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STRUCTURE OF AN ATOM THERE ARE 108 ELEMENTS IN NATURE

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Presentation on theme: "STRUCTURE OF AN ATOM THERE ARE 108 ELEMENTS IN NATURE"— Presentation transcript:

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2 STRUCTURE OF AN ATOM THERE ARE 108 ELEMENTS IN NATURE
ATOMS ARE THE SMALLEST PARTICLE OF AN ELEMENT THAT SHOWS ITS PROPERTIES. ATOMS ARE BUILDING BRICKS OF ALL MATTER AND MATTER IS ELECTRICAL IN NATURE. AN ATOM CONSIST OF : A) NUCLEUS B) ORBITS

3 BOHR’S ATOM

4 NUCLEUS PROTONS ( + ve CHARGE ) NEUTRONS ( NEUTRAL )
THE CENTRAL PART OF THE ATOM CONTAINS : PROTONS ( + ve CHARGE ) NEUTRONS ( NEUTRAL )

5 ORBITS OUTER PART OF THE ATOM CONTAINS ELECTRONS WHICH HAVE A - ve CHARGE. MASS OF ELECTRON IS NEGLIGIBLE. CHARGE IS EQUAL AND OPPOSITE TO THAT OF A PROTON. ATOMIC NO = NO OF PROTONS = NO OF ELECTRONS

6 APPROXIMATELY THAT OF P+
ATOM CONSTITUENT SYMBOL CHARGE MASS ELECTRONS E- -1 9.1 X G PROTONS P+ +1 1836 X ELECTRON MASS NEUTRONS N APPROXIMATELY THAT OF P+

7 VALENCE SHELL & FREE ELECTRONS
THE OUTER SHELL IS CALLED VALANCE SHELL. ELECTORNS IN OUTER SHELL ARE CALLED FREE ELECTRONS. THESE ELECTRONS IN OUTER SHELL CAN BE EASILY DISLODGED. THE NUMBER OF ELECTRONS WHICH CAN BE ACCOMODATED IN ANY ORBIT IS 2 N SQUARE, WHERE N IS NUMBER OF ORBIT. SO IN THIRD ORBIT WE CAN ACCOMMODATE 2 * 3 * 3 = 18 ELECTRONS

8 VALENCE SHELL & FREE ELECTRONS
IF THE OUTER SHELL THAT IS VALANCE SHELL CONTAINS MORE THAN FOUR ELECTRONS WE CALL IT CONDUCTOR. EXAMPLE IF THE OUTER SHELL THAT IS VALANCE SHELL CONTAINS LESS THAN FOUR ELECTRONS WE CALL IT INSULATOR. EXAMPLE IF THE OUTER SHELL THAT IS VALANCE SHELL CONTAINS MORE THAN FOUR ELECTRONS WE CALL IT SEMI CONDUCTOR. EXAMPLE

9 ELECTROMOTIVE FORCE FOR A CHARGE TO FLOW THROUGH, A CONDUCTOR REQUIRES A FORCE. THIS FORCE IS PROVIDED BY THE POTENTIAL DIFFERENCE APPLIED ACROSS THE TERMINALS.

10 ALTERNATING CURRENT THE CURRENT THAT PERIODICALLY CHANGES DIRECTION & CONTINUOUSLY CHANGES MAGNITUDE IT CAN BE PRODUCED BY : a) STATIONARY COIL AND MOVING MAGNETIC FIELD b) STATIONARY MAGNETIC FIELD AND MOVING COIL

11 THE ELECTROMAGNETIC SPECTRUM
THE ELECTROMAGNETIC SPECTRUM

12 THE ELECTROMAGNETIC SPECTRUM

13 THE VISIBLE SPECTRUM

14 SPECTRUM OF ELECTROMAGNETIC RADIATION
REGION λ (ANGS) (cm) C (HZ) ENERGY (EV) RADIO > 109 > 10 < 3 X 109 < 10-5 MICRO 3 X X 1012 INFRARED X 10-5 3 X X 1014 VISIBLE 7 X 10-5 – 4 X 10-5 4.3 X 1014 – 7.5 X 1014 2 - 3 UV 4 X 7.5 X X 1017 X-RAYS 3 X X 1019 GAMMA < 0.1 < 10-9 > 3 X 1019 > 105 SPECTRUM OF ELECTROMAGNETIC RADIATION

