Mode conversion losses from HE11 in a miter bend with a flat mirror can be estimated from the diameter (D) and the wavelength (lambda) using the formula:
mode conversion loss per miter bend ~ 2.4 (lambda/D)3/2 dB
This formula represents an average over a range of frequencies. The actual loss can be expected to be somewhat above or below this estimate. Some comparisons of measured and calculated losses on waveguide runs with 2 - 8 miter bends:
waveguide
diameter
|
frequency
|
miter bends
tested
|
experimental loss
per miter bend
|
calculated loss
per miter bend
|
|
31.75 mm
|
110 GHz
|
6
|
0.06 dB
|
0.06 dB
|
|
63.5 mm
|
60 GHz
|
8
|
0.03 dB
|
0.05 dB
|
|
31.75 mm
|
56 - 64 GHz
|
2
|
0.15 dB
|
0.15 dB
|