What is the wavelength of a microwave?
Microwave is a form of electromagnetic radiation with wavelengths ranging from about one meter to one millimeter corresponding to frequencies between 300 MHz and 300 GHz respectively.
What frequency does a microwave absorb?
Beginning at about 40 GHz, atmospheric gases also begin to absorb microwaves, so above this frequency microwave transmission is limited to a few kilometers. A spectral band structure causes absorption peaks at specific frequencies (see graph at right).
How far can a microwave travel?
Microwaves travel by line-of-sight; unlike lower frequency radio waves they do not diffract around hills, follow the earth's surface as ground waves, or reflect from the ionosphere, so terrestrial microwave communication links are limited by the visual horizon to about 40 miles (64 km).
How far can a microwave beam be from the troposphere?
This technique has been used at frequencies between 0.45 and 5 GHz in tropospheric scatter (troposcatter) communication systems to communicate beyond the horizon, at distances up to 300 km.
What is the name of the metal pipe used to carry radio waves?
At microwave frequencies, the transmission lines which are used to carry lower frequency radio waves to and from antennas, such as coaxial cable and parallel wire lines, have excessive power losses, so when low attenuation is required microwaves are carried by metal pipes called waveguides.
How do microwaves work?
This means that they work on the basis of clumps of electrons flying ballistically through them, rather than using a continuous stream of electrons. Low-power microwave sources use solid-state devices such as the field-effect transistor (at least at lower frequencies), tunnel diodes, Gunn diodes, and IMPATT diodes.
What does the prefix "micro" mean?
The prefix micro- in microwave is not meant to suggest a wavelength in the micrometer range. Rather, it indicates that microwaves are "small" (having shorter wavelengths), compared to the radio waves used prior to microwave technology.
Standard Microwave Size
In choosing your next standard countertop microwave, there are two measurements you need to consider.
Different Microwave Dimensions
There are different countertop microwave sizes, and some fit for the smaller kitchen, while there are also microwaves with bigger internal capacity.
Over the Range Microwave Sizes
An over-the-range microwave can be affixed over your stove and installed as a part of your kitchen cupboards. Over-the-range microwaves will make your kitchen look clean and stationary, especially if you are going for a matching stovetop and over-the-range microwave combo.
Are All Over The Range Microwaves The Same Size?
Over-the-range microwaves come in a variety of sizes and dimensions, but the usual interior capacity ranges from 0.8 to 2.1 cubic feet.
Standard Microwave Size Over Range
Standard Over-the-range microwaves have dimensions of 30 inches or 76.2 centimeters in width, a height from top to bottom of 17 inches or 43.18 centimeters, and a depth of 15 to 18 inches or 38.1 to 45.72 centimeters.
Built-in Microwave Sizes
Built-in microwaves are constructed to fit in the wall or surrounded by overhead cabinetry. This will allow for more counter space and add to the overall aesthetics of your kitchen. Built-in microwaves can open from the side, but they could also be pulled down like an oven.
Microwave Cabinet Size
You need to take note of a few specific measurements, especially if you are looking to install an over-the-range or a built-in microwave for your kitchen.
What is the difference between a microwave and a radio?
Microwaves are a portion or "band" found at the higher frequency end of the radio spectrum , but they are commonly distinguished from radio waves because of the technologies used to access them. Different wavelengths of microwaves (grouped into "sub-bands") provide different information to scientists.
What are microwaves used for?
Microwaves that penetrate haze, light rain and snow, clouds, and smoke are beneficial for satellite communication and studying the Earth from space. The SeaWinds instrument onboard the Quick Scatterometer (QuikSCAT) satellite uses radar pulses in the Ku-band of the microwave spectrum.
How does a microwave work?
Microwave ovens work by using microwave about 12 centimeters in length to force water and fat molecules in food to rotate. The interaction of these molecules undergoing forced rotation creates heat, and the food is cooked.
What wavelength does the ERS-1 satellite send?
LEFT: The ERS-1 satellite sends out wavelengths about 5.7 cm long (C-band).This image shows sea ice breaking off the shores of Alaska. CENTER: The JERS satellite uses wavelengths about 20 cm in length (L-band).This is an image of the Amazon River in Brazil. RIGHT: This is a radar image acquired from the Space Shuttle. It also used awavelengthin the L-band of the microwave spectrum. Here we see a computerenhanced radarimage of some mountains on the edge of Salt Lake City, Utah.
What band microwaves are used in cars?
L-band microwaves, like those used by a Global Positioning System (GPS) receiver in your car, can also penetrate the canopy cover of forests to measure the soil moisture of rain forests. Most communication satellites use C-, X-, and Ku-bands to send signals to a ground station.
Overview
Microwave uses
Microwave technology is extensively used for point-to-point telecommunications (i.e. non-broadcast uses). Microwaves are especially suitable for this use since they are more easily focused into narrower beams than radio waves, allowing frequency reuse; their comparatively higher frequencies allow broad bandwidth and high data transmission rates, and antenna sizes are smaller than at lower …
Propagation
Microwaves travel solely by line-of-sight paths; unlike lower frequency radio waves, they do not travel as ground waves which follow the contour of the Earth, or reflect off the ionosphere (skywaves). Although at the low end of the band they can pass through building walls enough for useful reception, usually rights of way cleared to the first Fresnel zone are required. Therefore, on the surface …
Antennas
The short wavelengths of microwaves allow omnidirectional antennas for portable devices to be made very small, from 1 to 20 centimeters long, so microwave frequencies are widely used for wireless devices such as cell phones, cordless phones, and wireless LANs (Wi-Fi) access for laptops, and Bluetooth earphones. Antennas used include short whip antennas, rubber ducky antennas, sleeve dipo…
Design and analysis
The term microwave also has a more technical meaning in electromagnetics and circuit theory. Apparatus and techniques may be described qualitatively as "microwave" when the wavelengths of signals are roughly the same as the dimensions of the circuit, so that lumped-element circuit theory is inaccurate, and instead distributed circuit elements and transmission-line theory are more useful methods for design and analysis.
Microwave sources
High-power microwave sources use specialized vacuum tubes to generate microwaves. These devices operate on different principles from low-frequency vacuum tubes, using the ballistic motion of electrons in a vacuum under the influence of controlling electric or magnetic fields, and include the magnetron (used in microwave ovens), klystron, traveling-wave tube (TWT), and gyrotron. Th…
Microwave frequency bands
Bands of frequencies in the microwave spectrum are designated by letters. Unfortunately, there are several incompatible band designation systems, and even within a system the frequency ranges corresponding to some of the letters vary somewhat between different application fields. The letter system had its origin in World War 2 in a top secret U.S. classification of bands used in radar sets; this is the origin of the oldest letter system, the IEEE radar bands. One set of microwa…
Microwave frequency measurement
Microwave frequency can be measured by either electronic or mechanical techniques.
Frequency counters or high frequency heterodyne systems can be used. Here the unknown frequency is compared with harmonics of a known lower frequency by use of a low-frequency generator, a harmonic generator and a mixer. The accu…