What are Microwaves?
In an electromagnetic spectrum, we observe various electromagnetic waves having their frequency and wavelengths, one of them is the microwave. So, what does microwave mean and what type of wave is a microwave?
Microwaves are produced by special vacuum tubes, namely klystrons, magnetrons, and Gunn diodes and they have many real-life applications.
Reading further, we will learn about what are microwaves used for and what are microwaves made of.
Composition of Microwaves
Microwaves are electromagnetic radiations as UV rays, radio waves, and so on.
These waves have wavelengths ranging from one meter to one millimetre and the frequency ranging between 1 GHz and 1000 GHz.
Applications of Microwaves
Microwaves have many real-life applications, such as microwave ovens, radar systems, detecting the speed of objects like the speed of a tennis ball, automobile, and so on. Now, let’s discuss what are microwaves used for.
Telecommunication
Space communication, i.e., from earth to space, and vice-versa.
Intercontinental telephones and television.
In railways, microwaves are used for telemetry communication.
Industries
Microwaves are used in food processing industries.
Other industries where microwaves are used are Chemical industries, plastic industries, rubber industries, forest product-based industries, and so on.
Microwave ovens for heating the food items work at 2.45 GHz, 600 W.
Microwaves are used in man public works, breaking rocks, drying or breaking the concrete, and curing of cement, etc.
It is also used for drying grains, pharmaceuticals, textiles, leather.
Medical Field
Microwaves are employed for various diagnostic and therapeutic purposes.
They are used in electromagnetic heating for treating cancer patients (Hyperthermia for treating cancer).
Used for monitoring heartbeat and if someone is suffering from lung water problem, microwaves can detect the quantity of water in the lungs.
Microwaves are also used in diathermy for localized superficial heating.
Defence
Microwaves are used for tracking missiles, detecting aircraft and other flying objects.
Microwaves are also used for calculating the distance of objects and the speed of their flight.
A practical application of microwaves is the microwave oven. The cooking surface of the oven is composed of ceramic glass. Inside the oven, there are metallic magnetron tubes, the waveguide, and the stirring fan.
The electromechanical components and controls comprise timer motors, switches, and relays, etc.
The materials used for microwave cooking are:
Paper cups
Cartons
Cling films
Thermoplastics, etc.
Miscellaneous Microwave Applications
There are other places where we find the microwave uses. These are:
In Air Traffic control (ATC) to detect the movement of the airplane and manage the air traffic.
Police sped detectors.
To observe the movement of trains on rails while sitting in the microwave operated control room.
In defence, microwaves are used in radar systems for aircraft navigation.
A radar using microwaves can aid in detecting the speed of tennis balls, cricket balls, and automobiles in motion.
Observing and analyzing weather patterns.
Spread spectrum systems.
In garage door openers.
Burglar alarms.
In creating microwave devices like a microwave oven.
What is a Combination Microwave?
Combination microwaves or combi microwaves are kitchen appliances that are made by a combination of microwave energy, a grill, a fanned hot air (convection heating) for cooking the food.
Employing these two methods together creates a form of heat that can sauté, grill, bake, crisp, bring even roasting, and brown our food. It is the best method to obtain the speed of a microwave with the high-quality finish of regular oven cooking.
Application of Microwave Engineering
The microwave frequency ranges between 1 GHz and 300 GHz. These ranges are divided into a number of bands, which are symbolized by a letter.
Various organizations assign these bands a letter; however, the most common being employed is the IEEE Radar Bands followed by NATO Radio Bands and ITU Band.
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The frequency range is divided into portions and symbolized by an English alphabet, where each has its specific real-application of microwave engineering; let’s discuss these one-by-one:
1-2 GHz - L-Band - GSM, Marine satellite.
2-4 GHz - S-Band - Weather and surface ship radar, microwave oven, Bluetooth, Zeebee, Wi-Fi.
4-8 GHz - C-Band - These frequency range microwaves are used for satellite communication, Radar applications.
8-`12 GHz - X-Band - These frequency range microwaves are employed for satellite communications and educational purposes, microwave tubes for performing experiments in the lab.
12-18 GHz - Ku-Band - These microwaves are used in satellite TV and VSAT.
18-27 GHz - K-Band - RADAR, Armature satellite, infrared astronomy (to detect the intensity of stars and ascertain their distance, speed, and many other factors, we use K-band microwaves).
27-40 GHz - Ka-Band - Satellite communications, high resolution, and low-range RADAR, military airplane.
40-75 GHz - V-Band - High capacity terrestrial millimetre wave communications.
