Phased array Rotman lens front end devices

A front end of a radar system comprising:

• a substrate through which electromagnetic waves propagate, the substrate including:
• a first end;
• a second end located opposite the first end;
• a cavity space bounded by beam ports along a first side of the cavity space and by array ports along a second side of the cavity space, the cavity space being in operative communication with the beam ports and with the array ports to form a Rotman lens, the cavity space further bounded by radio frequency absorbers along a third side and a fourth side of the cavity space, the second side located opposite the first side, the fourth side located opposite the third side;
• and
• an array of antennas located along the second end of the substrate, each of the antennas being in operative communication with a corresponding one of the array ports,
• wherein the radio frequency absorbers include triangular teeth having vertices, and the triangular teeth are arranged such that lines extending between adjacent vertices are substantially normal to a curvature of a wavefront of the waves in the cavity space during operation of the front end of the radar system,
• wherein the substrate comprises a first set of waveguides that extend between the first end of the substrate and the beam ports and a second set of waveguides that extend between the array ports and the second end of the substrate, each waveguide of the first set of waveguides and the second set of waveguides including a hollow space inside the waveguide and extending in a longitudinal direction from one end of the waveguide to an opposite end of the waveguide, the hollow space having a rectangular cross-section,
• wherein each waveguide in the first set of waveguides of the substrate includes a first polarization rotator,
• wherein each waveguide in the second set of waveguides of the substrate includes a second polarization rotator,
• wherein each of the first polarization rotator and the second polarization rotator includes a corresponding first section, a corresponding iris section, and a corresponding second section in the longitudinal direction,
• wherein, for each of the first polarization rotator and the second polarization rotator, the corresponding first section includes a first set of obstructions that protrude into the hollow space, the corresponding iris section includes second set of obstructions that protrude into the hollow space, and the corresponding second section includes a third set of obstructions that protrude into the hollow space.