Paper presentation Ultra-Portable Devices Paper: Jaechun Lee and - - PowerPoint PPT Presentation

Paper presentation – Ultra-Portable Devices

Paper: Presented by:

Jaechun Lee and Sangwook Nam, Effective Area of a Receiving Antenna in a Lossy Medium. IEEE Transactions on Antennas and Propagation,Vol. 57, No.6, June 2009

Rohit Chandra

2010-05-09 1 Paper Presentation - Ultra Portable Devices

Outline

• Introduction
• Radiation Property of Hertzian dipole in Lossy medium
• Effective Area
• Simulation
• Results
• Summary

2010-05-09 2 Paper Presentation - Ultra Portable Devices

Introduction

• Antennas in Lossy Medium:
• Geophysical Survey
• Submarine Communication
• Implants in human body

2010-05-09 Paper Presentation - Ultra Portable Devices 3

dt t e j z H

t t z



        



1 2 1

1 ) ( ˆ 

Hankel Function

• f 2nd kind

e

A

Introduction

2010-05-09 4 Paper Presentation - Ultra Portable Devices

2

4        R G G P P

RX TX TX RX

 

Friis Formula in free space            4

2 RX e

G A

• derived using gain and

impedance of small dipoles in free space in Friis Formula

• In lossy medium gain and

impedance cannot be obtained simply as in free space

• Small dipole  Hertzian dipole,

infinite power is consumed in vicinity in lossy medium

• Insulated Hertzian Dipole

Radiation Property of an Insulated Hertzian Dipole in a lossy medium

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Lossless Sphere

 

2 * 1 ' 1

| | ) ( ˆ ) ( ˆ Re 3 4 TX ka H ka H j P

in

  

Input Power derived by integration of complex Poynting Vector over the surface at r = a T is derived by continuity of Electric and Magnetic field at r = a in r r r

P r e G r e TX P

2 2 2 2 2 2 '

4 | | ] Re[ sin 2 1   

   

 

Radiated Power density in far field r∞ and α is attenuation constant

 

 

eff

D ka H ka H j G      

* 1 ' 1 2

) ( ˆ ) ( ˆ Re Re sin 2 3

Lossy Medium

Radiation Property[contd..]

2010-05-09 Paper Presentation - Ultra Portable Devices

in r eff r

P r e D P

2 2 '

4 

 



6

Two factors of loss in lossy medium

• 1. Attenuation

loss in propagation

• 2. Disspiation Loss in

the reactive energy stored in the near field

Effective Area

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in in RX

R l E P 8

2



  

   4 Re 3 2 2

2 2 2 eff in in

l k T I P R  

sin TE k k E

i in

  

   

2 2 2 2 2

Re 2 1 Re sin 2 3               E k

eff i

           4

2 eff e

G A ' plane

P

 

*

Re 2     

eff

Friis Formula for Lossy Medium

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2

4         

 R eff RX TX TX RX

e R G G P P



 

Simulation

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Summary

• Effective area has been derived for estimation of power

transmission in Lossy medium

• When medium is both electric as well as magnetic lossy the

extended Friis formula for the lossy medium can be used.

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