Waveguide Single-Plate Matching Transitions
Comprehensive reference data for scaling compact Rectangular-to-Circular (Square-to-Round) transition plates across Microwave and Millimeter-Wave bands. Based on the electromagnetic scaling methodologies verified by Paul Wade (W1GHZ) and Jeffrey Pawlan (WA6KBL).
Transition Geometry & Mechanical Blueprint
The matching plate is positioned precisely at the interface between the rectangular/square guide and the circular guide. The inner aperture features semi-circular sides where the corner radius (r) is exactly half of the aperture height (b).
Scaling Methodology Rules:
The scaling factor (SF) is determined by the ratio of the target rectangular waveguide broad-wall to the WR-90 baseline broad-wall: SF = Target Broad-Wall / 22.860 mm.
All linear dimensions scale proportionally: Target Dimension = Baseline Dimension × SF.
Master Dimension Reference Table (All Bands)
| Waveguide Designation | Frequency Range | Scaling Factor (SF) | Broad-Wall (A) | Ideal Circular ID | Aperture Width (a) | Aperture Height (b) | Corner Radius (r) | Plate Thickness |
|---|---|---|---|---|---|---|---|---|
| WR-90 (X-Band Baseline) | 8.20 – 12.40 GHz | 1.0000 (Baseline) | 22.860 mm | 20.000 mm | 26.386 mm | 16.136 mm | 8.068 mm | 10.687 mm |
| WR-75 (Ku-Band) | 10.00 – 15.00 GHz | 0.8333 | 19.050 mm | 16.667 mm | 21.988 mm | 13.447 mm | 6.723 mm | 8.906 mm |
| WR-42 (K-Band) | 18.00 – 26.50 GHz | 0.4667 | 10.668 mm | 9.333 mm | 12.313 mm | 7.530 mm | 3.765 mm | 4.987 mm |
| WR-22 (Q-Band) | 33.00 – 50.10 GHz | 0.2489 | 5.690 mm | 4.978 mm | 6.568 mm | 4.016 mm | 2.008 mm | 2.660 mm |
| WR-19 (U-Band) | 40.00 – 60.00 GHz | 0.2089 | 4.775 mm | 4.178 mm | 5.512 mm | 3.371 mm | 1.685 mm | 2.232 mm |
| WR-15 (V-Band) | 50.00 – 75.00 GHz | 0.1644 | 3.759 mm | 3.289 mm | 4.339 mm | 2.654 mm | 1.327 mm | 1.757 mm |
| WR-12 (E-Band) | 60.00 – 90.00 GHz | 0.1356 | 3.099 mm | 2.711 mm | 3.577 mm | 2.187 mm | 1.094 mm | 1.449 mm |
Engineering & Machining Guidelines
| Waveguide Band | Practical Implementation & Tooling Notes |
|---|---|
| WR-90 | Verified baseline from W1GHZ paper and WA6KBL design. Yields VSWR < 1.07 when matched precisely. |
| WR-75 | Matches W1GHZ physical experimental data. Yields VSWR < 1.14. |
| WR-42 | Scaled down perfectly for K-band. Great for satellite and amateur radio links around 24 GHz. |
| WR-22 | Dimensions enter the sub-5mm domain. High-precision tooling required for machining. |
| WR-19 | Millimeter-wave transition. Ensure inner corner polishing to avoid high-frequency skin depth scattering. |
| WR-15 | V-Band transition. Max end-mill cutter diameter for the slot corner radius is 2.65 mm. |
| WR-12 | Extremely small dimensions. Recommended to use 2 mm or 1/16 inch tooling for the slot radius. |