Seminar

Introduction to Planar Antennas
2010.7.26@E-JUST

Kuniaki Yoshitomi
Graduate School of Information Science andElectrical Engineering (ISEE)

Kyushu University

Contents
1. Yoshitomi Lab Members and Research Plan
2. Basics of Antennas
3. Microstrip Patch Antenna
3-1 Basic Rectangular Patch Antenna
3-2 Slotted Patch Antenna (Broad Bandwidth)
3-3 Slotted Patch Antenna (Multifrequencies)
4. Monopole Antenna
4-1 Basic Square Monopole Antenna
4-2 Monopole Antenna with Notched Ground
4-3 Rounded Square Monopole Antenna
5. Measurement
6．Conclusion

Yoshitomi Lab
Students (Research)• D2 Yang (Small UWB antenna)• M2 Zhao (Small UWB antenna)
Kuramoto (Design of antenna using ANN)
Umekida (Scattering from decoupling capacitor, EMI)
• M1 Yoshioka (Miniaturization of antenna)• B4 Fukumoto (Design of antenna using ANN)
Tools
• Antenna simulator (HFSS)• Fortran software（FDTD program, ANN program)• Measurement facilities (VNA, anechoic chamber, etc.)Proposal of Research Subjects for PhD
or Master’s degree• Development of antennas using HFSS simulator
or FDTD program• Design of antennas using ANN (artificial neuralnetwork)
Small planar UWB antennas
Multiband patch antennas
One-sided directional antennas
Matching circuits for antennas
etc.
We will study antenna designs with various radiatorshapes, feeding structures, and matching circuits forbetter performance.

Example1: Small planar UWB antenna
10mm

3.12GHz – 17.0GHz
18mm

Ferrite core
Simulation Result-10dB Return Loss Bandwidth
3.1GHz – 14.9GHz

UWB(3.1 – 10.6 GHz)

Various antenna shapes and feeding structures
for better performance should be studied.

Example2: Multiband patch antenna
110mm

TM0160mm

1.973GHz

TM202.589GHz++---++Air substrate (height=6mm)
TM21
3.227GHz

TM313.770GHz---++- -+--++-+--+-+

Relation among slot size, feeding point location,and resonant frequencies has not been studied yet.

-Example3: One-sided directional antenna* Developed by Prof. Yoshida’s lab

yThe mechanism of one-sided radiation
has not beenstudied yet.
0Exp.

Return Loss [dB]-5
-1 0-1 5-2 0-2 5

Sim.

-3 0

Three resonance—broad band-3 56 .5

77 .5

88 .5
99 .5
F re q u e n c y [G H z ]101 0 .5

θ
φ =0°

7.25GHzφ =90°

8.25GHz

9.25GHzExample4: A matching circuit for
one-sided directional antenna* Developed by Prof. Yoshida’s lab

Photographs of the antenna019.3mm

Measured-10
Return Loss [dB]

J-Inverter(Inter digital gap)

Band width
-20
-30
-40

EM Sim.
-50

Antennas with this kind of matching circuit
have not been studied so much.

22.2

2.4
2.6
Frequency [GHz]2.83

Example5: Design of the antennausing an artificial neural network (ANN)An artificial neural network (ANN) for computing the return losses(Training method: Back propagation)

ANNs might be useful to optimize the antenna parameters.

An artificial neural network(ANN)•An artificial neural network (ANN), usually called "neural network"(NN), is a mathematical model or computational model that tries tosimulate the structure and/or functional aspects of biological neuralnetworks. It consists of an interconnected group of artificial neurons
and processes information using a connectionist approach tocomputation. In most cases an ANN is an adaptive system thatchanges its structure based on external or internal information thatflows through the network during the learning phase. Modern neuralnetworks are non-linear statistical data modeling tools. They areusually used to model complex relationships between inputs andoutputs or to find patterns in data. --- “Wikipedia”

