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1. Elkom dan Gelombang
Mikro

2. Materi
 Pengantar Elektronika Komunikasi
 Modulasi Amplituda
 Modulasi Frekuensi dan Phasa
 Radio Pemancar dan Penerima
 Pengantar system komunikasi gelombang mikro
 Saluran Transmisi
 Resonator dan Filter Sistem komunikasi Gelombang Mikro
 Amplifier dan Osilator Sistem komunikasi Gelombang Mikro
 Rangkaian Aktif Gelombang Mikro

3. Referensi
 Louis Frenzel, “Electronic Communication System”, Mc Graw Hill, 2016
 Richard A. Poisel “Introduction to Communication Electronic Warfare Systems” -
Artech Print on Demand (2002)
 Dennis Roddy, “Microwave Technology”, Reston Pub Co (January 1, 1986)
 Donna Reiss, Dickie Selfe, Art Young, “Electronic Communication Across the
Curriculum” , National Council of Teachers of English (1998)

4. Aturan Kuliah
 Datang Tepat waktu
 Kumpul Tugas Tepat Waktu
 Minimal 13 pertemuan
 Sakit / ijin : ada keterangan

5. Penilaian
 Kuis + Tugas : 15%
 Softskill : 25%
 UTS : 30%
 UAS : 30%

6. Pendahuluan
 What is communication?
 Communication is the process of exchanging information. People communicate to
convey their thoughts, ideas, and feelings to others.
 The process of communication is inherent to all human life and includes verbal,
nonverbal (body language), print, and electronic processes.
 Hambatan? Distance
Language

7. Pendahuluan cont’
 For many years, long-distance communication was limited to the sending of verbal
or written messages by human runner, horseback, ship, and later trains.
 Human communication took a dramatic leap forward in the late nineteenth century
when electricity was discovered.
 The telegraph was invented in 1844 and the telephone in 1876. Radio was discovered in
1887 and demonstrated in 1895

8. Pendahuluan Cont’
A general model of all communication systems

9. Transmitter
 The transmitter is a collection of electronic components and circuits designed to
convert the electrical signal to a signal suitable for transmission over a given
communication medium.
 Transmitters are made up of oscillators, amplifiers, tuned circuits and filters, modulators, frequency
mixers, frequency synthesizers, and other circuits
 The first step in sending a message is to convert it into electronic form suitable for
transmission.
 Transducers convert physical characteristics (temperature, pressure, light intensity, and
so on) into electrical signals.

10. Channel
 The communication channel is the medium by which the electronic
signal is sent from one place to another.
 Many different types of media are used in communication
systems, including wire conductors, fiber-optic cable, and free space.
 Alternating-current (ac) power lines, the electrical conductors that
carry the power to operate virtually all our electrical and
electronic devices, can also be used as communication
channels

11. Receivers
A receiver is a collection of electronic components and
circuits that accepts the transmitted message from
the channel and converts it back to a form
understandable by humans.
Receivers contain amplifiers, oscillators, mixers, tuned
circuits and filters, and a demodulator or detector
that recovers the original intelligence signal from the
modulated carrier.

12. Transceivers
If Electronic communication is two-way, so both
parties must have both a transmitter and a receiver.
As a result, most communication equipment
incorporates circuits that both send and receive.
Telephones, handheld radios, cellular telephones, and
computer modems are examples of transceivers.

13. Attenuation
Signal attenuation, or degradation, is
inevitable no matter what the medium of
transmission.
Attenuation is proportional to the square of
the distance between the transmitter and
receiver.

14. Noise
The measure of noise is usually expressed in terms of
the signal-to-noise (S/N) ratio (SNR), which is the
signal power divided by the noise power and can be
stated numerically or in terms of decibels (dB).
Obviously, a very high SNR is preferred for best
performance.

15. Types of Electronic Communication

16. Duplex

17. Analog Signals vs Digital Signals

18. Modulation and Multiplexing
 Modulation makes the information signal more compatible with the medium.
 Multiplexing allows more than one signal to be transmitted concurrently over a single
medium
 Whether the original information or intelligence signals are analog or digital, they are all
referred to as baseband signals
 baseband information signals can be sent directly and unmodified over the medium or
can be used to modulate a carrier for transmission over the medium.
 Normally used to modulate a high-frequency signal called a carrier.
 The electromagnetic signals, which are able to travel through space for long distances,
are also referred to as radio-frequency (RF) waves, or just radio waves

19. Broadband Transmission
 This process is called broadband transmission

20.  The carrier is usually a sine wave generated by an oscillator.
 The carrier is fed to a circuit called a modulator along with the baseband
intelligence signal.
 The intelligence signal changes the carrier in a unique way.
 The modulated carrier is amplified and sent to the antenna for transmission.
 Consider the common mathematical expression for a sine wave:

