Presentation is loading. Please wait.

Presentation is loading. Please wait.

1 EMLAB Chapter 9. Broadband dipoles and matching techniques.

Similar presentations


Presentation on theme: "1 EMLAB Chapter 9. Broadband dipoles and matching techniques."— Presentation transcript:

1 1 EMLAB Chapter 9. Broadband dipoles and matching techniques

2 2 EMLAB Contents 1.Introduction 2.Biconical antenna 3.Triangular sheet, Bow-tie, and wire simulation 4.Cylindrical dipole 5.Folded dipole 6.Discone and conical skirt monopole 7.Sleeve dipole 8.Matching techniques

3 3 EMLAB Fundamental limit of BW The bandwidth of an antenna (which can be enclosed in a sphere of radius r) can be improved only if the antenna utilizes efficiently, with its geometrical configuration, the available volume within the sphere

4 4 EMLAB

5 5 9.2 Bi-conical antenna Dominant TEM mode

6 6 EMLAB Electric and magnetic fields, and associated voltages and currents, for a bi-conical antenna.

7 7 EMLAB

8 8 The input impedance is independent of frequency.

9 9 EMLAB

10 10 EMLAB

11 11 EMLAB 9.3 Triangular sheet, bow-tie, wire simulation Triangular sheet Bow-tie Wire-simulation

12 12 EMLAB

13 13 EMLAB 9.4 Cylindrical dipole Thick dipole has broad band characteristics.

14 14 EMLAB

15 15 EMLAB Equivalent radii

16 16 EMLAB Dielectric coating 1.Increasing Re{P} or Re{Q} a.Increases the peak input admittance b.Increase the electrical length (lowers the resonant frequency) c.Narrows the bandwidth 2. Increasing Im{P} or Im{Q} a.decreases the peak input admittance b.decrease the electrical length (lowers the resonant frequency) c.increase the bandwidth d.Accentuate the power dissipated (decreases the radiation efficiency) e.Accentuate the traveling wave component of the current distribution

17 17 EMLAB 9.5 Folded dipole 1.FM broadcasting receiving (88~ 108MHz). 2.TV antenna (54~ 216MHz)

18 18 EMLAB

19 19 EMLAB

20 20 EMLAB

21 21 EMLAB

22 22 EMLAB Equivalent circuit of folded dipole

23 23 EMLAB

24 24 EMLAB

25 25 EMLAB 9.6 Discone and conical skirt monopole

26 26 EMLAB 9.7 Matching techniques

27 27 EMLAB

28 28 EMLAB

29 29 EMLAB

30 30 EMLAB Balun and transformers

31 31 EMLAB

32 32 EMLAB


Download ppt "1 EMLAB Chapter 9. Broadband dipoles and matching techniques."

Similar presentations


Ads by Google