15 RADIO WAVES RADIO WAVE IS AN ELECTRO-MAGNETIC WAVE WHICH HAS ELECTRICAL AND MAGNETIC COMPONENT PERPENDICULAR TO EACH OTHER. IN FREE SPACE ALL RADIO WAVES & EM WAVES TRAVEL IN A STRAIGHT LINE AT THE SPEED OF LIGHT. ITS FREQUENCY IS FROM 3 K Hz TO 300 G Hz

16 Table of ITU Radio Bands
Symbols Frequency Range Wavelength Range Typical sources 1 ELF 3 to 30 Hz 10,000 to 100,000 km deeply-submerged submarine communication 2 SLF 30 to 300 Hz 1000 to 10,000 km submarine communication, ac power grids 3 ULF 300 to 3 kHz 100 to 1000 km earth quakes, earth mode communication 4 VLF 3 to 30 kHz 10 to 100 km near-surface submarine communication, 5 LF 30 to 300 kHz 1 to 10 km AM broadcasting, aircraft beacons 6 MF 300 to 3000 kHz 100 to 1000 m AM broadcasting, 7 HF 3 to 30 MHz 10 to 100 m Skywave long range radio communication 8 VHF 30 to 300 MHz 1 to 10 m FM radio broadcast, television broadcast, DVB-T, MRI 9 UHF 300 to 3000 MHz 10 to 100 cm microwave oven, television broadcast, GPS, mobile phone communication (GSM, UMTS, 3G, HSDPA), cordless phones (DECT), WLAN (Wi-Fi), Bluetooth 10 SHF 3 to 30 GHz 1 to 10 cm DBS satellite television broadcasting, WLAN (Wi-Fi), WiMAX, radars 11 EHF 30 to 300 GHz 1 to 10 mm directed-energy weapon (Active Denial System), Security screening (Millimeter wave scanner), intersatellite links, WiMAX, high resolution radar

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20 VLF  Very Low Frequency  3 kHz  30 kHz VF  Voice Frequency  300 Hz ELF  Extremely low Frequency  30 Hz ULF  Ultra Low Frequency  3 Hz

21 OSCILLATOR WAVES THE OSCILLATOR IS AN ELECTRONIC DEVICE FOR CREATING VOLTAGES THAT CAN BE MADE TO SURGE BACK AND FORTH AT WHATEVER FREQUENCY IS DESIRED WHEN RF ENERGY IS APPLIED TO A CONDUCTOR (ANTENNA), THE ANTENNA RESONATES (VIBRATES). THE ANTENNA PROVIDES A MEANS OF RADIATING THE ELECTROMAGNETIC (EM) WAVES INTO THE AIR

22 TYPES OF OSCILLATOR MASTER OSCILLATOR CRYSTAL OSCILLATOR
BEAT FREQUENCY OSCILLATOR LOCAL FREQUENCY OSCILLATOR

23 PHOTO OF OSCILLATOR

24 ELECTRICAL AND MAGNETIC FIELD
SPEED OF LIGHT = ELECTRICAL FIELD MAGNETIC FIELD THEREFORE MAGNETIC COMPONENT IS VERY SMALL

25 TERMS AND DEFINITIONS 1. CYCLE ONE COMPLETE SERIES OF VALUES OR ONE COMPLETE PROCESS, RETURNING TO VALUES OF ORIGIN. 2. FREQUENCY (f ) No OF CYCLES/SEC. UNITS ARE HERTZ. 1 Hz = 1 C/S, 1 K Hz = 10 C/S 1 M Hz = 10 C/S, 1 G Hz = 10 C/S

26 TERMS & DEFINITIONS CYCLE : ONE COMPLETE SERIES OF VALUES OR ONE COMPLETE PROCESS IS ONE CYCLE. WAVELENGTH : THE PHYSICAL DISTANCE TRAVELLED BY THE WAVE IN ONE CYCLE. AMPLITUDE : THE MAXIMUM DISPLACEMENT OF THE WAVE ABOUT ITS MEAN POSITION. FREQUENCY : THE NO OF CYCLES OCCURRING IN ONE SECOND.