75-110 Gz - W-Band - Millimeter-wave RADAR and research. W-band is employed by ISRO, NASA, DRDO, and other agencies for research purposes.
110-300 GHz - mm (Millimetre) - Band - Millimeter-wave RADAR, satellite communications.
FAQs on Electromagnetic Spectrum Microwave
1. What are microwaves and where do they fit in the electromagnetic spectrum?
Microwaves are a type of electromagnetic radiation that fall between infrared radiation and radio waves on the electromagnetic spectrum. They are characterised by their shorter wavelengths compared to radio waves, which gives them unique properties for applications like heating and data transmission. Their position allows them to carry more information than radio waves of a similar aperture size.
2. What is the standard frequency and wavelength range of microwaves?
According to the CBSE/NCERT curriculum, microwaves typically have a frequency and wavelength range as follows:
- Frequency Range: Approximately 1 gigahertz (GHz) to 1000 gigahertz (GHz).
- Wavelength Range: Approximately 1 millimetre (mm) to 1 metre (m).
3. How are microwaves produced for use in devices like radar and ovens?
Microwaves are generated by specific types of vacuum tubes where the flow of electrons is controlled by magnetic or electric fields. The most common devices used for producing microwaves include:
- Magnetron tubes: Commonly used in microwave ovens.
- Klystron tubes: Used in radar systems and satellite communication.
- Gunn diodes: A semiconductor device used in microwave generators.
4. What are the most important applications of microwaves in modern technology?
Microwaves are essential in many areas of modern technology. Key applications include:
- Telecommunications: Used for long-distance telephone calls, television broadcasting, and satellite communication (including GPS).
- Radar Systems: Used in air traffic control, weather forecasting, and by police to detect speeding vehicles.
- Microwave Ovens: Used for cooking and reheating food through dielectric heating.
- Industrial Applications: Used for drying and curing materials in industries like rubber, plastics, and food processing.
5. Why are microwaves preferred over radio waves for radar systems?
Microwaves are preferred for radar systems due to their shorter wavelengths compared to radio waves. This property allows them to be focused into narrow beams, providing much higher resolution and directivity. A narrow beam can pinpoint the location, speed, and size of an object (like an aircraft or a storm cloud) with greater accuracy. Radio waves, with their longer wavelengths, would spread out more and require impractically large antennas to achieve the same level of focus.
6. How does a microwave oven use microwaves to heat food, and why do some containers remain cool?
A microwave oven heats food through a process called dielectric heating. It emits microwaves that cause polar molecules, primarily water, within the food to vibrate and rotate billions of times per second. This rapid rotation creates friction between the molecules, which generates thermal energy and heats the food. Containers made from microwave-safe materials like glass or certain plastics do not contain water or other polar molecules, so they do not absorb the microwave energy and remain relatively cool.
7. From a physics perspective, what are the potential biological effects of exposure to high-intensity microwave radiation?
The primary biological effect of high-intensity microwave radiation is thermal heating. Exposure can cause a significant rise in the temperature of body tissues. Certain parts of the body, such as the eyes and testes, are particularly vulnerable because they have low blood flow and cannot dissipate the excess heat effectively. This is why microwave-emitting devices are designed with shielding to prevent radiation leakage and ensure user safety as per regulated standards.
8. How do microwaves differ from radio waves in terms of their core properties?
The main differences between microwaves and radio waves lie in their frequency, wavelength, and how they propagate:
- Frequency and Wavelength: Microwaves have a higher frequency and shorter wavelength than radio waves.
- Bandwidth: Due to their higher frequency, microwaves have a larger bandwidth, allowing them to carry more data, which is ideal for high-speed communication.
- Propagation: Microwaves travel in straight lines (line-of-sight propagation) and are easily blocked by obstacles, whereas longer-wavelength radio waves can diffract around obstacles and travel over the horizon.
9. What is the importance of different microwave frequency bands like the C-band and Ku-band?
Different microwave frequency bands are allocated for specific applications to avoid interference and optimise performance. For example:
- S-Band (2-4 GHz): Used for weather radar, surface ship radar, and Wi-Fi because it is less affected by rain.
- C-Band (4-8 GHz): Widely used for satellite communication and TV broadcasting due to its balance of power and reliability against weather effects.
- X-Band (8-12 GHz): Used for military communications and high-resolution radar due to its fine detection capabilities.
- Ku-Band (12-18 GHz): Primarily used for satellite TV (like DTH services) and VSAT systems, offering a good compromise between antenna size and power.
