since I've read that wave guide bends should have
a radius of greater than two wavelengths, I was
wondering why the bend radius limits of wr75 and
most other sizes of flexible waveguide are less
than two wavelengths, and I can't find any specifications
addressing this.
Shouldn't the flex
waveguide bend adhere to the two wavelength radius
standard?Here I will "paste" some
of the literature I've read. This literature can
be found at
http://www.tpub.com/content/et/14092/css/14092_78.htm
and many other places. It is from the NAVY Training
guide (the "figures" did not copy and paste):
Waveguide Bends The size, shape, and dielectric
material of a waveguide must be constant throughout
its length for energy to move from one end to the
other without reflections. Any abrupt change in
its size or shape can cause reflections and a loss
in overall efficiency. When such a change is necessary,
the bends, twists, and joints of the waveguides
must meet certain conditions to prevent reflections.
Waveguides maybe bent in several ways that do not
cause reflections.
One way is the gradual
bend shown in figure 3-48. This gradual bend is
known as an E bend because it distorts the E fields.
The E bend must have a radius greater than two wavelengths
to prevent reflections. Figure 3-48.—Gradual E bend.
Another common bend is the gradual H bend
(fig. 3-49). It is called an H bend because the
H fields are distorted when a waveguide is bent
in this manner. Again, the radius of the bend must
be greater than two wavelengths to prevent reflections.
Neither the E bend in the “a” dimension nor the
H bend in the “b” dimension changes the normal mode
of operation. Figure 3-49.—Gradual H bend. 3-22