27 RELATIONSHIP BETWEEN FREQUENCY WAVELENGTH
FREQUENCY ( f ) Hz = SPEED OF LIGHT ( c ) METERS/SEC WAVE LENGTH ( l ) METERS WAVE LENGTH ( l ) = SPEED OF LIGHT ( c ) METERS/SEC FREQUENCY ( f ) Hz

28 RELATIONSHIP BETWEEN FREQUENCY WAVELENGTH
FOR CALCULATION PURPOSE CONVERT FREQUENCY INTO METERS AND WAVE LENGTH INTO METERS UNIT OF FREQUENCY I CYCLE PER SECOND = 1 Hz 1000 Hz = 1 KILO Hz 1000 K Hz = 1 MEGA Hz 1000 M Hz = 1 GIGA Hz 100 CM = 1 METERS

29 RADIO SPECTRUM ABREVIATION FREQUENCY WAVELENGTH VLF K Hz km LF K Hz , m MF K Hz m HF M Hz m VHF M Hz m UHF M Hz cm SHF M Hz cm EHF MHz cm

30 PHASE THE INSTANTANEOUS POSITION OF A PARTICLE IN A WAVE OR POSITION OF A PARTICLE AT A GIVEN TIME TWO WAVES OF THE SAME FREQUENCY WHEN TRANSMITTED AT THE SAME TIME ARRIVE AT A POINT IN PHASE PHASE DIFFERENCE IS THE ANGULAR DIFFERENCE BETWEEN THE CORRESPONDING POINTS ON THE WAVEFORMS

31 PHASE 6. PHASE ANY STAGE IN THE CYCLE OF AC
7. PHASE DIFFERENCE IF TWO ACs OF OF THE SAME FREQUENCY (NOT NECESSARILY SAME AMPLITUDE) REACH SAME VALUE AT DIFFERENT INSTANTS OF TIME, THEY ARE SAID TO BE OUT OF PHASE DIFFERENCE IS THE ANGULAR DIFFERENCE IN THE CORRESPONDING POINTS OF THE WAVE FORMS AND IT IS MEASURABLE.

32 PHASE DIFFERENCE EXAMPLES

33 SPEED OF RADIO WAVES SPEED OF LIGHT IS 299,792,458 m/sec
WHICH IS APPROX = 3 X m/sec = 162,000 Nm/sec = 186,000 Sm/sec = 300,000 km/sec EFRACTIVE INDEX IS RATIO OF SPEED OF LIGHT IN A MEDIA AND SPEED OF LIGHT IN VACCUM SPEED OF RADIO WAVE IS MOST IN VACCUM SPEED OF RADIO WAVE IS MORE OVER WATER THAN LAND

34 POLAR DIAGRAM IT IS THE LINE JOINING POINTS OF EQUAL INTENSITY AT A GIVEN TIME. OR A LINE SO PLOTTED THAT IT GIVES THE RELATIVE VALUES OF THE FIELD STRENGTHS OR THE POWER RADIATED AT VARIOUS POINTS IN BOTH HORIZONTAL AND VERTICAL PLANES.

