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Three security scanners using millimeter waves were put into use at Schiphol Airport in Amsterdam on 15 May 2007, with more expected to be installed later. The passenger's head is masked from the view of the security personnel.

According to Farran Technologies, a manufacturer of one model of the millimeter wave scanner, the technology exists to extend the search area to as far as 50 meters beyond the scanning area which would allow security workers to scan a large number of people without their awareness that they are being scanned.

Medicine

Most widely used in former USSR nations,low intensity (usually 10 mW/cm2 or less) electromagnetic radiation of extremely high frequency (especially in the range 40 - 70 GHz, which corresponds to wavelength of 7.5 - 4.3 mm) is used in human medicine for the treatment of many types of diseases. This type of therapy is called Millimeter Wave (MMW) Therapy or Extremely High Frequency (EHF) Therapy. More than 10 000 devices are used for Millimeter Wave Therapy worldwide  and more than a million people have been successfully treated with millimeter wave therapy during its documented history. Established in 1992, the Russian Journal Millimeter waves in biology and medicine is dedicated to the scientific basis and clinical applications of Millimeter Wave Therapy. More than 50 issues of it have been published.

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Telecommunications

In the United States, the band 38.6 - 40.0 GHz is used for licensed high-speed microwave data links, and the 60 GHz band can be used for unlicensed short range (1.7 km) data links with data throughputs up to 2.5 Gbit/s. It is used commonly in flat terrain.The 71-76, 81-86 and 92–95 GHz bands are also used for point-to-point high-bandwidth communication links. These frequencies, as opposed to the 60 GHz frequency, require a transmitting license in the US from the Federal Communications Commission (FCC), though they do not suffer from the effects of oxygen absorption as the 60 GHz does. There are plans for 10 Gbit/s links using these frequencies as well. In the case of the 92–95 GHz band, a small 100 MHz range has been reserved for space-borne radios, making this reserved range limited to a transmission rate of under a few gigabits per second.

The band is essentially undeveloped and available for use in a broad range of new products and services, including high-speed, point-to-point wireless local area networks and broadband Internet access. WirelessHD is another recent technology that operates near the 60 GHz range. Highly directional, "pencil-beam" signal characteristics permit systems in these bands to be engineered in close proximity to one another without causing interference. Potential applications include radar systems with very high resolution.

Uses of the millimeter wave bands include point-to-point communications, intersatellite links, and point-to-multipoint communications.

Because of shorter wavelengths, the band permits the use of smaller antennas than would be required for similar circumstances in the lower bands, to achieve the same high directivity and high gain. The immediate consequence of this high directivity, coupled with the high free space loss at these frequencies, is the possibility of a more efficient use of the spectrum for point-to-multipoint applications. Since a greater number of highly directive antennas can be placed in a given area than less directive antennas, the net result is higher reuse of the spectrum, and higher density of users, as compared to lower frequencies. Furthermore, because one can place more voice channels or broadband information using a higher frequency to transmit the information, this spectrum could potentially be used as a replacement for or supplement to fiber optics.

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Extremely high frequency is the highest radio frequency band. EHF runs the range of frequencies from 30 to 300 gigahertz, above which electromagnetic radiation is considered to be low (or far) infrared light, also referred to as terahertz radiation. This band has a wavelength of ten to one millimetre, giving it the name millimeter band or millimetre wave, sometimes abbreviated MMW or mmW.

Compared to lower bands, terrestrial radio signals in this band are extremely prone to atmospheric attenuation, making them of very little use over long distances. In particular, signals in the 57–64 GHz region are subject to a resonance of the oxygen molecule and are severely attenuated. Even over relatively short distances, rain fade is a serious problem, caused when absorption by rain reduces signal strength. In climates other than deserts absorption due to humidity also has an impact on propagation. While this absorption limits potential communications range, it also allows for smaller frequency reuse distances than lower frequencies. The small wavelength allows modest size antennas to have a small beam width, further increasing frequency reuse potential.

