A breakthrough in photodynamic therapy

An international team led by physics researchers at The University of Texas at Arlington has published a paper in Bioactive Materials that describes a breakthrough method of photodynamic therapy (PDT), an emerging cancer ...


Making microwaves safer for children

A 15-year research and advocacy effort to make microwave ovens safer has led to a change in national manufacturing standards that will make microwaves more difficult for young children to open, protecting them from the severe ...

Diseases, Conditions, Syndromes

Reusing face masks: Are microwaves the answer?

Researchers from Cardiff University have been testing the feasibility of using microwave ovens and dry heat to decontaminate crucial PPE being used to combat the coronavirus pandemic.

Oncology & Cancer

New thermal ablation method for adenoma shows promise

Researchers from the USA (Kansas State University) and the Republic of Ireland (the National University of Ireland Galway) have completed a successful initial test of a new microwave thermal ablation technique, which could ...

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Microwaves, a subset of radio waves, have wavelengths ranging from as long as one meter to as short as one millimeter, or equivalently, with frequencies between 300 MHz (0.3 GHz) and 300 GHz. This broad definition includes both UHF and EHF (millimeter waves), and various sources use different boundaries. In all cases, microwave includes the entire SHF band (3 to 30 GHz, or 10 to 1 cm) at minimum, with RF engineering often putting the lower boundary at 1 GHz (30 cm), and the upper around 100 GHz (3 mm).

Apparatus and techniques may be described qualitatively as "microwave" when the wavelengths of signals are roughly the same as the dimensions of the equipment, so that lumped-element circuit theory is inaccurate. As a consequence, practical microwave technique tends to move away from the discrete resistors, capacitors, and inductors used with lower-frequency radio waves. Instead, distributed circuit elements and transmission-line theory are more useful methods for design and analysis. Open-wire and coaxial transmission lines give way to waveguides and stripline, and lumped-element tuned circuits are replaced by cavity resonators or resonant lines. Effects of reflection, polarization, scattering, diffraction, and atmospheric absorption usually associated with visible light are of practical significance in the study of microwave propagation. The same equations of electromagnetic theory apply at all frequencies.

The prefix "micro-" in "microwave" is not meant to suggest a wavelength in the micrometer range. It indicates that microwaves are "small" compared to waves used in typical radio broadcasting, in that they have shorter wavelengths. The boundaries between far infrared light, terahertz radiation, microwaves, and ultra-high-frequency radio waves are fairly arbitrary and are used variously between different fields of study.

Electromagnetic waves longer (lower frequency) than microwaves are called "radio waves". Electromagnetic radiation with shorter wavelengths may be called "millimeter waves", terahertz radiation or even T-rays. Definitions differ for millimeter wave band, which the IEEE defines as 110 GHz to 300 GHz.

Above 300 GHz, the absorption of electromagnetic radiation by Earth's atmosphere is so great that it is in effect opaque, until the atmosphere becomes transparent again in the so-called infrared and optical window frequency ranges.

This text uses material from Wikipedia, licensed under CC BY-SA