35 POLAR DIAGRAM

36 POLARIZATION ELECTRICAL AND MAGNETIC FIELDS ARE PRODUCED WHEN E/M WAVES TRAVEL THROUGH SPACE THESE FIELDS ARE AT RIGHT ANGLES TO EACH OTHER A VERTICAL AERIAL TRANSMITS THE ELECTRICAL FIELD IN A VERTICAL PLANE

37 ANTENNAS ARE DESIGNED TO PICK UP ELECTRICAL COMPONENT ONLY
POLARISATION POLARISATION ANTENNAS ARE DESIGNED TO PICK UP ELECTRICAL COMPONENT ONLY

38 MODULATION PROCESS OF IMPRESSING INTELLIGENCE ON A RADIO CARRIER WAVE (CW) IN ORDER TO CONVEY INFORMATION VARIOUS TYPE OF MODULATION ARE (a) KEYING (b) AMPLITUDE MODULATION (c) FREQUENCY MODULATION (d) PULSE MODULATION

39 NEED FOR MODULATION 1. PRACTICAL ANTENNA HEIGHT: LOWER THE FREQUENCY LARGER THE ANTENNA. 2. OPERATING RANGE : LOWER THE FREQUENCY LOWER THE RANGE. 3. WIRELESS COMMUNICATION : AUDIO FREQUENCIES WHEN TRANSMITTED THROUGH SPACE GET ATTENUATED.

40 TYPES OF MODULATION AMPLITUDE MODULATION FREQUENCY MODULATION PULSE MODULATION

41 AMPLITUDE MODULATION THE AMPLITUDE OF THE CARRIER IS CHANGED IN ACCORDANCE WITH THE INTENSITY OF THE SIGNAL THE FREQUENCY OF THE CARRIER WAVE IS KEPT CONSTANT

42 AMPLITUDE MODULATION

43 AMPLITUDE MODULATION (AM)

44 MODULATION DEPTH THE RATIO OF THE AMPLITUDES OF THE SIGNAL TO THE UNMODULATED CARRIER WAVE EXPRESSED IN PERCENTAGE MOD. DEPTH = AMPLITUDE OF SIGNAL *100 AMPLITUDE OF CW

45 TEMPORAL REPRESENTATIONS OF DSB-AM SIGNALS

46 IMPORTANCE OF MOD. DEPTH
IF DEPTH LESS THAN 50% - AUDIO SIGNALS NOT VERY STRONG 2. IF DEPTH MORE THAN 75% - AUDIO SIGNALS ARE STRONG AND CLEAR 3. IF DEPTH MORE THAN 100% - DISTORTION IN RECEPTION & WASTAGE OF POWER GREATER THE MODULATION, LESSER THE RANGE

47 FREQUENCY MODULATION THE FREQUENCY OF THE CARRIER IS CHANGED IN ACCORDANCE WITH THE INTENSITY OF THE AF SIGNAL THE AMPLITUDE OF THE CARRIER WAVE IS KEPT CONSTANT

48 FM

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50 ADVANTAGES OF FM 1. NOISELESS RECEPTION 2. HIGH EFFICIENCY
3. HI-FI RECEPTION.

51 DISADVANTAGES OF FM 1. COMPLICATED RECEIVERS
2. OPERATES ON VHF, HENCE RANGE IS LESS.

52 COMPARISON OF AM AND FM AM FM 1. TRANSMITTER COMPLEX SIMPLE 2. RECEIVER SIMPLE COMPLEX 3. STATIC EXCESSIVE ALMOST NIL 4. BAND WIDTH SMALL LARGE 5. POWER FOR TX LARGE SMALL

53 SIDE BANDS WHENEVER A CONTINUOUS WAVE IS MODULATED BY A FREQUENCY LOWER THAN ITSELF, ADDITIONAL FREQUENCIES OCCUR ON EITHER SIDE OF THE CW FREQUENCY THESE ARE CALLED SIDE BANDS. THE INTELLIGENCE IS CARRIED IN THESE SIDE BANDS.

