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Antena: 

uku@stttelkom.ac.id Antena By Uke Kurniawan Usman Laboratoria SISKOM – STT Telkom uku@sttttelkom.ac.id

Antenna - How it Works: 

uku@stttelkom.ac.id Antenna - How it Works The antenna converts radio frequency electrical energy fed to it (via the transmission line) to an electromagnetic wave propagated into space. The physical size of the radiating element is proportional to the wavelength. The higher the frequency, the smaller the antenna size. Assuming that the operating frequency in both cases is the same, the antenna will perform identically in Transmit or Receive mode

Slide 3: 

uku@stttelkom.ac.id The type of system you are installing will help determine the type of antenna used. Generally speaking, there are two ‘types’ of antennae: Directional - this type of antenna has a narrow beamwidth; with the power being more directional, greater distances are usually achieved but area coverage is sacrificed - Yagi, Panel, Sector and Parabolic antennae - an EUM, NCL Station/Master will use this type of antenna in both Point to Point and Point to Multipoint 2. Omni-Directional - this type of antenna has a wide beamwidth and radiates 3600; with the power being more spread out, shorter distances are achieved but greater coverage attained - Omni antenna

Macam – maca konfigurasi antena : 

uku@stttelkom.ac.id Macam – maca konfigurasi antena Dipole Dipole dengan pemantul Yagi Dipole dengan pemantul dan penyearah Horn Hpbw Parabola dengan prime focus Parabola dengan casegrain

Yagi: 

uku@stttelkom.ac.id Yagi better suited for shorter links lower dBi gain; usually between 7 and 15 dBi

Parabolic: 

uku@stttelkom.ac.id Parabolic used in medium to long links gains of 18 to 28 dBi most common

Sectoral: 

uku@stttelkom.ac.id Sectoral directional in nature, but can be adjusted anywhere from 45 0 to 180 0 typical gains vary from 10 to 19 dBi

Omni: 

uku@stttelkom.ac.id Omni used at the CCU or Master NCL for wide coverage typical gains of 3 to 10 dBi

Polarization: 

uku@stttelkom.ac.id An antennas polarization is relative to the E-field of antenna. If the E-field is horizontal, than the antenna is Horizontally Polarized. If the E-field is vertical, than the antenna is Vertically Polarized. Polarization No matter what polarity you choose, all antennas in the same RF network must be polarized identically regardless of the antenna type.

Slide 10: 

uku@stttelkom.ac.id Polarization Vertical Horizontal Vertical Polarization: The electric field is vertical to the ground (In the maximum gain direction) Horizontal Polarization: The electric field is parallel to the ground (In the maximum gain direction)

Slide 11: 

uku@stttelkom.ac.id + 45 degree slant - 45 degree slant Polarization

Slide 12: 

uku@stttelkom.ac.id V/H (Vertical/Horizontal) Slant (+/- 45°) Polarization

Slide 13: 

uku@stttelkom.ac.id Polarization may deliberately be used to: Increase isolation from unwanted signal sources (Cross Polarization Discrimination (x-pol) typically 25 dB) Reduce interference Help define a specific coverage area Horizontal Vertical

Slide 14: 

uku@stttelkom.ac.id Radiation Pattern  A graphical representation of the intensity of the radiation vs. the angle from the perpendicular.  The graph is usually circular, the intensity indicated by the distance from the centre based in the corresponding angle. Antenna Radiation Pattern

Radiation Patern: 

uku@stttelkom.ac.id Radiation Patern Omnidirectional Radiation Pattern boresight main lobe side lobe (elevation)

Slide 16: 

uku@stttelkom.ac.id Upper Side Lobe Suppression (dB) Side lobes

Contoh Radiation Patern: 

uku@stttelkom.ac.id Log periodic dipole array (LPDA) Contoh Radiation Patern Dipoles Transmission line - BW is smaller than LPDA typical gain 12 – 14 dB Reflector Driven element (dipole) Directors Yagi antenna Directional Radiation Pattern main lobe main lobe side lobe back lobe - very wide BW, with constant SWR typical gain 10 dBi

Slide 18: 

uku@stttelkom.ac.id Antenna Radiation pattern Directional Antenna Radiation Pattern Horizontal plane Vertical plane

Slide 19: 

uku@stttelkom.ac.id Antenna Radiation pattern Horizontal plane Vertical plane Omni-directional Antenna Radiation Pattern

Slide 20: 

uku@stttelkom.ac.id Typical Radiation Pattern for a Yagi

Slide 21: 

uku@stttelkom.ac.id Typical Radiation Pattern for a Sector

Slide 22: 

uku@stttelkom.ac.id Pattern

Slide 23: 

uku@stttelkom.ac.id Gain Unless otherwise specified, the gain usually refers to the direction of maximum radiation.

Slide 24: 

uku@stttelkom.ac.id Antenna gain is usually expressed in dBi or dBd dBi Gain relative to an isotropic antenna when the reference antenna is an isotropic antenna. dBd Gain relative to a half-wave dipole when the reference antenna is a half-wave dipole. Gain Unit

Slide 25: 

uku@stttelkom.ac.id half-wave dipole isotropic radiator eg: 0dBd = 2.15dBi 2.15 dB dBd and dBi

Slide 26: 

uku@stttelkom.ac.id Wavelength 1/2 Wavelength 1/4 Wavelength 1/4 Wavelength 1/2 Wavelength Dipole 1900MHz ：78.95 mm 800MHz ：187.5mm Dipoles

Slide 27: 

uku@stttelkom.ac.id One dipole Received Power： 1mW multiple dipoles Received Power ： 4 mW GAIN = 10log(4mW/1mW) = 6dBd Dipoles

Slide 28: 

uku@stttelkom.ac.id 10log(8mW/1mW) = 9dBd Sector antenna Received Power ： 8mW Omnidirectional array Received Power ： 4mW ( down look) Antenna Dipoles

Slide 29: 

uku@stttelkom.ac.id 9.5 W 80 ohms 50 ohms forward: 10W reverse: 0.5W Return Loss：10log(10/0.5) = 13dB VSWR (Voltage Standing Wave Ratio) VSWR Usual Request ： VSWR1.5 Reflection Coefficient ： =(VSWR-1)/(VSWR+1) Return Loss ： RL=-20lg 

Slide 30: 

uku@stttelkom.ac.id 120° ( eg) Peak Peak - 10dB Peak - 10dB 10 dB Beamwidth 60° ( eg) Peak Peak - 3dB Peak - 3dB 3 dB Beamwidth Beamwidth