application of microwave

Application of a microwave

microwave tower

• Telecommunication:Intercontinental Telephone and T.V.,space communication(earth-to-space and space-earth),telemetry communication link for railways etc.
• radars:Detect aircraft,track/guide supersonic missiles,observe and track weather patterns,air traffic control(ATC),burglar alarms,garage door openers,police speed detectors etc.
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• commercial and industrial application use heat property of microwave:i)Microwave oven)(ii)Drying-machines-textile,food and paper industry for drying clothes, potato chips,printed matter etc.(iii)Rubber industry/plastics/chemical/forest product industries.(iv)mining/public works, breaking rock,tunnel boring,drying/breaking up concrete,breaking up coal seams,curing of cement.

• Electronic warfare: ECM/ECCM(Electronic counter measure/Electronic counter counter measure)systems,spread spectrum systems.

• Identifying object or personnel by non-contact method.
• Light generated charge carriers in a microwave semiconductor makes it possible to create a whole new world of microwave devices. 

             (i) microwave oven(2.45GHz,600W)

            (ii)Drying machines.

            (iii)food processing industry.

            (iv)Rubber industry/plastics/chemical/forest product   industries

microwave

MICROWAVE:  

Microwave are electromagnetic waves whose frequencies range from 1GHz to 1000GHz. for comparison,the signal from an AM radio station is 1 MHz and the signal from FM radio station is 100MHz.

microwave oven

microwave are also called since they are define in terms of their wavelength in the sense that micro refers to tinyness- tinyness referring to wavelength and the period of a cycle of a cm wave.

ADVANTAGE OF MICROWAVES

1.Increased bandwidth availability

 Microwaves have large band widths(1GHz-103 GHz) compared to the common bands namely MW,SW and UHF waves. the advantage of large bandwidths is that the frequency range of information channels will be a small percentage of the carrier frequency and more information can be transmitter in microwave frequency ranges. /microwave region is very useful since the lower band of frequency is already crowded.

2.Fading effect and reliability

Fading effect due to variation in the transmission medium is more efficient at low frequency. Due
to "Line of Sight"(LOS) propagation and high frequencies there is less fading effect and hence microwave communication is more reliable..

3.Power requirements

Transmitter/Receiver power requirements are pretty low at microwave frequencies compared to that at short wave band.  

pn diode

pn diode work
The term diode denotes a two-electrode device. A semiconductor diode is simply a P-N junction with connecting leads or terminals on the two sides of the P-N junctions.P-N junction is also called the crystal diode because the P-N junction is grown out of crystal. A  diode  is a unidirectional device permitting the easy flow of current in one direction but restraining the flow in opposite direction. A major application of diode is in rectification i.e., in conversion of ac into dc.semiconductor diode is becoming more and more popular these days due to its smaller size,cheapness,robustness and higher operating efficiency .
The p-type material of the diode is the positive electrode and is called the anode whereas the N-type material is the negative  electrode and is called the cathode. the arrow symbol used for the anode represents the direction of flow of conventional current. the electrode current flows in a direction opposite to the arrow.
The symbol for semiconductor diode in shown in figure Diodes have polarity and, therefore,must be connected in circuits in the correct direction.small diodes are marked with a band to indicate the cathode end. larger diode use the diode symbol to indicate their polarity.Diode  are available  in many package configuration,depending on their ratings.small diodes,used for low current application in circuits up to 1 A of average current,are generally packaged in a simple glass r plastic tube.Diodes for handling larger currents are packaged in metal containers and are often mounted by studs on metal plates to dissipate heat.
Diodes are rated in terms of their  peak and average forward current-carrying capability and in terms reverse voltage or peak inverse voltage ratings.None of these values can be exceeded,otherwise the diode will get damaged. For  the P-N diode junction,the reverse voltage rating applies to the instantaneous peak reverse voltage across the diode.
the diode junction can be viewed as an automatic switch that is closed when the p-type material is relatively negative .Remember,it is the voltage across the diode that is important not the voltage to another part of the circuit. because the depletion region is never completely absent,it takes a small voltage across a diode to make current flow,even when the polarity is correct for flow of larger current..
most diodes in use today make use of silicon semiconductor material;however,for some application, germanium is also used.

pn diode work in forward wise.when p terminal is connect to positive side of battery and n terminal is connect to a negative side of battery this is called a forward wise and it is active region. pn diode when on reverse wise then it got to saturation region.

Three type of region in pn junction diode:

• active region
• saturation region
• cut-off region 

picture of a diode


a diode there are two terminal  anode and cathode͢


gray line is cathode and all black area is anode