Post on 17-Jan-2020
Application Note:
Telink Antenna Design Guide
AN-16080500-E2
Ver 2.0.0
2018/12/17 TE
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Brief:
This document is the design guide for Telink common
antennas.
Telink Antenna Design Guide
AN-16080500-E2 1 Ver 2.0.0
Published by Telink Semiconductor
Bldg 3, 1500 Zuchongzhi Rd,
Zhangjiang Hi-Tech Park, Shanghai, China © Telink Semiconductor
All Right Reserved
Legal Disclaimer
Telink Semiconductor reserves the right to make changes without further notice to
any products herein to improve reliability, function or design. Telink Semiconductor
disclaims any and all liability for any errors, inaccuracies or incompleteness contained
herein or in any other disclosure relating to any product.
Telink Semiconductor does not assume any liability arising out of the application or
use of any product or circuit described herein; neither does it convey any license
under its patent rights, nor the rights of others
The products shown herein are not designed for use in medical, life-saving, or
life-sustaining applications. Customers using or selling Telink Semiconductor products
not expressly indicated for use in such applications do so entirely at their own risk
and agree to fully indemnify Telink Semiconductor for any damages arising or
resulting from such use or sale.
Information:
For further information on the technology, product and business term, please
contact Telink Semiconductor Company (www.telink-semi.com).
For sales or technical support, please send email to the address of:
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Telink Antenna Design Guide
AN-16080500-E2 2 Ver 2.0.0
Revision History
Version Major Changes Date Author
1.0.0 Initial release 2016/8 H.Z.F., L.X., Cynthia
2.0.0
Updated based on
“AN_16080500-E1_Telink Antenna Design
Guide” and “AN_A-PCB-E3_Common
Antennas”.
Added section 1 Overview,
2 Brief Introduction about Antenna,
3 Antenna Type,
4 Matching Bandwidth, RL with a Network
Analyzer.
2018/12 L.X., Cynthia
Telink Antenna Design Guide
AN-16080500-E2 3 Ver 2.0.0
Table of contents
1 Overview ................................................................................................................. 5
2 Brief Introduction about Antenna .......................................................................... 5
3 Antenna Type .......................................................................................................... 8
4 Matching Bandwidth, RL with a Network Analyzer ................................................ 9
5 Antenna Simulation Sample 1 .............................................................................. 11
5.1 Module figure ................................................................................................ 11
5.2 S11 figure ....................................................................................................... 11
5.3 Radiation figure .............................................................................................. 12
5.4 Antenna description log ................................................................................. 13
6 Antenna Simulation Sample 2 .............................................................................. 14
6.1 Module figure ................................................................................................ 14
6.2 S11 figure ....................................................................................................... 14
6.3 Radiation figure .............................................................................................. 15
6.4 Antenna description log ................................................................................. 16
7 Antenna Simulation Sample 3 .............................................................................. 17
7.1 Module figure ................................................................................................ 17
7.2 S11 figure ....................................................................................................... 17
7.3 Radiation figure .............................................................................................. 18
7.4 Antenna description log ................................................................................. 19
8 Small-Dimension Antennas .................................................................................. 20
8.1 Sample 1 ......................................................................................................... 20
8.2 Sample 2 ......................................................................................................... 21
Telink Antenna Design Guide
AN-16080500-E2 4 Ver 2.0.0
Table of figures
Figure 1 Typical emission pattern forλ/2 dipole antenna ................................... 5
Figure 2 Mounting cable ...................................................................................... 9
Figure 3 Calibrate vector network analyzer....................................................... 10
Figure 4 Module figure 1 ................................................................................... 11
Figure 5 S11 figure 1 .......................................................................................... 11
Figure 6 Radiation figure 1 ................................................................................ 12
Figure 7 Module figure 2 ................................................................................... 14
Figure 8 S11 figure 2 .......................................................................................... 14
Figure 9 Radiation figure 2 ................................................................................ 15
Figure 10 Module figure 3 ................................................................................ 17
Figure 11 S11 figure 3 ...................................................................................... 17
Figure 12 Radiation figure 3 ............................................................................. 18
Figure 13 Sample 1 ........................................................................................... 20
Figure 14 Sample 2 ........................................................................................... 21
Telink Antenna Design Guide
AN-16080500-E2 5 Ver 2.0.0
1 Overview
Antenna is the most important component used in short-range device
applications.