Input:
Antenna parameters

Output:Return Loss

Publication List（Journal）[1] L.Lolit Kumar Singh, Bhaskar Gupta, Partha P Sarkar, K. Yoshitomi, and K. Yasumoto, “A Novel Versatile
Multiband Rectangular Patch Antenna,” Microwave and Optical Technology Letters, Vol.52, No.6,
pp.1348-1353, June, 2010.
[2] L.Lolit Kumar Singh, Bhaskar Gupta, Kuniaki Yoshitomi, and Kiyotoshi Yasumoto, “New Single Layer
Wideband Rectangular Patch Antenna,” The Special Issue of Asian Journal of Physics, Vol. 19, No.2、2009.（accepted）[3] Kuniaki Yoshitomi, “A Study on the Excitation and the Input Impedance of an Antenna,” The Special
Issue of Asian Journal of Physics, Vol. 19, No.2, 2009 .(accepted).
[5] Kuniaki Yoshitomi, “Radiation from a Slot Aperture in a Lossy Ground Plane,” Telecommunications andRadio Engineering, Vol.7, No.4-5, pp.85-92, 2002.
[6] Kuniaki Yoshitomi, “Radiation from a Slot in an Impedance Surface,” IEEE Transactions on Antennas andPropagation, Vol.49, No.10, pp.1370-1376, October 2001.
[7] Kiyotoshi Yasumoto and Kuniaki Yoshitomi, “Efficient Calculation of Lattice Sums for Free-Space
Periodic Green’s Function,” IEEE Transactions on Antennas and Propagation, Vol.47, No.6, pp.10501055, June 1999.
[8] Hongting.Jia, Kiyotoshi Yasumoto, and Kuniaki Yoshitomi, “Rigorous Analysis of E-/H-Plane Junctions in
Rectangular Waveguide Using Fourier Transform Technique,” Progress In Electromagnetics Research,Vol. PIER 21, pp.273-292, 1999.
[9] Hongting.Jia, Kiyotoshi Yasumoto, and Kuniaki Yoshitomi, “Rigorous Analysis of Rectangular Waveguide
Junctions by Fourier Transform Technique,” Progress In Electromagnetics Research, Vol. PIER 20,
pp.263-282, 1998.
[10] Kuniaki Yoshitomi, “Polarization Characteristics of the Radiation Field from an Aperture in an
Impedance Surface,” IEEE Transactions on Antennas and Propagation, Vol.44, No.11, pp.1464-1466,
November 1995.
[11] Youn S. Kim, Hyo J. Eom, Jae W. Lee, and Kuniaki Yoshitomi, “Scattering from Multiple Slits in a Thick
Conducting Plane,” Radio Science, Vol.30, No.5, pp.1341-1347, September-October 1995.

Publication List (Conference)[1] L.Lolit Kumar Singh, Bhaskar Gupta, Kiyotoshi Yasumoto, and Kuniaki Yoshitomi, “New Single Layer
Wideband Rectangular Patch Antennas,” Proceedings of 12th International Symposium on Microwave
and Optical technology, ISMOT-2009, December 2009.
[2] L.Lolit Kumar Singh, Bhaskar Gupta, Kiyotoshi Yasumoto, and Kuniaki Yoshitomi, “L-Shaped Slot
Broadband Single Layer Rectangular Patch Antennas,” Proceedings of 12th International Symposium onMicrowave and Optical technology, ISMOT-2009, December 2009.
[3] Kuniaki Yoshitomi, Bhaskar Gupta, and L.Lolit Kumar Singh, “A Study on Cross Slot Rectangular PatchAntenna,” Proceedings of International Symposium on Antennas and Propagation, ISAP2008, October
2008.
[4] Kuniaki Yoshitomi, “Transmission through an Aperture in a Plate with Surface Impedance in a
Rectangular Waveguide,” Proceedings of 10th International Symposium on Microwave and Opticaltechnology, ISMOT-2005, pp.87-90, August 2005.
[5] Kuniaki Yoshitomi, “Radiation from a Slot Aperture in a Lossy Ground Plane,” Proceedings andAbstracts of 2001 far-Eastern School-Seminar on Mathematical Modeling and Numerical Analysis,
FESS-MMNA’01, pp.227-232, August 2001.
[6] Hongting Jia, Kiyotoshi Yasumoto, and Kuniaki Yoshitomi, “Modified Perfectly Matched BoundaryConditions for Open Waveguide Structures,” Proceedings of 2000 International Conference on
Microwave and Millimeter Wave Technology, pp.287-290, September 2000.

Definition of Antenna
An antenna is a transition device, or transducer, between aguided wave and a free-space wave, or vice-versa.
J. D. Kraus and R. J. Marhefka,”Antennas,” McGraw-Hill. 2002.

