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Modul – 9 Antena dan Propagasi Gelombang Radio (2) TE-09-1313 2 sks Tim Bidang Studi Telekomunikasi Multimedia (Achmad Ansori, Devy Kuswidiastuti, Gatot.

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Presentation on theme: "Modul – 9 Antena dan Propagasi Gelombang Radio (2) TE-09-1313 2 sks Tim Bidang Studi Telekomunikasi Multimedia (Achmad Ansori, Devy Kuswidiastuti, Gatot."— Presentation transcript:

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

2 Propagasi Gelombang Radio Anetenna & Radio-Wave Propogation2

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

4 Band Frekuensi Radio (ITU) ELF SLF ULF VLF LF MF HF VHF UHF SHF EHF Anetenna & Radio-Wave Propogation 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

5 Band Frekuensi Radio (IEEE) (Alternatif) P Band GHz L-Band1 - 2 GHz S-Band GHz C-Band 4-8 GHz X-Band GHz Ku-Band GHz K Band GHz Ka Band GHz U Band40-60 GHz Anetenna & Radio-Wave Propogation5

6 6 Sistem Komunikasi Radio yang sederhana

7 Anetenna & Radio-Wave Propogation7 Atmosfir dari Bumi

8 Anetenna & Radio-Wave Propogation8

9 Troposphere : The lower part of the Earths atmosphere extending Upwards from the Earths 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 Earths poles and 17 km at the equator. Stratosphere : 20 – 50 km 9Anetenna & Radio-Wave Propogation

10 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 Earths ionosphere extends approximately from a height of 50 km to a height of km. 10Anetenna & Radio-Wave Propogation

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12 Mekanisme perambatan Anetenna & Radio-Wave Propogation12

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14 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). 14Anetenna & Radio-Wave Propogation

15 15 Propagasi Gelombang Tanah (Ground Wave/Surface wave)

16 Anetenna & Radio-Wave Propogation16 Mengikuti contour bumi Dapat merambat pada jarak tertentu Frekuensi sampai 2 MHz Contoh : Gelombang Radio AM, Komunikasi untuk navigasi, Propagasi Gelombang Tanah (Ground Wave / Surface Wave)

17 Anetenna & Radio-Wave Propogation17 Space wave propagation

18 Anetenna & Radio-Wave Propogation18 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.

19 Anetenna & Radio-Wave Propogation19 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 Ɛ 0 or magnetic constant μ 0 and the speed of light in a vacuum c; its value is approximately ohms

20 Anetenna & Radio-Wave Propogation20 There are numerous other synonyms, including: intrinsic impedance of vacuum, intrinsic impedance of free space, the vacuum impedance,

21 Anetenna & Radio-Wave Propogation21 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.

22 Anetenna & Radio-Wave Propogation22

23 Anetenna & Radio-Wave Propogation23 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

24 Anetenna & Radio-Wave Propogation24 Propagasi Line-of-Sight (diatas 30 MHz)

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 Propogation25

26 Anetenna & Radio-Wave Propogation26 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

27 Anetenna & Radio-Wave Propogation27 Rugi Free Space Rugi Ruang bebas, antena isotropik ideal P t = daya sinyal antena pemancar P r = daya sinyal antena penerima = panjang gelombang carrier d = jarak propagasi antar antena c = Kecepatan cahaya ( m/s) Dimana d dan sama satuannya (misal: meter)

28 Anetenna & Radio-Wave Propogation28 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

29 Anetenna & Radio-Wave Propogation29

30 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 Propogation30 Propagasi Gelombang Angkasa (Sky Wave)

31 Anetenna & Radio-Wave Propogation31 Ionospheric wave : A radio wave returned to the Earth by ionospheric reflection.

32 Anetenna & Radio-Wave Propogation32 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 Propagasi Gelombang Angkasa (Sky Wave, 2 – 30 MHz)

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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 Propogation37

38 Anetenna & Radio-Wave Propogation38 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

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41 Anetenna & Radio-Wave Propogation41 Ringkasan Mode Propagasi

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