In this document, many important parameters, e.g. bandwidth, gain, impedance
matching parameters, will be introduced.
It is very important to use a correct antenna pattern. In free space, wavelength
(λ) is about 12cm~12.5cm.
2 Brief Introduction about Antenna
Antenna is an important component to transmit higher power and receive a
weak signal.
A typical antenna used in consumer electronics is 1/4 wavelength antenna. And
1/2 wavelength dipole is usually used during initial design.
a) λ/2 dipole antenna
A dipole antenna is often designed asλ/2 wavelength. The Figure 1 shows the
typical emission pattern.
Figure 1 Typical emission pattern forλ/2 dipole antenna
The antenna is located in the Z plane. The most powerful energy is radiated out
in the XY plane. The weakest points are on the Z plane.
Telink Antenna Design Guide
AN-16080500-E2 6 Ver 2.0.0
b) Monopole (λ/4) antenna
A monopole antenna is often designed asλ/4 wavelength, and it’s often used in
applications including consumer electronics and IOT.
Since one antenna element isλ/4 wavelength and the GND plane acts as the
otherλ/4 wavelength, theλ/4 wavelength monopole antenna is equal to aλ/2
wavelength dipole antenna in fact.
Usually, a big solid ground is necessary for good antenna performance.
c) Voltage Standing Wave Ratio (VSWR)
In theory, when the source resistance is equal to the load resistance, the load
will get the maximum power from the source.
Z0 = Zl
The complex reflection coefficient(Γ) is defined as below.
Γ = (Zl-Z0)/(Zl+Z0)
If Zl=Z0,Γ=0, then the load gets the maximum energy.
In antenna applications, VSWR and Return Loss (RL) are usually used.
VSWR=(1+|Γ|)/(1-|Γ|)
S11(db)=20log((VSWR-1)/(VSWR+1))
VSWR and RL are used to check how well the antenna works. Usually, VSWR 0f
2.0(RL=9.5dB) is usually used as the limitation to define antenna’s bandwidth. In
real application design, it’s recommended to adopt a pi-matching network.
Table 1 VSWR, RL and Γ
VSWR Return Loss (dB) Reflection Coefficient
1 ∞ 0
1.5 14 0.2
2 9.5 0.333
Telink Antenna Design Guide
AN-16080500-E2 7 Ver 2.0.0
d) Antenna parameters
When choosing a correct antenna pattern, it’s needed to consider many
parameters, including:
i. Antenna location: Do not place antenna close to metal components, motor,
battery and so on. Please place antenna face to free space.
ii. Ground plane: A big and solid ground is a fundamental design point to
ensure good antenna performance.
iii. Matching network: A pi-matching network is optional in the design.
iv. Antenna gain: In consumer applications, omnidirectional antenna is a good
choice.
v. Antenna bandwidth: The parameter is defined using Return Loss.
e) Friis transmission equation
Friis transmission equation is a primary formula to estimate power and distance.
When the transmitted power increases by delta (unit: dBm), the communication
distance will be the X multiple.
For example, when increasing power by 6dBm, the communication distance will
double.
△(dBm) X (Multiple)
3 1.4
6 2
Telink Antenna Design Guide
AN-16080500-E2 8 Ver 2.0.0
3 Antenna Type
Size and cost are parameters that should be considered together when choosing
antenna.
Table 2 Advantage and disadvantage for different antenna types
Antenna Type Advantage Disadvantage
PCB antenna
low cost;
small size at high frequencies;
wide bandwidth available when
designed well
large size at low frequencies
Chip antenna small size high cost;
narrow bandwidth
Whip antenna high performance high cost;
large volume
Telink Antenna Design Guide
AN-16080500-E2 9 Ver 2.0.0
4 Matching Bandwidth, RL with a Network Analyzer
a) Mounting cable for S11 measurement
It is very important to use semi-rigid cables when doing RF measurement.
Solder the outer of the cable to ground plane, and solder the inner of the cable
to the feed point.
