ANTENNA I
CHAPTER 4: LINEAR WIRE
ANTENNAS
LECTURE 14
Fall 2015
Instructor: Dr. Neshat
[Refer to notes]
2
Power
density, radiation intensity and radiation
resistance
Directivity
Input resistance
Copyright 2015 by Mohammad Neshat. University of Tehran. All rights reserved.
Normalized radiation power l<
3
-3dB
Copyright 2015 by Mohammad Neshat. University of Tehran. All rights reserved.
Normalized radiation power l>
4
Copyright 2015 by Mohammad Neshat. University of Tehran. All rights reserved.
Current distribution
5
Copyright 2015 by Mohammad Neshat. University of Tehran. All rights reserved.
Radiation & input resistance
6
Copyright 2015 by Mohammad Neshat. University of Tehran. All rights reserved.
Half-wavelength dipole (l=/2)
7
Radiated fields:
Power density:
Power intensity:
Copyright 2015 by Mohammad Neshat. University of Tehran. All rights reserved.
Half-wavelength dipole (l=/2) (cont.)
8
Radiated fields:
Directivity:
Effective area:
Copyright 2015 by Mohammad Neshat. University of Tehran. All rights reserved.
Half-wavelength dipole (l=/2) (cont.)
9
Radiation resistance:
Input impedance:
Copyright 2015 by Mohammad Neshat. University of Tehran. All rights reserved.
Linear elements near or on the ground or conductor
10
Copyright 2015 by Mohammad Neshat. University of Tehran. All rights reserved.
Image theory for vertical dipole
11
Copyright 2015 by Mohammad Neshat. University of Tehran. All rights reserved.
Image theory for vertical dipole (cont.)
12
Copyright 2015 by Mohammad Neshat. University of Tehran. All rights reserved.
Image theory (cont.)
13
Copyright 2015 by Mohammad Neshat. University of Tehran. All rights reserved.
Field of a vertical dipole above PEC
14
[Field of dipole at origin] x [Array factor]
Copyright 2015 by Mohammad Neshat. University of Tehran. All rights reserved.
Radiation pattern of vertical dipole
15
Copyright 2015 by Mohammad Neshat. University of Tehran. All rights reserved.
Radiation pattern of vertical dipole (cont.)
16
Copyright 2015 by Mohammad Neshat. University of Tehran. All rights reserved.
Antenna parameters for vertical dipole
17
Copyright 2015 by Mohammad Neshat. University of Tehran. All rights reserved.
Antenna parameters for vertical dipole (cont.)
18
Copyright 2015 by Mohammad Neshat. University of Tehran. All rights reserved.
Image theory for horizontal dipole
19
Copyright 2015 by Mohammad Neshat. University of Tehran. All rights reserved.
Field of a horizontal dipole above PEC
20
[Field of dipole at origin] x [Array factor]
Copyright 2015 by Mohammad Neshat. University of Tehran. All rights reserved.
Radiation pattern of horizontal dipole
21
Copyright 2015 by Mohammad Neshat. University of Tehran. All rights reserved.
Radiation pattern of horizontal dipole (cont.)
22
Copyright 2015 by Mohammad Neshat. University of Tehran. All rights reserved.
Antenna parameters for horizontal dipole
23
Copyright 2015 by Mohammad Neshat. University of Tehran. All rights reserved.
Antenna parameters for horizontal dipole (cont.)
24
For h = 0 the element is shorted and it does not radiate.
Copyright 2015 by Mohammad Neshat. University of Tehran. All rights reserved.
Monopole
25
Copyright 2015 by Mohammad Neshat. University of Tehran. All rights reserved.
