Feeders

• Max power transfer from transmitter to aerial system occurs when transmiter output impedance and antenna system input impedance are equal
• Half wave dipole antenna in free space has theoretical impedance of about 72Ω at its centre;  lower near ground
• Coaxial cable can be used to feed power to this system as the antenna presents a reasonable match to the feeder keeping losses low;  the coax presents a good match to the transmitter

Course Guide Topics

1. Purpose
2. Types of feeder
3. Characteristic Impedance
4. Parallel Conductor Line
5. Preventing Line Radiation
6. Balanced Line
7. Coaxial Line (Coax) (1)
8. Coaxial Line (Coax) (2)
9. Waveguide
10. Velocity Factor
11. Velocity Factor (Contd)
12. Terminated Line
    (Matched Case) (1)
13. Terminated Line
    (Matched Case) (2)
14. Terminated Line
    (Unmatched Case)
15. Standing Waves (1)
16. Standing Waves (2)
17. Standing Waves (3)
18. Line Loss (1)
19. Line Loss (2)
20. Matching
21. Matching – Quarter Wave Transformer (1)
22. Matching – Quarter Wave Transformer (2)
23. Lines as Tuned Circuits
24. Open Circuit
25. Short Circuit
26. Stubs
27. Stub Characteristics
28. Antenna Tuning Units – ATU
29. Balance/Unbalance
30. Baluns
31. Typical Baluns
32. 1:1 Current Balun
33. 4:1 Voltage Balun
34. 1:1 Voltage Balun
35. 4:1 Transmission Line Voltage Balun