54 AM CW COMPRISES OF CW FREQ CW FREQ + AUDIO FREQ CW FREQ - AUDIO FREQ

55 AM CW SIDEBANDS

56 SPECTRAL REPRESENTATIONS OF DSB-AM SIGNALS

57 SINGLE SIDE BANDS ADVANTAGES
(a ) LESSER FREQUENCY SPACE REQUIRED RESULTING IN LESSER CONGESTION (b ) LESSER POWER REQUIRED. GREATER RANGES

58 FM CW LARGER BAND WIDTH DUE MULTIPLE SIDE BANDS. THIS IS WHY FM CW CAN OPERATE MAINLY IN VHF BAND.

59 FM CW

60 PULSE MODULATION PHASE MODULATION CONSISTS OF PULSE AMPLITUDE
PULSE FREQUENCY PULSE WIDTH MAINLY USED IN RADARS

61 ELECTROMAGNETIC WAVES
WHEN WAVES MEET A BOUNDARY, WHERE THE MEDIUM CHANGES, THEY MAY: REFLECT - BOUNCE BACK REFRACT - GO THROUGH THE BOUNDARY, USUALLY CHANGING SPEED AND DIRECTION GET ABSORBED - GIVE UP THEIR ENERGY, WARMING UP THE SURFACE LAYER

62 DIFFRACTION WHEN WAVES MEET A GAP IN A BARRIER, THEY CARRY ON THROUGH THE GAP. THIS MAY SEEM OBVIOUS, BUT WHAT HAPPENS ON THE FAR SIDE OF THE GAP ISN'T SO STRAIGHTFORWARD. THE WAVES ALWAYS 'LEAK' TO SOME EXTENT INTO THE SHADOW AREA BEYOND THE GAP. THIS IS CALLED DIFFRACTION THE EXTENT OF THE SPREADING DEPENDS ON HOW THE WIDTH OF THE GAP COMPARES TO THE WAVELENGTH OF THE WAVES

63 GENERAL PROPERTIES OF RADIO WAVES
IN A GIVEN MEDIUM, RADIO WAVES TRAVEL AT A CONSTANT SPEED. (FREE SPACE - 3 X M/S) WHEN PASSING FROM ONE MEDIUM TO ANOTHER OF DIFFERENT REFRACTIVE INDEX THE VELOCITY OF THE WAVES CHANGES. THEY ARE ALSO DEFLECTED TOWARDS THE MEDIUM OF HIGHER REFRACTIVE INDEX RADIO WAVES ARE REFLECTED BY OBJECTS COMMENSURATE WITH WAVELENGTHS. UNINFLUENCED. RADIO WAVES TRAVEL IN STRAIGHT LINES.

64 GROUND WAVES SKY WAVES TYPES OF RADIO WAVES SURFACE WAVES SPACE WAVES
DIRECT WAVES GROUND REFLECTED WAVES

65 RADIO SPECTRUM ABREVIATION FREQUENCY WAVELENGTH VLF K Hz km LF K Hz , m MF K Hz m HF M Hz m VHF M Hz m UHF M Hz cm SHF M Hz cm EHF MHz cm

66 SURFACE WAVES DIFFRACTION DIFFRACTION FREQUENCY

67 SURFACE WAVES ATTENUATION FACTORS SURFACE FREQUENCY ATTENUATION

68 SURFACE WAVES

69 SUMMARY OF GROUND RANGES FROM RADIO WAVES
ATTENUATION DIFFRACTION RANGE VLF LEAST MAXIMUM nm LF LESS REDUCING ~ 1500 nm MF INCREASING REDUCING nm LAND ~1000 nm OVER SEA HF SEVERE LEAST nm VHF NIL LOS ONLY ABOVE ALONG SURFACE

70 DISADVANTAGES OF LOW FREQUENCIES
LOW EFFICIENCY AERIALS SEVERE STATIC HIGH INSTALLATION COST AND POWER REQT

71 SPACE WAVES REFRACTIVE INDEX ( n ) OF ATMOSPHERE IS A FUNCTION OF PRESSURE, TEMP & HUMIDITY AS ALT INCREASES, n REDUCES. AS A RESULT, WAVES REFRACT TOWARDS EARTH CAUSING RANGE TO INCREASE D = HT HR