21.  Types of modulation. (a) Amplitude modulation. (b) Frequency modulation

22.  The three ways to make the baseband signal change the carrier sine wave are to
vary its amplitude, vary its frequency, or vary its phase angle.
 Varying the phase angle produces phase modulation (PM).
 Phase modulation produces frequency modulation; therefore, the PM signal is
similar in appearance to a frequency-modulated carrier.
 FSK and PSK

23. Multiplexing
 Multiplexing is the process of allowing two or more signals to share the same medium
or channel.
 A multiplexer converts the individual baseband signals to a composite signal that is
used to modulate a carrier in the transmitter.
 There are three basic types of multiplexing: frequency division, time division, and code
division.
 In frequency-division multiplexing, the intelligence signals modulate subcarriers on
different frequencies that are then added together, and the composite signal is used to
modulate the carrier.
 In optical networking, wavelength division multiplexing (WDM) is equivalent to
frequency-division multiplexing for optical signal.
 In code-division multiplexing, the signals to be transmitted are converted to digital data
that is then uniquely coded with a faster binary code. The signals modulate a carrier on
the same frequency. All use the same communications channel simultaneously. The
unique coding is used at the receiver to select the desired signal

25. Frequency and Wavelength
 Frequency is the number of cycles of a repetitive wave that occurs in a given time
period.

26.  The electromagnetic spectrum used in electronic communication.

28. Bandwidth
 Bandwidth (BW) is that portion of the electromagnetic spectrum occupied by a
signal.
 It is also the frequency range over which a receiver or other electronic circuit
operates.
 More specifically, bandwidth is the difference between the upper and lower
frequency limits of the signal or the equipment operation range.
 The upper frequency is f2 and the lower frequency is f1.
 The bandwidth, then, is

29. Channel Bandwidth
 The modulation process causes other signals, called sidebands, to be generated at
frequencies above and below the carrier frequency by an amount equal to the
modulating frequency.
 In other words, the modulation process generates other signals that take up spectrum
space.
 For example, in AM broadcasting, audio signals up to 5 kHz can be transmitted. If the
carrier frequency is 1000 kHz, or 1 MHz, and the modulating frequency is 5 kHz,
sidebands will be produced at 1000 - 5 = 995 kHz and at 1000 + 5 = 1005 kHz.
 The term channel bandwidth refers to the range of frequencies required to transmit the
desired information.
 So the channel bandwidth from example above become difference between the highest
and lowest transmitting frequencies: BW =1005 kHz - 995 kHz =10 kHz. In this case, the
channel bandwidth is 10 kHz.

30. Gain, Attenuation, and Decibels
 Gain means amplification

31. Example

32. Attenuation
 Attenuation refers to a loss introduced by a circuit or component.
 If the output signal is lower in amplitude than the input, the circuit has loss, or
attenuation.

33. Attenuation Cont’
 It is common in communication systems and equipment to cascade circuits and
components that have gain and attenuation

34. Decibels
 The gain or loss of a circuit is usually expressed in decibels (dB), a unit of
measurement that was originally created as a way of expressing the hearing
response of the human ear to various sound levels

36. Decibel Calculations
 Remember that the logarithm y of a number N is the power to which the base 10
must be raised to get the number.

37. Example
a. An amplifier has an input of 3 mV and an output of 5 V. What is the gain in
decibels?
b. A filter has a power input of 50 mW and an output of 2 mW. What is the gain or
attenuation?
c. A power amplifier with a 40-dB gain has an output power of 100 W. What is the
input power?
d. An amplifier has a gain of 60 dB. If the input voltage is 50 μV, what is the output
voltage?

38. dBm
 When an absolute value is needed, you can use a reference value to compare any
other value.
 Here Pout is the output power, or some power value you want to compare to 1
mW, and 0.001 is 1 mW expressed in watts.
 The output of a 1-W amplifier expressed in dBm is
 -50 dBm ?

39. Example
 A power amplifier has an input of 90 mV across 10 kV. The output is 7.8 V across an
8-V speaker. What is the power gain, in decibels?
 Hint : You must compute the input and output power levels first.

40. dBc
 This is a decibel gain attenuation figure where the reference is the carrier.
 For example, if the spurious signal is 1 mW compared to the 10-W carrier, the dBc
is :

41. Example
 An amplifier has a power gain of 28 dB. The input power is 36 mW. What is the
output power?
 A circuit consists of two amplifiers with gains of 6.8 and 14.3 dB and two filters with
attenuations of 216.4 and 22.9 dB. If the output voltage is 800 mV, what is the input
voltage?
 Express Pout 5 12.3 dBm in watts ?

