A circular waveguide refers to a waveguide with a circular cross-section.
The lowest order propagation mode in a circular waveguide is TE11, which provides minimal signal degradation.
The possible TM modes in circular waveguides are TM01, TM02, TM11, and TM12.
The modes maintained by circular waveguides have many similarities with those of rectangular waveguides. For example, they can be classified as transverse electric modes (TE modes) without electric field components along the guiding axis, or as transverse magnetic modes (TM modes) without magnetic field components along the guiding axis.
| Frequency Band | Frequency Range | Circular WaveguideDiameter, Inches (mm) | Cover Flange (Brass)MIL-F- 3922 UG | Flange Type | |
| X | LOW | 8.2-9.97 | 1.094 (27.79) | 53-001 UG-39/U | Square |
| MID | 8.5-11.6 | 0.938 (23.83) | |||
| HIGH | 9.97-12.4 | 0.797 (20.24) | |||
| Ku | LOW | 12.4-15.9 | 0.688 (17.48) | 53-005 UG-1666/U | Square |
| MID | 13.4-18.0 | 0.594 (15.08) | |||
| HIGH | 15.9-18.0 | 0.500 (12.70) | |||
| K | LOW | 17.5-20.5 | 0.455 (11.56) | 54-001 UG-595/U | Square |
| MID | 20-24.5 | 0.396 (10.06) | |||
| HIGH | 24-26.5 | 0.328 (8.33) | |||
| Ka | LOW | 26.5-33 | 0.315 (8.00) | 54-003 UG-595/U | Square |
| MID | 33-38.5 | 0.250 (6.35) | |||
| HIGH | 38.5-40 | 0.219 (5.56) | |||
| Q | LOW | 33-38.5 | 0.250 (6.35) | 67B-006 UG-383/U | Round |
| MID | 38.5-43 | 0.219 (5.56) | |||
| HIGH | 43-50 | 0.188 (4.78) | |||
| U | LOW | 40-43 | 0.210 (5.33) | 67B-007 UG-383/U-M | Round |
| MID | 43-50 | 0.188 (4.78) | |||
| HIGH | 50-60 | 0.165 (4.19) | |||
| V | LOW | 50-58 | 0.165 (4.19) | 67B-008 UG-385/U | Round |
| MID | 58-68 | 0.141 (3.58) | |||
| HIGH | 68-75 | 0.125 (3.18) | |||
| E | LOW | 60-66 | 0.136 (3.45) | 67B-009 UG-387/U | Round |
| MID | 66-82 | 0.125 (3.18) | |||
| HIGH | 82-90 | 0.094 (2.39) | |||
| W | LOW | 75-88 | 0.112 (2.84) | 67B-010 UG-387/U-M | Round |
| HIGH | 88-110 | 0.094 (2.39) | |||
| F | LOW | 90-115 | 0.089 (2.26) | -UG-387/U-M | Round |
| HIGH | 115-140 | 0.075 (1.91) | |||
| D | LOW | 110-140 | 0.073 (1.85) | -UG-387/U-M | Round |
| HIGH | 140-160 | 0.059 (1.50) | |||
| G | LOW | 140-180 | 0.058 (1.47) | -UG-387/U-M | Round |
| HIGH | 180-220 | 0.045 (1.14) | |||
| — | — | 170-260 | 0.049 (1.25) | -UG-387/U-M | Round |
| — | — | 220-325 | 0.039 (0.99) | -UG-387/U-M | Round
|
Note: The circular waveguide diameters provided correspond to each frequency band.
