Microwave heating cavities and applicators - Microwave-Assisted Concrete Technology: Production, Demolition and Recycling - page 233

vicinity of the heating system, and reduce wastage of energy. Among these
objectives, achieving the second is perhaps the most difficult as interference
with communication devices may occur in situations involving relatively
low-power leakages. However, as described in Chapter 1, most commercial
microwave heating systems are designed to use ISM frequencies at which
the interference of the microwave heating system itself with adjacent com-
munication and instrumentation systems is expected to be minimal.
Microwave heating systems invariably make use of metallic enclosures
and gaskets to reduce leakage from doors and seams. If designed and manu-
factured properly, these should be sufficient to ensure the safety and health
of operators (Figure 6.31). These safety measures are especially effective
in multimode cavity applicators, which are usually fully enclosed with all
the interfaces of the enclosure itself seamlessly welded to prevent leakages
(Figure 6.32).
However, minimising microwave power leakage is usually challenging in
continuous-throughput microwave heating systems as the microwave cav-
ity has inlet and outlet ports. If not designed properly, microwave power
can easily leak through these inlet and outlet ports. In addition, many
microwave heating systems may require the presence of other openings for
instrumentation purposes, such as openings for thermal cameras, which
require a direct line of sight to the load and for optical fibre temperature
sensors to pass through. Such openings contribute directly to leakage of the
microwave power.
To minimise leakage of microwave power from the inlet and outlet
ports of continuous-throughput microwave heating systems, these should
Figure 6. 31 RF gasket of the chamber's door.