Examples of Antennas
Five antennas are installedin the handset.

dipolepatch

Toshiba 911T

Basic Antenna Parameters
Antenna Performance Parameters• Radiation Pattern• Directivity• Gain• Polarization• Input Impedance• Bandwidth• Scanning :Movement of the radiation pattern in space• System Consideration :Size, weight, power handling, etc.
There are trade-offs between parameter values.
Performance cannot be improved significantly for one parameter
without sacrificing one or more of other parameter levels.
W.L.Stutzman and G.A.Thiele, ”Antenna Theory and Design,”
John Wiley & Sons, Inc. 1998.

Antenna Types

W.L.Stutzman and G.A.Thiele, ”Antenna Theory andDesign,” John Wiley & Sons, Inc. 1998.

Antenna can be divided into four basic types by
their performance as a function of frequency.
1. Electrically small antennas
The extent of the antenna structure is much smaller than awavelength λ .
Properties:
Examples:Very low directivity
Low input resistanceHigh input reactanceLow radiation efficiency(the most basic antenna) (dual of a short dipole)

Antenna Types
2. Resonant antennas
The antenna operates well at a single or selected narrow frequency
bands.
Properties:Low to moderate gain (a few dB)
Real input impedance
Narrow bandwidth
Examples:(a very widely used antenna)(printed antenna)

Antenna Types
3. Broadband antennas
The pattern, gain, and impedance remain acceptable and are nearly
constant over a wide frequency range.
Properties:
Low to moderate gain
Constant gain
Real input impedance
Wide bandwidth

Examples:Antenna Types
4. Aperture antennas
The antenna has a physical aperture (opening) through which waves flow.
Properties:
High gain (narrow main beam)Gain increases with frequency
Moderate bandwidthExamples:Antennas above a perfect ground plane
A direct ray

Radiation comes fromthe short section.
Transmission line

A reflected ray

Monopole antenna

Inverted-L antenna
Imageantenna

Monopole antenna:
A monopole is a dipole that has been divided in half at its center feed pointand fed against a ground plane.
(The image antenna acts as an equivalent source for the reflected ray.)Inverted-L antenna:
An inverted-L antenna is a transmission line loaded dipole.
(Low profile antenna)

Microstrip Patch Antennas
Feed

Equivalent magnetic surface currentAdvantages of Microstrip Patch Antennas• Low profile (The thickness is usually less than 0.03λ 0 .
λ 0 is the operating wavelength in free space.)• Light weight• Conformability to surface of substrates• Low cost
• Integration with other circuits• Versatility (A microstrip patch antenna is very versatile in termsof impedance, resonant frequency, radiation pattern, polarization,and operating mode, by choice of shape and feeding arrangement.)
Z.N.Chen and M.Y.W.Chia,”Broadband Planar Antennas,” Wiley, 2006.

Drawbacks of Microstrip Patch Antennas
in their basic forms• Narrow impedance bandwidth (typically of around 1%)• Poor polarization purity• Low radiation efficiency• Poor power capability• Poor scan performance• Excitation of surface waves
Much effort has been devoted to the developmentof broadband techniques.

Broadband techniques for
microstrip patch antennas
ApproachTechniques(1)Lower the Q

Select the radiator shape
Thicken the substrate
Lower the dielectric constant
Increase the losses(2)Use impedance matching
Insert a matching network
Add tuning elements
Use slotting and notching patches(3)Introduce multiple resonances Use parasitic elements
Use slotting patches
Insert impedance networks
Use an aperture, proximity coupling
Z.N.Chen and M.Y.W.Chia,”Broadband Planar Antennas,” Wiley, 2006.

A probe-fed rectangular microstrip patch antenna

ε eff : effective relative

Resonant frequency of TM mn mode2⎛⎞ ⎛⎞mn⎜⎜⎟⎟ + ⎜⎜⎟⎟
f mn =
2 ε eff ( L, W ) ⎝ L + 2ΔL(W ) ⎠ ⎝ W + 2ΔW ( L) ⎠c

Z.N.Chen and M.Y.W.Chia,”Broadband Planar Antennas,” Wiley, 2006.

2dielectric constant8c = 2.998 × 10 m/s: velocity of light

ΔL, ΔW : lengths offringing effectThe input impedance and return lossof a rectangular microstrip patch antenna

W = 76mm, L = 54mm, t = 1.5mm, ε r = 3.38

Current distributions of
the rectangular microstrip patch antenna

TM10TM01

TM11TM20

Bandwidth of the rectangular patch antenna•Thicker substrate•Lower dielectric constant
Broader bandwidth
W=L=54mm
Substrate thickness t=11.6mm,bandwitdh=8%(Radiation efficiency decreases.)