72 DUCT PROPAGATION / SUPERREFRACTION

73 IONOSPHERE U/V RAYS ELECTRONS GAS MOLECULES
POSITIVE IONS : TOO HEAVY TO INFLUENCE LEVEL OF IONISATION : EXTENT OF REFRACTION

74 PROPAGATION : SKY WAVES
THE IONOSPHERE ELECRICALLY CONDUCTING SPHERE D LAYER : KM, AVG 75 KM E LAYER : KM, AVG 125 KM F LAYER : KM, AVG 225 KM

75 DENSITY OF IONOSPHERE D LEAST , F MAXIMUM DIURNAL ACTIVITY : DAY -- DENSITY INCREASES REFLECTING HT MOVES DN SEASONAL ACTIVITY : MAX -- EARTH CLOSEST TO SUN. CAUSES SPORADIC ACTIVITY, RESULTING IN “SPORADIC-E” RECEPTION IN VHF BAND (~150 MHz ) 11 YEAR SUN-SPOT CYCLE : ENHANCED UV & X-RADIATION, VHF SIGNALS MAY RETURN

76 11 YEAR SUNSPOT CYCLE

77 ATTENUATION IN ATMOSPHERE
DENSITY OF LAYERS : GREATER DENSITY -- GREATER ATTENUATION FREQ IN USE LOWER FREQ -- GREATER ATTENUATION PENETRATION DEPTH HIGHER THE FREQ -- GREATER THE PENETRATION-GREATER ATTENUATION

78 RANGES AVAILABLE TRANSMISSION POWER DEPTH OF PENETRATION
ANGLE OF INCIDENCE -- MAX RANGE BY WAVE LEAVING TANGENTIAL TO EARTH

79 CRITICAL ANGLE α2 α1 FOR A GIVEN FREQUENCY AS THE ANGLE OF INCIDENCE IS INCREASED, DEGREE OF REFRACTION INCREASES SUCH THAT AN ANGLE IS REACHED WHERE TIR TAKES PLACE α2 IS THE CRITICAL ANGLE

80 CRITICAL ANGLE α2 α1 FOR THE SAME FREQUENCY AN INCREASE IN INCIDENCE BEYOND α2 WOULD ENSURE AN UNINTERRUPTED RETURN ALTHOUGH POWER MAY HAVE TO BE INCREASED IF THE FREQUENCY WERE INCREASED AT α2 , THE CRITICAL ANGLE WOULD INCREASE AS THE WAVES WOULD TEND TO ESCAPE (DUE TO HIGHER ELECTRON DENSITY AND LOWER INCIDENCE REQUIREMENT) THIS ALSO MEANS A HIGHER RANGE WOULD BE OBTAINED.

81 HF COMMUNICATION MUF = fC X sec θi LUHF
CRITICAL FREQUENCY fC FOR PREVAILING ATMOSPHERIC CONDITIONS MUF = fC X sec θi LUHF

82 NIGHT TRANSMISSION RANGES AT NIGHT ARE GREATER THAN DAY TIME
IONIZATION LAYER HT DEPTH OF PENETRATION

83 NIGHT TRANSMISSION RANGE INCREASES, GREATER SKIP DISTANCE
RECOMBINATION REFLECTING HT MOVES UP RANGE INCREASES, GREATER SKIP DISTANCE

