Low-Profile Rectangular to Circular Waveguide Transition

The patent replaces the traditional mechanical milling process of bulk metal with a PCB fabrication process using laminated substrates, ground planes, and microstrip lines. This substitution transforms the heavy mechanical construction into a lightweight electrical circuit board structure that achieves the same waveguide transition function with dramatically reduced weight and size.

The invention transitions from a three-dimensional bulk metal structure to a planar two-dimensional PCB layout. By using top and bottom ground planes separated by a substrate thickness, the waveguide transition is achieved in the vertical dimension through lamination, allowing the structure to be extremely thin in the propagation direction while maintaining effective electromagnetic wave guidance.

The patent replaces expensive precision mechanical milling of bulk metal with standard PCB fabrication processes including substrate lamination, ground plane deposition, and microstrip patterning. These are well-established, cost-effective manufacturing techniques that eliminate the need for expensive custom metal machining while achieving the same electromagnetic waveguiding function.

The invention changes the fundamental construction parameters from bulk metal dimensions to PCB substrate thickness and copper trace geometry. By controlling the substrate thickness, ground plane dimensions, and microstrip line characteristics, the waveguide transition is achieved through electrical parameter optimization rather than mechanical dimensioning, enabling standardized manufacturing at lower cost.

The patent compresses the waveguide transition from a long linear path into a thin vertical structure by using top and bottom ground planes separated by substrate thickness. The electromagnetic field transitions between rectangular and circular modes through the vertical lamination structure rather than along a long horizontal path, reducing the length in the propagation direction to just the substrate thickness.

The PCB substrate structure simultaneously serves multiple functions: it provides the dielectric medium for wave propagation, defines the ground planes for field confinement, creates the microstrip transmission lines for mode conversion, and acts as the mechanical support structure. This multi-functionality eliminates the need for separate components that would increase the overall length.