Substrate thickness t=1.5mm,bandwidth=0.7%

A probe-fed rectangular patch antenna(Introducing multiple resonances)
84.5mm72mm
0Return Loss (dB)

-5-10-15-20-25-30-35-40
1•Air substrate•Height h=11mm
Two resonances•Double slotBroadband

λr1 2 = 83.3mm
f r 2 = 2.2GHz λr 2 2 = 68.2mm
f r1 = 1.8GHz

23Frequency(GHz)41.73GHz - 2.26GHz
fc=1.995GHz-10dB bandwidth=26.6%

L.L.K.Singh, B.Gupta, K.Yasumoto, K.Yoshitomi, “Development of Novel Compact
Broadband and Multifrequency Patch Antennas on Air Substrate,”
4th Research Forum of Japan-Indo Collaboration Project, 2008.

5

Design of the antennausing an artificial neural network (ANN)An artificial neural network (ANN) for computing the return losses

Training method: Back propagation

A probe-fed rectangular patch antenna(Introducing multiple resonances)
Double I-slot patch antenna

Substrate (air dielectric) ε r = 1Thickness h = 7 mm (fixed)
W = 105mm, 110mm
L = 55mm, 60mm
Ls = 47.5mm (fixed)
Ws = 30mm, 35mm, 40mm
Training Data:
72 different sets of parameters and S11a = 7.5mm (fixed)b = 2.5mm, 5.0mm, 7.5mm,10.0mm, 12.5mm, 15.0mm

Result of ANN
Input:
105mm ≤ W ≤ 110mm

55mm ≤ L ≤ 60mm
30mm ≤ Ws ≤ 40mm
2.5mm ≤ b ≤ 15mm
Output: S11(fn)Forcenter frequency 2.0GHz
bandwidth 20%
W = 105.5mm, L = 55.5mm

Ws = 39mm, b = 11.25mm

FDTD simulation
fc= 2.059GHz
BW= 20.03%

Quad or tri frequency bands antennas(Introducing multiple resonances by using slot)

Quad frequency bands fed at F1

Tri frequency bands fed at F2

L.L.K.Singh, B.Gupta, K.Yasumoto, K.Yoshitomi, “Development of Novel Compact Broadband and Multifrequency
Patch Antennas on Air Substrate,” 4th Research Forum of Japan-Indo Collaboration Project, 2008.

Simulation of Electric Field Ez Distribution
Case2

Case1

TM01
1.973GHz

TM202.589GHz++---3.227GHz

TM313.770GHz++--- ++-- ++--+ +-+- -+2.020GHz

TM20+2.640GHz+
TM21

TM01---++- -+--++-+--+-+

TM21
3.220GHz-Resonance modes and frequencies

0°

Measured Radiation
30°
Patterns of Quad Bands
60°-60°
Antenna

-30°

-60°

-90°

90°
-30 -20 -10 00°
-30°

60°

-90°

90°

10 20-30 -20 -10 0

XZ-plane1
-120°

120°

TM01150° 1.90GHz-120°

TM202.56GHz

-150°

0°

0°
-30°

30°

60°

-90°

90°
-30-20-100YZ-plane2

60°

-90°

90°
-30 -20 -1010120°

150° 3.17GHz
-180°

01020

XZ-plane4

TM21
-150°

30°

-60°

XZ-plane2
-120°

150°
-180°

-60°

120°

YZ-plane3

-180°
-30°

10 20

XZ-plane3

XZ-plane1

-150°

30°

-120°

120°

YZ-plane4

TM31
3.53GHz

-150°

150°
-180°

0°
-30°

30°

-60°

Measured Radiation
Patterns of Tri Bands
Antenna60°-60°90°-90°-30 -20 -10 00°
-30°

60°

90°

-90°

10 20-30 -20 -10 0120°

YZ-plane1-150°

TM20150° 1.94GHz

2.58GHz

30°

-60°

60°

-90°

90°
-30 -20 -10 0

10 20

XZ-plane3
YZ-plane3

120°

TM21
150° 3.12GHz

-150°
-180°

120°

YZ-plane2

-150°

150°
-180°

0°

-120°

-120°

TM01
-180°

-30°

10 20

XZ-plane2

XZ-plane1
-120°

30°

Hexa, penta, quad or tri frequency
bands antennas
Frequency bands
Hexa bands
Penta bands
Quad bands
Tri bands

Feed point
F1F2F3F4

L.L.K.Singh, B.Gupta, K.Yasumoto, K.Yoshitomi, “Development of Novel Compact
Broadband and Multifrequency Patch Antennas on Air Substrate,” 4th Research Forum ofJapan-Indo Collaboration Project, 2008.