84 Table of ITU Radio Bands
Band Number Symbols Frequency Range Wavelength Range Typical sources 1 ELF 3 to 30 Hz 10,000 to 100,000 km deeply-submerged submarine communication 2 SLF 30 to 300 Hz 1000 to 10,000 km submarine communication, ac power grids 3 ULF 300 to 3 kHz 100 to 1000 km earth quakes, earth mode communication 4 VLF 3 to 30 kHz 10 to 100 km near-surface submarine communication, 5 LF 30 to 300 kHz 1 to 10 km AM broadcasting, aircraft beacons 6 MF 300 to 3000 kHz 100 to 1000 m AM broadcasting, 7 HF 3 to 30 MHz 10 to 100 m Skywave long range radio communication 8 VHF 30 to 300 MHz 1 to 10 m FM radio broadcast, television broadcast, DVB-T, MRI 9 UHF 300 to 3000 MHz 10 to 100 cm microwave oven, television broadcast, GPS, mobile phone communication (GSM, UMTS, 3G, HSDPA), cordless phones (DECT), WLAN (Wi-Fi), Bluetooth 10 SHF 3 to 30 GHz 1 to 10 cm DBS satellite television broadcasting, WLAN (Wi-Fi), WiMAX, radars 11 EHF 30 to 300 GHz 1 to 10 mm directed-energy weapon (Active Denial System), Security screening (Millimeter wave scanner), intersatellite links, WiMAX, high resolution radar

85 NIGHT TRANSMISSION LOWERING OF FREQUENCY ADJUSTS SKIP DISTANCE
LOWER FREQUENCIES REFLECT FROM LOWER HTS REQUIRE SMALLER CRITICAL ANGLE

86 SKIP DISTANCE AND DEAD SPACE
FOR A GIVEN FREQ, SKIP DIST VARIOUS WITH TIME OF THE DAY ( AND ALSO SEASONS) DEAD SPACE POSSIBLE ONLY IN HF

87 VLF  Very Low Frequency  3 kHz  30 kHz VF  Voice Frequency  300 Hz ELF  Extremely low Frequency  30 Hz ULF  Ultra Low Frequency  3 Hz

88 ANTANNAE An antenna (or aerial) is a transducer designed to transmit or receive electromagnetic waves. In other words, antennas convert electromagnetic waves into electrical currents and vice versa. They are used with waves in the radio part of the electromagnetic spectrum, that is, radio waves, and are a necessary part of all radio equipment. They are used with waves in the radio part of the electromagnetic spectrum, that is, radio waves, and are a BEGINNING OR END all radio equipment.

89 An antenna (or aerial) is a transducer designed to transmit or receive electromagnetic waves. In other words, antennas convert electromagnetic waves into electrical currents and vice versa. They are used with waves in the radio part of the electromagnetic spectrum, that is, radio waves, and are a necessary part of all radio equipment.

90 1.                  Atannae gain is ratio between radiation intensity in a given direction and that produced by an ideal antannae which transmits in all direction. What is loop antannae with two arms used in ADF 2.                  EIRP stands for effective isotropically radiated power. it is the amount of power that a theoretical isotropical antennae would emit to produce peak power in direction of maximum antannae gain. EIRP = power at transmitter - cable loss + antannae gain

91 microphone

92 speaker

93 TRANSMITTER BLOCK DIAGRAM
ANTANNAE RADIATES RF+AF OSCILLATOR PRODUCES RF RF AMPLIFIER AMPILFIES RF MODULATOR MODULATES RF WITH AF POWER AMPLIFIER AMPLIFIES RF+AF MICROPHONE CONVERTS AW TO AF AF AMPLIFIER AMPLIFIES AF

94 RECEIVER BLOCK DIAGRAM
ANTANNAE RECEIVES RF+AF SPEAKER CONVERTS AF INTO AW DEMODULATOR SUPRESSES RF AND PRODUCES AF AMPLIFIER AMPLIFIES RF+AF AF AMPLIFIER AMPLIFIES AF

95 SUPERHETORDYNE RECEIVER BLOCK DIAGRAM
ANTANNAE RECEIVES RF+AF 8500 K Hz AMPLIFIER AMPLIFIES RF+AF SPEAKER CONVERTS AF INTO AW MIXER MIXES RF+AF AND LF AND PRODUCES IF 500 K Hz DETECTOR CONVERTS IF INTO AF AF AMPLIFIER AMPLIFIES AF BFO AVC SQUELCH LF AMPLIFIERS AMPLIFIES LF LFO PRODUCES LF 8000 K Hz

96 Tuned frequency reciever

97 Qualities of reciever

98 superhetrodyne

99


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