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Microwave Particles

• A microwave is an electromagnetic energy with wavelengths ranging between 0.3 – 30 cm (one of the largest wavelengths in the spectrum of electromagnetic energy)

• Their equivalent frequencies in air are between 300 megahertz and 300 gigahertz.

Microwave Particles

• Microwave frequencies are used in many different applications such as:

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• Its most common application is to power microwave emitting chambers in microwave ovens

Principles

• A microwave oven works by passing non-ionizing microwave radiation, usually at a frequency of 2.45 GHz (a)

• Their most common use is to heat up consumables in a microwave reflectant box (the microwave oven)

Principles

• A microwave oven consists of:– High Voltage Transformer– Cavity Magnetron, – Magnetron Control Circuit (usually with a

microcontroller)– Waveguide– Cooking Chamber

Transformer

Transformer

• A device that transfers electrical energy from one circuit to another through coupled, induced wires

or

• The secondary voltage (voltaic output) is determined as the product of the primary voltage (voltaic input) multiplied by the ratio of the number of turns of the wire in the transformer

Np

Ns

Vp

Vs Vp

Np

NsVs

Transformer

• If the number of coils in the output is greater than the number of coils in the input, then the output voltage is “Stepped-Up” (Higher voltaic output)

• If the number of coils in the output is less than the number of coils in the input, then the output voltage is “Stepped-Down” (Lower voltaic output)

Cavity Magnetron

• This device is a high powered vacuum tube that generates the microwaves used to heat the contents inside the microwave oven

Cavity Magnetron

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Magnetron Control Circuit

• Contains:– Control Sensors– Circuit Board– Control Panel with:

» Power Level» Timer

Waveguide

• A device that guides the electromagnetic radiation (the generated microwaves) from the magnetron to the cooking chamber through a predetermined path

Cooking Chamber

• The area of the microwave oven that heats the food in a shielded chamber

• It reflects the microwaves to speed up the process of heating the food

• The shielding concentrates the microwaves and prevents harmful spill-over radiation