42. Tuned Circuits
 Circuits made up of inductors and capacitors that resonate at specific frequencies
 All tuned circuits and many filters are made up of inductive and capacitive
elements, including discrete components such as coils and capacitors and the stray
and distributed inductance and capacitance that appear in all electronic circuits.
 Both coils and capacitors offer an opposition to alternating-current flow known as
reactance, which is expressed in ohms.
 Like resistance, reactance is an opposition that directly affects the amount of
current in a circuit.
 In addition, reactive effects produce a phase shift between the currents and
voltages in a circuit
 Capacitance causes the current to lead the applied voltage, whereas inductance
causes the current to lag the applied voltage.

43. Reactive Components
Capacitors
 A capacitor used in an ac circuit continually charges and discharges.
 A capacitor tends to oppose voltage changes across it.
 The reactance of a capacitor is inversely proportional to the value of capacitance C
and operating frequency f.

44. Capacitors Cont’
 The wire leads of a capacitor have resistance and inductance, and the dielectric has
leakage that appears as a resistance value in parallel with the capacitor.

45. Inductors
 An inductor, also called a coil or choke, is simply a winding of multiple turns of
wire.
 When current is passed through a coil, a magnetic field is produced around the
coil.
 If the applied voltage and current are varying, the magnetic field alternately
expands and collapses.
 This causes a voltage to be self-induced into the coil winding, which has the effect
of opposing current changes in the coil.
 This effect is known as inductance.
 When an inductor is used in an ac circuit, this opposition becomes continuous and
constant and is known as inductive reactance

47. Inductors Cont’
 Another important characteristic of an inductor is its quality factor Q, the ratio of
inductive power to resistive power:

48. Resistors
 At low frequencies, a standard low-wattage color-coded resistor offers nearly pure
resistance, but at high frequencies its leads have considerable inductance, and
stray capacitance between the leads causes the resistor to act as a complex RLC
circuit
 To minimize the inductive and capacitive effects, the leads are kept very short in
radio applications.
 The tiny resistor chips used in surface-mount construction of the electronic circuits
preferred for radio equipment have practically no leads except for the metallic end
pieces soldered to the printed-circuit board.

49. Tuned Circuits and Resonance

50.  When XL equals XC, they cancel each other, leaving only the resistance of the
circuit to oppose the current.

51. Tuned Circuits and Resonance Cont’
 The basic definition of resonance in a series tuned circuit is the point at which XL
equals XC.
 With this condition, only the resistance of the circuit impedes the current.
 The total circuit impedance at resonance is Z = R.
 For this reason, resonance in a series tuned circuit can also be defined as the point
at which the circuit impedance is lowest and the circuit current is highest.
 Since the circuit is resistive at resonance, the current is in phase with the applied
voltage.
 Above the resonant frequency, the inductive reactance is higher than the capacitive
reactance, and the inductor voltage drop is greater than the capacitor voltage drop.
 The circuit is inductive, and the current will lag the applied voltage.

52.  At very low frequencies, the capacitive reactance is much greater than the inductive
reactance; therefore, the current in the circuit is very low because of the high
impedance.
 Because the circuit is predominantly capacitive, the current leads the voltage by
nearly 90°.
 As the frequency increases, XC goes down and XL goes up. The amount of leading
phase shift decreases.

53.  The narrow frequency range over which
the current is highest is called the
bandwidth.
 The upper and lower boundaries of the
bandwidth are dei ned by two cutoff
frequencies designated f1 and f2.
 These cutoff frequencies occur where the
current amplitude is 70.7 percent of the
peak current
 Current levels at which the response is
down 70.7 percent are called the half-
power points because the power at the
cutoff frequencies is one-half the power
peak of the curve.

54.  The bandwidth of a resonant circuit is determined by the Q of the circuit.
 Since the bandwidth is approximately centered on the resonant frequency, f1 is the
same distance from fr as f2 is from fr .
 For a linear frequency scale, you can calculate the center or resonant frequency by using
an average of the cutoff frequencies.
 If the Q of a circuit resonant at 18 MHz is 50, then the bandwidth is BW = 18/50 = 0.36
MHz = 360 kHz.

55.  If the circuit Q is very high (>100), then the response curve is approximately
symmetric around the resonant frequency. The cutoff frequencies will then be
roughly equidistant from the resonant frequency by the amount of BW/2.

56.  The bandwidth of a circuit is inversely proportional to Q. The higher Q is, the
smaller the bandwidth. Low Qs produce wide bandwidths or less selectivity. In turn,
Q is a function of the circuit resistance.

58. Parallel Resonant Circuits
 Parallel resonant circuit currents. (a) Parallel resonant circuit. (b) Current
relationships in parallel resonant circuit.

