WR Designation
Understanding WR Waveguide Designations
The WR naming system provides a standardized way to specify waveguide sizes across the entire microwave and millimeter-wave spectrum. Each WR size has a defined broad wall dimension (a), narrow wall dimension (b = a/2), cutoff frequency, and recommended operating band. Understanding WR designations is essential for specifying and ordering waveguide components.
Standard WR Sizes
| WR Size | a (inches) | Band | Freq Range (GHz) |
|---|---|---|---|
| WR-650 | 6.500 | L | 1.12-1.70 |
| WR-284 | 2.840 | S | 2.60-3.95 |
| WR-137 | 1.372 | C | 5.85-8.20 |
| WR-90 | 0.900 | X | 8.20-12.40 |
| WR-62 | 0.622 | Ku | 12.40-18.00 |
| WR-42 | 0.420 | K | 18.00-26.50 |
| WR-28 | 0.280 | Ka | 26.50-40.00 |
| WR-15 | 0.148 | V | 50.00-75.00 |
| WR-10 | 0.100 | W | 75.00-110.00 |
| WR-6 | 0.065 | D | 110.00-170.00 |
| WR-3 | 0.034 | G | 220.00-325.00 |
WR-90: a = 0.900 in = 22.86 mm
b = a/2 = 0.450 in = 11.43 mm
TE10 cutoff: fc = c/(2a)
WR-90: fc = 6.557 GHz
Operating band: 1.25 fc to 1.9 fc
= 8.20 to 12.45 GHz
Frequently Asked Questions
What does WR mean in waveguide?
WR stands for Waveguide Rectangular. The number following WR represents the broad wall internal dimension in hundredths of an inch. WR-90 has a broad wall of 0.900 inches. This dimension determines the cutoff frequency and operating band.
How do I choose the right WR size?
Select the WR size whose recommended operating frequency range covers your application frequency. The operating range is typically 1.25 to 1.9 times the TE10 cutoff frequency. For 10 GHz, use WR-90. For 30 GHz, use WR-28. For 94 GHz, use WR-10.
Can I use waveguide outside its recommended band?
Below cutoff, signals cannot propagate (evanescent mode). Above the upper limit, higher-order modes can propagate, causing signal distortion and unpredictable behavior. Stay within the recommended band for reliable single-mode operation.