Microwaves
Image Source (Wikipedia)
What Are Microwaves?
Microwaves are a form of Electromagnetic Radiation with Wavelengths which measure from 1 metre to 1 millimetre. They have long wavelengths, oscillate (vibrate) at low frequencies and are relatively low energy waves compared to the rest of the EM spectrum. They are similar in characteristics to Radio waves, so much so, that they share a classification system which categorises them in terms of their respective frequencies. For example: microwaves are either of Ultra High Frequency (UHF) between 300 Megahertz and 3 Gigahertz; or Extremely High Frequency (EHF) between 30 Megahertz and 300 Megahertz.
The generated image formed of a breast tumour using microwave tomography. Image Source (Microwave Engineering Services)
Safety
Microwaves are described as “non-ionising radiation”, a term which means that the energy which they possess will not cause the composition of human cells to change in an unexpected or dangerous way. Ionised cells can cause chemical reactions within the body which may be harmful. These microwave carry such little energy compared to Gamma Rays and X-Rays.
Uses
Microwaves are used every day in communication systems, like your mobile phone, and perhaps more commonly, as a means of heating your food in the kitchen. However, their low energies makes them ideal for safe use in medicine both as a tool for treatment and for diagnostic purposes. Microwave Ablation is a procedure at the forefront of cancer treatment research which can be explored here. Microwave Tomography is an imaging method used to detect cancerous tumours in the breast, this will also be discussed here.
Production
In the medical world, microwaves are efficient to produce due to their practical wavelength sizes between 1 metre and 1 millimetre. The most common way to produce these waves is by a cavity magnetron. This is a small device which fires a beam of electrons though a vacuum tube where they are guided by a magnetic field to move past hollow cavities of specific length. When the electrons pass these cavities they will produce microwaves which vibrate inside the tubes. These microwaves can then be guided to be of use elsewhere via carrier tubes called waveguides. For more information on the production of microwaves, click here.