60.  If the Q of the parallel resonant circuit is greater than 10, the following simplified
formula can be used to calculate the resistive impedance at resonance:

61.  Note that the Q of a parallel circuit, which was previously expressed as Q = XL /RW,
can also be computed with the expression :
 where RP is the equivalent parallel resistance, Req in parallel with any other parallel
resistance, and XL is the inductive reactance of the equivalent inductance Leq.
 You can set the bandwidth of a parallel tuned circuit by controlling Q.
 The Q can be determined by connecting an external resistor across the circuit.
 This has the effect of lowering RP and increasing the bandwidth.

62. Filters
 A filter is a frequency-selective circuit.
 Simple filters created by using resistors and capacitors or inductors and capacitors
are called passive filters because they use passive components that do not amplify.
 Some special types of filters are active filters that use RC networks with feedback in
op amp circuits, switched capacitor filters, crystal and ceramic filters, surface
acoustic wave (SAW) filters, and digital filters implemented with digital signal
processing (DSP) techniques.
 Low-pass i lter. Passes frequencies below a critical frequency called the cutoff
frequency and greatly attenuates those above the cutoff frequency.
 High-pass i lter. Passes frequencies above the cutoff but rejects those below it.
 Bandpass i lter. Passes frequencies over a narrow range between lower and upper
cutoff frequencies.
 Band-reject i lter. Rejects or stops frequencies over a narrow range but allows
frequencies above and below to pass.
 All-pass i lter. Passes all frequencies equally well over its design range but has a
fixed or predictable phase shift characteristic.

63. Low-Pass Filter

64. Low-Pass Filter Cont’

65. High-Pass Filter

67. RC Notch Filter
 Notch filters are also referred to as bandstop or band-reject filters

68. LC Filters
 Inductors for lower frequencies are large, bulky, and expensive, but those used at
higher frequencies are very small, light, and inexpensive.
 RC filters are used primarily at the lower frequencies.

69. Filter Terminology
 Passband. This is the frequency range over which the filter passes signals. It is the
frequency range between the cutoff frequencies or between the cutoff frequency and
zero (for low-pass) or between the cutoff frequency and infinity (for high-pass).
 Stop band. This is the range of frequencies outside the passband, i.e., the range of
frequencies that is greatly attenuated by the filter. Frequencies in this range are rejected.
 Attenuation. This is the amount by which undesired frequencies in the stop band are
reduced. It can be expressed as a power ratio or voltage ratio of the output to the input.
Attenuation is usually given in decibels.
 Insertion loss. Insertion loss is the loss the filter introduces to the signals in the
passband. Passive filters introduce attenuation because of the resistive losses in the
components. Insertion loss is typically given in decibels.
 Impedance. Impedance is the resistive value of the load and source terminations of the
filter. Filters are usually designed for specific driving source and load impedances that
must be present for proper operation.
 Ripple. Amplitude variation with frequency in the passband, or the repetitive rise and
fall of the signal level in the passband of some types of filters, is known as ripple. It is
usually stated in decibels. There may also be ripple in the stop bandwidth in some types
of filters.

70.  Shape factor. Shape factor, also known as bandwidth ratio, is the ratio of the stop
bandwidth to the pass bandwidth of a bandpass filter.

71.  Pole. A pole is a frequency at which there is a high impedance in the circuit. It is
also used to describe one RC section of a filter. A simple low-pass RC filter has one
pole.
 Zero. This term refers to a frequency at which there is zero impedance in the circuit.
 Roll-off. Also called the attenuation rate, roll-off is the rate of change of amplitude
with frequency in a filter. The faster the roll-off, or the higher the attenuation rate,
the more selective the filter is, i.e., the better able it is to differentiate between two
closely spaced signals, one desired and the other not.

74. Types of Filters
 The Butterworth filter effect has maximum flatness in response in the pass band
and a uniform attenuation with frequency.
 Chebyshev (or Tchebyschev) filters have extremely good selectivity; i.e., their
attenuation rate or roll-off is high, much higher than that of the Butterworth filter.
 Cauer filters produce an even greater attenuation or roll-off rate than do
Chebyshev filters and greater attenuation out of the passband.
 Also called Thomson filters, Bessel circuits provide the desired frequency response
(i.e., low-pass, bandpass, etc.) but have a constant time delay in the passband.

79. Active Filters
 Active filters are frequency-selective circuits that incorporate RC networks and
amplifiers with feedback to produce low-pass, high-pass, bandpass, and bandstop
performance.

81. Crystal Filters
 Crystal filters are made from the same type of quartz crystals normally used in
crystal oscillators.
 When a voltage is applied across a crystal, it vibrates at a specific resonant
frequency, which is a function of the size, thickness, and direction of cut of the
crystal.