Applications

Scientific research

This band is commonly used in radio astronomy and remote sensing. Ground-based radio astronomy is limited to high altitude sites such as Kitt Peak and Atacama Large Millimeter Array (ALMA) due to atmospheric absorption issues. Satellite-based remote sensing near 60 GHz can determine temperature in the upper atmosphere by measuring radiation emitted from oxygen molecules that is a function of temperature and pressure. The ITU non-exclusive passive frequency allocation at 57-59.3 is used for atmospheric monitoring in meteorological and climate sensing applications, and is important for these purposes due to the properties of oxygen absorption and emission in Earth’s atmosphere. Currently operational U.S. satellite sensors such as the Advanced Microwave Sounding Unit (AMSU) on one NASA satellite (Aqua) and four NOAA (15-18) satellites and the Special Sensor Microwave Imager Sounder (SSMI/S) on Department of Defense satellite F-16 make use of this frequency range.

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Rotation of LCD monitors

Poor side-viewing image quality of an LCD monitor rotated into portrait orientation.

Good side-viewing image quality of a typical landscape LCD.

Rotation of LCD monitors is easier and less complicated to do since the mass of the panel is low, the heat generated is low, and there are no magnetic effects to be concerned about. Many higher quality panels feature built in pivot points to allow the user to easily rotate the screen into portrait mode.

However, due to the light polarization technology an LCD monitor, the angle of image viewability will degrade when rotated. Liquid crystal displays vary in contrast when viewed from different angles along one axis. This axis is normally oriented to be vertical so that the image quality appears unchanged when the screen is viewed from the side, and image contrast is adjusted by tilting the panel up or down. By rotating the screen 90 degrees, the varying contrast axis is now horizontal and a viewer to one side will see a washed out light contrast image, while a viewer on the other side sees a very dark contrast image.

Rotation of projectors

Projectors can generally operate from any angle due to the compact, rigid design and a cooling system utilizing a forced-air fan. However for large heavy projectors the problem is how to mount the projector sideways, since nearly all ceiling mounts assume the projector hangs down from the mount in an upside-down landscape position. Extra-heavy bracing or weighted counter-balancing may be required to support a projector in a sideways portrait orientation. Projectors using an Hg-lamp (most of them, nowadays) should not be turned sideways as this shortens the lifespan of the bulb extremely.

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Modern arcade emulators are able to handle this difference in screen orientation by dynamically changing the screen resolution to allow the portrait oriented game to resize and fit a landscape display, showing wide empty black bars on the sides of the portrait-on-landscape screen.

Portrait orientation is still used occasionally within some arcade and home titles (either giving the option of using black bars or rotating the set), primarily in the vertical shoot 'em up genre due to considerations of aesthetics, tradition and gameplay.

Modern display rotation methods

Many modern video cards offer digital screen rotation capabilities. But in order for it to be used correctly, a special rotating display is required that is designed to be pivoted.

Rotation of CRT monitors

Very few CRT monitors made today are designed to permit rotation into portrait mode. It is not wise to turn a standard CRT monitor or television on its side due to a number of technical issues:

    * The cooling vents are normally designed for natural air convection flow from bottom to top; turning the case sideways can lead to unintended heat buildup and component failure.

    * The typical CRT monitor plastic case is not designed to sit stably when turned sideways without a custom-made supporting stand.

    * The weight of a large CRT is typically meant to bear on the base frame. A plastic case may flex or crack if the CRT weight is supported only by the thin plastic surround.

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For the first computing devices a screen was built to operate in only portrait or landscape mode, and changing between orientations was not possible. Typically a custom video controller board was needed to support the unusual screen orientation, and software often needed to be custom-written in order to support the tall, narrow screen layout.

As video display technology advanced, eventually the video display board was able to accommodate rotation of the display and a variety of differing resolutions and scan rates. After several years of producing the first Macintosh portrait display, Radius introduced the Radius Pivot CRT monitor, that could be freely rotated between landscape and portrait with automatic orientation changes done by the video controller.

Rotation is now a common feature of modern video cards, and is still sometimes used in tablet PCs, and by writers, layout artists, etc. Operating systems and drivers do not always support it; for example, Windows XP Service Pack 3 conflicts with monitor rotation on many graphics cards using ATI's Catalyst control software, Nvidia's proprietary drivers for Linux do not support screen rotation unless manual changes are made to its configuration.

Orientation of Video Game Displays

Portrait mode is popular with arcade games that involve a vertically oriented playing area, such as Pac Man and Donkey Kong. The vertical orientation allows greater detail along the vertical axis while conserving detail on the sides.

The conversion of early popular arcade games to home consoles was difficult not only because the home computing capability was lower, but also the screen orientation was wrong and the home user could not be expected to set their television on its side to show the game correctly. This is why most early home versions of arcade games have a wide, squashed appearance compared to the full-quality arcade versions.