens.
• Experimental validation including S-parameter measurements and phase error analysis.
• Synthesis of array factors to assess beamforming stability.

Main Results:

• Successful fabrication of a single-part, fully-metallic Rotman lens.
• Measured insertion losses of 0.5 dB (lower band) and 0.8 dB (upper band).
• Reflection and coupling coefficients below -11.5 dB across the operating band.
• Standard deviation of residual phase error below 10° in measurements.
• Stable beamforming functionality demonstrated over the K/Ka-band.

Conclusions:

• Additive manufacturing enables the creation of complex, monolithic Rotman lenses.
• The fabricated lens meets performance requirements for K/Ka-band satellite communications.
• This monolithic design is a significant advancement for integrated antenna systems.
• The approach is suitable for compact dual-stack configurations in planar arrays.