Microwave heating cavities and applicators - Microwave-Assisted Concrete Technology: Production, Demolition and Recycling - page 229

The k r parameter in Equation 6.17 can be obtained using the following
expression:

kk
r

= 0 ε (6.18)

r

The solution to Equation 6.12 can be obtained using various electro-
magnetic simulation packages such as COMSOL or mathematical simu-
lation software such as Mathematica and MATLAB • . The distribution
of the electric field in a rectangular open-ended waveguide is shown in
Figure 6.29.
One type of open-ended waveguide applicator is the flared horn open-
ended applicator, in which the side of the applicator closest to the load is
flared to provide an incident area that is larger than the waveguide cross
section. Horn open-ended applicators are commonly used in a variety of
applications, including sensing and heating applications. A rectangular
waveguide horn is shown in Figure 6.24. One advantage of open-ended
horns over open-ended waveguide applicators is the higher penetration of
the fringing field into the load. In open-ended horns, the penetration depth
of the field is usually limited only by the load's penetration depth, which is
determined by the material's attenuation factor as described in Chapter 1.
The higher penetration depth of horn applicators is mainly because the

1

Z = 0 cm
Z = 1 cm
Z = 2 cm
Z = 3 cm

0.8

y

0.6

z

x

0.4

Rectangular open-ended
waveguide cross section

0.2

0

0 0.5 1 1.5 2 2.5

y (cm)

Figure 6.29 Electric field distribution in a rectangular waveguide applicator in TE 10 mode.
(Reprinted, with permission, from Habash, R.W.Y., Non-invasive Microwave
Hyperthermia, PhD dissertation, Indian Institute of Science, Bangalore.)