Research subject: Determination of Structural Equation for Normal Mode Helical Antenna having

Dielectric or Magnetic Material inside

Presented by : Nguyen Thanh Tuan (First Semester of Master Degree)

Supervisor : Prof. Dr. Yoshihide Yamada

Co-Supervisor : Dr. A.K.M Muzahidul Islam Assoc. Prof. Dr. Sabariah Bt. Baharun

27th March 2015

Outline of this presentation

1. What is Antenna ?

2. What is Normal Mode Helical Antenna (NMHA) ?

3. Structural Determination Method

4. Study Subject

5. Research Schedule

6. Present Situation

7. Conclusion

1. What is Antenna ?

Fig 1.Mobile Communication Fig 2.Satellite Communication

• Applications of Antennas:

• Main roles: Transmit and receive radio wave• Important characteristics: Antenna gain, Radiation pattern,

Impedance matching to radio equipments.

AntennaAntenna

1. What is Antenna ?

Long distance Communication

Short distance Communication

Parabolic Reflectors

Array Antennas

Patch Antennas

Helical Antennas

• Categorization of Antennas:

High Gain Low gain, Small Size

Tag Antenna

Antennas for Radio Frequency Identification (RFID)

Antennas for Tire Pressure Monitoring System (TPMS)

• Application of Small Antenna:

Normal-Mode Helical Antenna (NMHA)

1. What is Antenna ?

Reader Antenna

2. What is NMHA ?

Categorization of Helical Antennas

Axial Mode

Normal Mode Radiation Pattern

• Main radiation is in the antenna axis direction

• Circumference (C) is one wavelength (λ)

• Applications: Satellite ant, Circular polarization ant.

• Main radiation is in the normal direction of the antenna axis

• Height of antenna is less than 1/100 wavelength (λ)

• Applications: RFID tag, TPMS

H

～HA

DA

～

RD - jXDRL + jXL

N

2. What is NMHA ?

• Operational Explaination of NMHA

N

Small Dipole

Small LoopsH << λ

• Electrical Working Condition:Resonant Structure: XC = XL

XC: CapacitanceXL: Inductance

Treatment: Antenna current is divided into 2 parts: the straight part (small dipole) and circular parts (small loops)

3. Structural Determination Method

0.005 0.010 0.015 0.020 0.025 0.0300.005

0.010

0.015

0.020

0.025

0.030

0 2 4 6 8 10

DA/

HA/

N = 5

N = 7

N = 11

f0 = 315 MHzλ = 0.95 md = 0.55 mm

Self-Resonant Structure

• Equation for self-resonant structures (in Free Space ε0 =1)

AA

A

AA

A

HD

DN

DHN

H

209

)(7.19600

)92.0(

279 2

2

XC=XL

• Equation for Input impedance)( CLlrLrDin XXjRRRZ

In self resonant-structure, XL = XC so Zin = Rin = RrD + RrL + Rl

Here, RrD, RrL are the radiation resistance of the small dipole, small loops and Rl is the ohmic resistance of the antenna wire, respectively.

4. Study Subject

Actual NMHA

• Study about resonance structures in dielectric or magnetic (by Electromagnetic simulations)

• Electric field and Magnetic field distributions in dielectric or magnetic

• From resonance curves, we derive resonance equation.

• Determination of Structural Equation for Normal Mode Helical Antenna having Dielectric or Magnetic Material inside (ε1, µ1)

5. Research Schedule

Study of NMHA

Fablication and

measurement of NMHA

Learning of FEKO (EM

Simulation)

Calculate resonant

structures at ε=εi µ=µi

(not Free Space)

Summarizesimulated results

Find out structural equation

March, April, May 2015

June, July, Aug, Sept

2015

Oct, Nov, Dec2015

Jan, Feb2016

March, April, May 2016

• Research Steps:

6. Present Situation

Caculation of Self-resonant Structure

Rin

Rl

Caculation of Input Resistance

Calculation of self-resonant structures and input resistance (in Free Space ε0)

7. Conclusion

• Now, fundamentals of NMHA are studying

• Next subject is to learn an electromagnetic simulator

• Obtain resonant structural data of NMHA in dielectric and

magnetic materials.

Thank you for your attention