Figure 2 Mounting cable
b) Calibration
It is important to calibrate the network analyzer before doing RF measurement.
We usually do it like this.
i. Choose a suitable calibration kit.
ii. Set the correct frequency range.
iii. Set several markers.
iv. Connect three known terminations, 50 ohm load, short and open, to the
connector.
v. Move the calibration plane to the feed point by using calibration
extension function.
Telink Antenna Design Guide
AN-16080500-E2 10 Ver 2.0.0
And ferrites MUST be used to reduce the influence from current running at the
outer of the cable. This point is very important, and it’s highly recommended to
follow it.
Figure 3 Calibrate vector network analyzer
c) Antenna under test
The antenna should be placed in the real case when measuring return loss.
For example, if the device is a remote controller, you should measure return loss
with the actual usage case. Since remote controller is handhold, it’s
recommended to take it by your hand when measuring.
d) Impedance matching
Usually Vector network analyzer (VNA) is used to tune an antenna.
Antenna type, ground size, and distance from antenna to ground are the
parameters that can affect the impedance. By changing them, it is possible to
improve the impedance.
Discreet components can also be used to tune antenna by smith chart on VNA.
Telink Antenna Design Guide
AN-16080500-E2 11 Ver 2.0.0
5 Antenna Simulation Sample 1
5.1 Module figure
Figure 4 shows dimensions of a module board (Dual-layer FR4, board thickness
is 1mm) and combined antenna.
The maximum gain for this antenna is 3dBi or so.
Figure 4 Module figure 1
5.2 S11 figure
Figure 5 shows S11 figure.
Figure 5 S11 figure 1
2.20 2.30 2.40 2.50 2.60 2.70Freq [GHz]
-27.50
-25.00
-22.50
-20.00
-17.50
-15.00
-12.50
-10.00
-7.50
dB
(St(
An
ten
nn
a_
T1
,An
ten
nn
a_
T1
))
HFSSDesign1XY Plot 1 ANSOFT
m1
m2
m3
Curve Info
dB(St(Antennna_T1,Antennna_T1))Setup1 : Sw eep
Name X Y
m1 2.4000 -22.9083
m2 2.4500 -26.3755
m3 2.5000 -21.2613
Telink Antenna Design Guide
AN-16080500-E2 12 Ver 2.0.0
5.3 Radiation figure
Figure 6 shows radiation figure.
Figure 6 Radiation figure 1
Telink Antenna Design Guide
AN-16080500-E2 13 Ver 2.0.0
5.4 Antenna description log
1. External view drawing
Picture of antenna
2. Antenna Radiation Pattern
ZX plane ZY plane XY plane
Frequency Max Value Average Max Value Average Max Value Average
[MHz] [dBi] [dBi] [dBi] [dBi] [dBi] [dBi]
2400 3.09 1.77 2.84 -2.5 3.12 -3.71
2450 2.95 1.82 2.92 -2.59 3.06 -3.75
2500 3.18 1.71 2.83 -2.42 3.28 -3.55
Radiation Pattern XOZ Radiation Pattern YOZ Radiation Pattern XOY
Telink Antenna Design Guide
AN-16080500-E2 14 Ver 2.0.0
6 Antenna Simulation Sample 2
6.1 Module figure
Figure 7 shows dimensions of a module board (Dual-layer FR4, board thickness
is 1mm) and combined antenna.
The maximum gain for this antenna is 2dBi or so.
Figure 7 Module figure 2
6.2 S11 figure
Figure 8 shows S11 figure.
Figure 8 S11 figure 2
2.20 2.30 2.40 2.50 2.60 2.70Freq [GHz]
-22.50
-20.00
-17.50
-15.00
-12.50
-10.00
-7.50
-5.00
-2.50
0.00
dB
(St(
An
ten
nn
a_
T1
,An
ten
nn
a_
T1
))
HFSSDesign1XY Plot 1 ANSOFT
m1
m2
m3
Curve Info
dB(St(Antennna_T1,Antennna_T1))Setup1 : Sw eep
Name X Y
m1 2.4000 -10.9265
m2 2.4500 -21.3129
m3 2.5000 -12.4859
Telink Antenna Design Guide
AN-16080500-E2 15 Ver 2.0.0
6.3 Radiation figure
Figure 9 shows radiation figure.
