1. Modul – 9 Antena dan Propagasi Gelombang Radio (2)
2 sks
Tim Bidang Studi
Telekomunikasi Multimedia
(Achmad Ansori, Devy Kuswidiastuti, Gatot Kusrahardjo, M Aries Purnomo)
Anetenna & Radio-Wave Propogation

2. Propagasi Gelombang Radio
Anetenna & Radio-Wave Propogation

3. Anetenna & Radio-Wave Propogation
radio waves, hertzian waves :
An electromagnetic wave propagated in space without artificial
guide and having by convention a frequency lower than 3 000
GHz.
Note :
The electromagnetic waves having frequencies around 3 000
GHz may be regarded either as radio waves or optical waves.
Propagasi adalah perambatan gelombang melalui suatu media
( udara, air, ruang hampa )
Anetenna & Radio-Wave Propogation

4. Band Frekuensi Radio (ITU)
ELF
SLF
ULF
VLF LF MF HF
VHF
UHF
SHF
EHF
3-30 Hz Extremely Low Frequency
Hz Super Low Frequency
300 Hz-3 kHz Ultra Low Frequency
3-30 kHz Very Low Frequency
kHz Low Frequency
300 kHz-3 MHz Medium Frequency
3-30 MHz High Frequency
MHz Very High Frequency
300 MHz-3 GHz Ultra High Frequency
3-30 GHz Super High Frequency
GHz Extremely High Frequency
Anetenna & Radio-Wave Propogation

5. Band Frekuensi Radio (IEEE) (Alternatif)
P Band GHz
L-Band GHz
S-Band GHz
C-Band GHz
X-Band GHz
Ku-Band GHz
K Band GHz
Ka Band GHz
U Band GHz
Anetenna & Radio-Wave Propogation

6. Anetenna & Radio-Wave Propogation
Sistem Komunikasi Radio yang sederhana
Anetenna & Radio-Wave Propogation

7. Anetenna & Radio-Wave Propogation
Atmosfir dari Bumi
Anetenna & Radio-Wave Propogation

8. Anetenna & Radio-Wave Propogation

9. Anetenna & Radio-Wave Propogation
Troposphere :
The lower part of the Earth’s atmosphere extending
Upwards from the Earth’s surface, in which temperature
decreases with height except in local layers of
temperature inversion.
This part of the atmosphere extends to an altitude of
about 9 km at the Earth’s poles and 17 km at the
equator.
Stratosphere : 20 – 50 km
Anetenna & Radio-Wave Propogation

10. Anetenna & Radio-Wave Propogation
Ionosphere :
That part of the upper atmosphere characterized by the
presence of ions and free electrons mainly arising from
photo-ionization, the electron density being sufficient to
produce significant modification of the propagation of radio
waves in certain frequency bands.
Note :
The Earth’s ionosphere extends approximately from a height
of 50 km to a height of 2 000 km.
Anetenna & Radio-Wave Propogation

11. Anetenna & Radio-Wave Propogation

12. Anetenna & Radio-Wave Propogation
Mekanisme perambatan
Anetenna & Radio-Wave Propogation

13. Anetenna & Radio-Wave Propogation

14. Anetenna & Radio-Wave Propogation
Ground wave :
A radio wave basically determined by the properties of the
ground which propagates in the troposphere and which is mainly
due to diffraction around the Earth.
A ground wave is composed of two separate component waves-
the surface wave and the space wave
The surface wave travels along the surface of the ground.
A surface wave flows the curvature of the Earth due to the
process of diffraction.
The space wave follows two distinct paths from transmitting
antenna to receiving antenna--one through the air directly to the
receiving antenna (direct wave or path), and the other reflected
from the ground to the receiving antenna (ground-reflected wave
or path).
Anetenna & Radio-Wave Propogation

15. Propagasi Gelombang Tanah (Ground Wave/Surface wave)
Anetenna & Radio-Wave Propogation

16. Propagasi Gelombang Tanah (Ground Wave / Surface Wave)
Mengikuti contour bumi
Dapat merambat pada jarak tertentu
Frekuensi sampai 2 MHz
Contoh :
Gelombang Radio AM, Komunikasi untuk navigasi,
Anetenna & Radio-Wave Propogation

17. Anetenna & Radio-Wave Propogation
Space wave propagation
Anetenna & Radio-Wave Propogation

18. Anetenna & Radio-Wave Propogation
line-of-sight propagation :
Propagation between two points for which the direct ray is
sufficiently clear of obstacles for diffraction to be of negligible
effect.
free-space propagation :
Propagation of an electromagnetic wave in a homogeneous
ideal dielectric medium which may be considered of infinite
extent in all directions.
Note  : 
For propagation in free space, the magnitude of each vector of the
electromagnetic field in any given direction from the source beyond a
suitable distance determined by the size of the source and the wavelength
is proportional to the reciprocal of the distance from the source.
Anetenna & Radio-Wave Propogation

19. Anetenna & Radio-Wave Propogation
Impedance of free space :
The impedance of free space, Z0, is a physical constant relating
the magnitudes of the electric and magnetic fields of
electromagnetic radiation travelling through free space.
That is, Z0 = |E|/|H|, where |E| is the electric field strength and
|H| magnetic field strength.
The impedance of free space equals the product of the vacuum
permeability Ɛ0 or magnetic constant μ0 and the speed of light
in a vacuum c; its value is approximately ohms
Anetenna & Radio-Wave Propogation

