Foundation Licence Feeders and Antennas. What they do Feeder: transfers RF current between a...
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Transcript of Foundation Licence Feeders and Antennas. What they do Feeder: transfers RF current between a...
![Page 1: Foundation Licence Feeders and Antennas. What they do Feeder: transfers RF current between a transceiver and antenna without radiating radio waves. (Hope.](https://reader030.fdocuments.net/reader030/viewer/2022032722/56649ceb5503460f949b6fe0/html5/thumbnails/1.jpg)
Foundation Licence
Feeders and Antennas
![Page 2: Foundation Licence Feeders and Antennas. What they do Feeder: transfers RF current between a transceiver and antenna without radiating radio waves. (Hope.](https://reader030.fdocuments.net/reader030/viewer/2022032722/56649ceb5503460f949b6fe0/html5/thumbnails/2.jpg)
What they do
Feeder: transfers RF current between a transceiver and antenna without radiating radio waves. (Hope springs eternal).
Antenna: transfers RF energy with best possible efficiency from RF current to RF wave or from RF wave to RF current.
![Page 3: Foundation Licence Feeders and Antennas. What they do Feeder: transfers RF current between a transceiver and antenna without radiating radio waves. (Hope.](https://reader030.fdocuments.net/reader030/viewer/2022032722/56649ceb5503460f949b6fe0/html5/thumbnails/3.jpg)
Types of Feeder
Coaxial Cable (coax)
Ribbon Feeder
Open Wire Feeder
![Page 4: Foundation Licence Feeders and Antennas. What they do Feeder: transfers RF current between a transceiver and antenna without radiating radio waves. (Hope.](https://reader030.fdocuments.net/reader030/viewer/2022032722/56649ceb5503460f949b6fe0/html5/thumbnails/4.jpg)
Types of Plug
BNC Plug
PL 259 Plug
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Types of Antenna
![Page 6: Foundation Licence Feeders and Antennas. What they do Feeder: transfers RF current between a transceiver and antenna without radiating radio waves. (Hope.](https://reader030.fdocuments.net/reader030/viewer/2022032722/56649ceb5503460f949b6fe0/html5/thumbnails/6.jpg)
At Foundation Level:
Half Wave Dipole ¼ Wave ground plane 5/8 ground plane Yagi antenna End fed wire.
![Page 7: Foundation Licence Feeders and Antennas. What they do Feeder: transfers RF current between a transceiver and antenna without radiating radio waves. (Hope.](https://reader030.fdocuments.net/reader030/viewer/2022032722/56649ceb5503460f949b6fe0/html5/thumbnails/7.jpg)
The Half – Wave Dipole
hal
f w
avel
en
gth
Transceiver
dip
ole
![Page 8: Foundation Licence Feeders and Antennas. What they do Feeder: transfers RF current between a transceiver and antenna without radiating radio waves. (Hope.](https://reader030.fdocuments.net/reader030/viewer/2022032722/56649ceb5503460f949b6fe0/html5/thumbnails/8.jpg)
¼ Antenna
Coax Feed
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5/8 Antenna
• Improved low angle radiation pattern
• Has ‘gain’ (4dB)
• Coil: for matching to transmitter (adds 1/8 )
![Page 10: Foundation Licence Feeders and Antennas. What they do Feeder: transfers RF current between a transceiver and antenna without radiating radio waves. (Hope.](https://reader030.fdocuments.net/reader030/viewer/2022032722/56649ceb5503460f949b6fe0/html5/thumbnails/10.jpg)
The Yagi Antenna
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Ways of indicating “Gain”
3dB
6dB
9dB
10dB
2 times
4 times
8 times
10 times
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Effective Radiated Power (erp)
erp = antenna gain × transmit power
![Page 13: Foundation Licence Feeders and Antennas. What they do Feeder: transfers RF current between a transceiver and antenna without radiating radio waves. (Hope.](https://reader030.fdocuments.net/reader030/viewer/2022032722/56649ceb5503460f949b6fe0/html5/thumbnails/13.jpg)
Polarisation
Direction of Polarisation is the same as the direction of electric field.
Vertical Polarisation
Horizontal Polarisation
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Matching Antennas / Feeders
Source of Energy Load
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Matching Antennas
Source of Energy Load
Energy reflected back to source
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SWR: Standing Wave Ratio
How good a match?
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You don’t have to know this yet!
But…
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Antenna Tuning Unit (ATU)
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SWR Meter
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Variation of SWR with Dipole Length
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Dummy Loads
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It’s all a matter of balance
Balance = electrical symmetry
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The Balun
Retains the electrical symmetry of a balanced antenna if we connect it to an unbalanced feeder.
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Dipole Antenna
(Balanced)
Coaxial cable feeder
(unbalanced)
Balun