00-5-5Return Loss (dB)

Return Loss (dB)

Measured return losses of hexa, penta, quador tri frequency bands antennas-10-15-10-15Hexa bands

Penta bands-20-2023Frequency(GHz)45

100-5-5Return Loss (dB)

Return Loss (dB)

1-10-15

23Frequency(GHz)45-10-15

Quad bands

Tri bands-20-20123Frequency(GHz)45123Frequency(GHz)45

Planar monopole antenna 112mm
3.31GHz

Bandwidth 103%

10.41GHz

10mm
10mm

UWB(3.1GHz-10.6GHz)

18mm

2mm
7mm

3.5mm

FR4 (ε r = 4.4 )thickness=1.6mm

3GHz

10GHz

Planar monopole antenna 1
3GHz

Planar monopole antenna 1
10GHz

Planar monopole antenna 212mm

3.12 GHz - 12.73GHz
Bandwidth 120%

10mm
10mm
18mm

UWB(3.1GHz-10.6GHz)
2mm
7mm
3.5mm

FR4 ( ε r = 4.4 )thickness=1.6mm

M. Ojaroudi, C. Ghobadi, and J. Nourinia,”Small Square Monopole
Antenna With Inverted T-Shaped Notch in the Ground Plane for UWB
Application,” IEEE Antennas and Wireless Propagation Letters, Vol.8,
pp.728-731, 2009

Planar monopole antenna 312mm
3.5mm
2mm

2.8GHzBandwidth=136%

R18mm

UWB(3.1GHz-10.6GHz)

R=2mm
8mm
10mm

FR4 ( ε r = 4.4 )thickness=1.6mm

3GHz

14GHz

14.8GHzPlanar monopole antenna 33GHz

Planar monopole antenna 314GHｚ

Planar monopole antenna 46mm

3.5mm

Miniaturization by half-cut
1mm

3.4GHz Bandwidth=110% 11.8GHz

R18mm

R=2mm

UWB(3.1GHz-10.6GHz)

8mm
5mm

FR4 ( ε r = 4.4 )thickness=1.6mm

3GHz

12GHz

Planar monopole antenna 43GHz

Planar monopole antenna 412GHz

Planar monopole antenna 5(Prototype1)

12mm

3.1GHz(HFSS ver11.1)
3.3GHz(HFSS ver12)
Bandwidth=132%

3.5mm
3.2mm
16.5mmUWB(3.1GHz-10.6GHz)
R=1.7mm

10mm

FR4 ( ε r = 4.4 )thickness=1.6mm

16.2GHzPlanar monopole antenna 6(Prototype 2)
12mm
3.5mm

2mm
3.1GHzBandwidth=131%

RUWB(3.1GHz-10.6GHz)
18mm

R=2mm
8mm

10mm

FR4 ( ε r = 4.4 )thickness=1.6mm

14.9GHzMeasurement
Top Layer

Bottom Layer10mmnotch

SMA connector

antenna6antenna5

notch

SMA connector

antenna6antenna5

Return loss of antenna 5
4.6GHz – 17.9GHz

Ferrite core
Simulation Result-10dB Return Loss Bandwidth
3.3GHz – 16.2GHz

UWB(3.1 – 10.6 GHz)

Return loss of antenna 6
3.12GHz – 17.0GHz

Ferrite core
Simulation Result-10dB Return Loss Bandwidth
3.1GHz – 14.9GHz

UWB(3.1 – 10.6 GHz)

Conclusion
Proposal of Research Subjects for PhD or Master’s degree
Presented study• Basics of Antennas• Microstrip Patch Antennas
Basic Rectangular Patch Antenna
Slotted Patch Antenna (Broad Bandwidth)
Slotted Patch Antenna (Multifrequencies)• Monopole Antennas
Basic Square Monopole Antenna
Monopole Antenna with Notched Ground
Rounded Square Monopole Antenna• Measurement
Future study• Miniaturization of antennas• Metamaterial antennas, etc.

Thank you for your attention!