What is Microwave?
As the name suggests microwaves are very short waves whose electromagnetic spectrum lies in the frequency range from 300 MHz to 30 GHz. There are various bands under microwave frequency range. The bands are L Band ( 1 to 1.5GHz) , S band(1.5 to 3.9GHz) , C band ( 3.9 to 8GHz) , X band ( 8.2 to 12.5 GHz) , Ku band (12.5 to 18 GHz) and K band (18 to 26 GHz) .
The microwave communication and applications are increasing. It is used for satellite communication, navigation, radar, remote sensing and other short distance communication systems.
Due to following features of microwave , it has become very popular:
• As we know lower frequency bands are used by many applications such as radio, TV, telegraph and telephone. It is not possible to reuse these frequencies as it will create RF interference. This leads to use of microwave frequency bands. Microwaves offer higher frequency and larger bandwidth and multiple channels can be accommodated.
• To receive any EM wave, size of the antenna should be in the order of wavelength of the received EM wave. At low frequency wavelength will be larger while at high frequency it will be smaller and compact. This small size of the antenna leads to easy mounting or installation. Hence use of microwave will provide improvement in the antenna performance.
• Short wave communication leads to severe problem of fading mainly due to reflection of the EM wave from different layers of the ionosphere. As microwave is used for LOS (Line Of Sight) propagation based communication, it is not much affected by the ionosphere. This results into less effect of fading to the frequencies in the microwave band.
• As gain of the antenna is inversely proportional to the wavelength. Gain of the antenna will be high at higher frequency and less at lower frequency. Hence transmitter Power requirement at microwave band is less compare to short wave frequency.
• Microwave can generate heat energy. This property of microwave is used in biomedical engineering for the treatment of brain cancer, skin tightning, diathermy machine etc. It is used in microwave oven for cooking purpose. It is also used in drying machine and soldering purpose.
• It is used for remote sensing application to study the earth surface and terrain analysis. This is because microwave can easily penetrate in the earth.