20. Anetenna & Radio-Wave Propogation
There are numerous other synonyms, including:
intrinsic impedance of vacuum,
intrinsic impedance of free space,
the vacuum impedance,
Anetenna & Radio-Wave Propogation

21. Anetenna & Radio-Wave Propogation
Fresnel zones :
If unobstructed, radio waves will travel in a straight line from
the transmitter to the receiver.
But if there are obstacles near the path, the radio waves
reflecting off those objects may arrive out of phase with the
signals that travel directly and reduce the power of the received
signal.
On the other hand, the reflection can enhance the power of
the received signal if the reflection and the direct signals arrive
in phase.
Sometimes this results in the counterintuitive finding that
reducing the height of an antenna increases the signal-to-noise
ratio.
Anetenna & Radio-Wave Propogation

22. Anetenna & Radio-Wave Propogation

23. Fn = The nth Fresnel Zone radius in metres
d1 = The distance of P from one end in metres
d2 = The distance of P from the other end in metres
λ = The wavelength of the transmitted signal in metres
Anetenna & Radio-Wave Propogation

24. Propagasi Line-of-Sight (diatas 30 MHz)
Anetenna & Radio-Wave Propogation

25. Propagasi Line-of-Sight
Sinyal pada VHF dan range yang lebih tinggi tidak selamanya dapat dikembalikan ke bumi oleh ionosphere
Kebanyakan komunikasi terrestrial menggunakan frekuensi-frekuensi yang diradiasikan langsung dari pemancar ke penerima
Tipe propagasi ini disebut propagasi gelombang ruang (space-wave), garis pandang (line-of-sight), atau propagasi troposfer
Anetenna & Radio-Wave Propogation

26. Persamaan Line-of-Sight
LOS, secara optik (Penerima harus bisa melihat pemancar) :
LOS efektif, atau radio (Penerima bisa “melihat” sinyal yang dikirim) :
d = jarak antara antenna dan horizon (km)
h = Tinggi antenna (m)
K = faktor kelengkungan bumi, karena sifat refraksi, misal : K = 4/3
Anetenna & Radio-Wave Propogation

27. Anetenna & Radio-Wave Propogation
Rugi Free Space
Rugi Ruang bebas, antena isotropik ideal
Pt = daya sinyal antena pemancar
Pr = daya sinyal antena penerima
 = panjang gelombang carrier
d = jarak propagasi antar antena
c = Kecepatan cahaya ( m/s)
Dimana d dan  sama satuannya (misal: meter)
Anetenna & Radio-Wave Propogation

28. Propagasi Line-of-Sight
Pemancar dan Penerima harus dalam garis pandang (line of sight)
Komunikasi satelite – sinyal diatas 30 MHz tidak dipantulkan oleh ionosfer
Komunikasi di Bumi (Terrestrial) – antena harus berada dalam garis effective karena adanya refraksi
Refraksi – pembelokan gelombang mikro oleh atmosfer
Kecepatan gelombang elektromagnetik merupakan fungsi kerapatan medium
Bila gelombang berubah medium, kecepatan akan berubah.
Gelombang akan dibelokkan pada bidang batas antar medium
Anetenna & Radio-Wave Propogation

29. Anetenna & Radio-Wave Propogation

30. Propagasi Gelombang Angkasa
(Sky Wave)
Komunikasi jarak-jauh pada band frekuensi tinggi, dimungkinkan karena adanya refraksi didaerah atmosfer yang disebut ionosfer
Ionosfer dibagi menjadi tiga daerah yang disebut lapisan D, E, dan F
Ionisasi berbeda untuk ketinggian diatas bumi yang berbeda dan dipengaruhi oleh waktu (siang-malam) dan aktivitas matahari.
Anetenna & Radio-Wave Propogation

31. Anetenna & Radio-Wave Propogation
Ionospheric wave :
A radio wave returned to the Earth by ionospheric reflection.
Anetenna & Radio-Wave Propogation

32. Propagasi Gelombang Angkasa
(Sky Wave, 2 – 30 MHz)
Sinyal dipantulkan dari lapisan ionofer kembali ke bumi
Sinyal dapat menjalar dalam beberapa lintasan, bolak-balik antara ionosfer dan permukaan bumi
Efek pantulan disebabkan oleh refraksi
Contoh :
Radio Amatir
Radio CB
Anetenna & Radio-Wave Propogation

33. Anetenna & Radio-Wave Propogation

34. Anetenna & Radio-Wave Propogation

35. Anetenna & Radio-Wave Propogation

36. Anetenna & Radio-Wave Propogation

37. Mode Propagasi Lainnya
Tropospheric Scatter – memungkinkan peng-gunaan penghamburan (scattering) gelombang radio di lapisan troposfer untuk merambatkan sinyal dalam range frekuensi 250 MHz –5 GHz .
Anetenna & Radio-Wave Propogation

38. Anetenna & Radio-Wave Propogation
Sistem Troposcatter di Indonesia
Surabaya – Banjarmasin Troposcatter System :
Surabaya – G Sandangan ( Madura ) : Line of Sight
G Sandangan – G Gerahan Lalang (Madura) : Line of Sight
G Gerahan Lalang – G Karamaian ( Kalimantan ) :
Troposcatter
G Karamaian – Banjarmasin : Line of Sight
Anetenna & Radio-Wave Propogation

39. Anetenna & Radio-Wave Propogation

40. Anetenna & Radio-Wave Propogation

41. Anetenna & Radio-Wave Propogation
Ringkasan Mode Propagasi
Anetenna & Radio-Wave Propogation

42. Anetenna & Radio-Wave Propogation