Figure 9 Radiation figure 2
Telink Antenna Design Guide
AN-16080500-E2 16 Ver 2.0.0
6.4 Antenna description log
1. External view drawing:
Picture of antenna
3. Antenna Radiation Pattern
ZX plane ZY plane XY plane
Frequency Max Value Average Max Value Average Max Value Average
[MHz] [dBi] [dBi] [dBi] [dBi] [dBi] [dBi]
2400 2.18 1.68 2.18 -3.17 1.78 -3.43
2450 2.23 1.77 2.21 -3.18 1.78 -3.46
2500 2.13 1.70 2.13 -3.27 1.58 -3.52
Radiation Pattern XOZ Radiation Pattern YOZ Radiation Pattern XOY
Telink Antenna Design Guide
AN-16080500-E2 17 Ver 2.0.0
7 Antenna Simulation Sample 3
7.1 Module figure
Figure 10 shows dimensions of a module board (Dual-layer FR4, board thickness
is 1mm) and combined antenna.
The maximum gain for this antenna is 3dBi or so.
Figure 10 Module figure 3
7.2 S11 figure
Figure 11 shows S11 figure.
Figure 11 S11 figure 3
2.20 2.30 2.40 2.50 2.60 2.70Freq [GHz]
-22.00
-20.00
-18.00
-16.00
-14.00
-12.00
-10.00
dB
(St(
An
ten
nn
a_
T1
,An
ten
nn
a_
T1
))
HFSSDesign1XY Plot 1 ANSOFT
m4
m5
m6
Curve Info
dB(St(Antennna_T1,Antennna_T1))Setup1 : Sw eep
Name X Y
m4 2.4000 -18.6059
m5 2.4400 -19.9247
m6 2.5000 -21.0839
Telink Antenna Design Guide
AN-16080500-E2 18 Ver 2.0.0
7.3 Radiation figure
Figure 12 shows radiation figure.
Figure 12 Radiation figure 3
Telink Antenna Design Guide
AN-16080500-E2 19 Ver 2.0.0
7.4 Antenna description log
1.External view drawing:
Picture of antenna
2.Antenna Radiation Pattern
ZX plane ZY plane XY plane
Frequency Max Value Average Max Value Average Max Value Average
[MHz] [dBi] [dBi] [dBi] [dBi] [dBi] [dBi]
2400 2.91 2.09 2.93 -3.00 2.67 -4.14
2450 2.83 2.13 2.78 -3.12 2.81 -4.13
2500 2.95 2.07 2.87 -3.00 2.89 -4.05
Radiation Pattern XOZ Radiation Pattern YOZ Radiation Pattern XOY
0.60
1.20
1.80
2.40
90
60
30
0
-30
-60
-90
-120
-150
-180
150
120
HFSSDesign1XOZ ANSOFT
Curve Info max avg
Freq='2.45GHz' Phi='0deg' 2.9088 2.0909
Freq='2.4GHz' Phi='0deg' 2.8336 2.1312
Freq='2.5GHz' Phi='0deg' 2.9462 2.0705
-11.00
-7.00
-3.00
1.00
90
60
30
0
-30
-60
-90
-120
-150
-180
150
120
HFSSDesign1YOZ ANSOFT
Curve Info max avg
Freq='2.45GHz' Phi='90deg' 2.9354 -3.0085
Freq='2.4GHz' Phi='90deg' 2.7809 -3.1230
Freq='2.5GHz' Phi='90deg' 2.8668 -2.9999
-19.00
-13.00
-7.00
-1.00
90
60
30
0
-30
-60
-90
-120
-150
-180
150
120
HFSSDesign1XOY ANSOFT
Curve Info max avg
Freq='2.45GHz' Theta='90deg' 2.6711 -4.1401
Freq='2.4GHz' Theta='90deg' 2.8128 -4.1306
Freq='2.5GHz' Theta='90deg' 2.8940 -4.0575
Telink Antenna Design Guide
AN-16080500-E2 20 Ver 2.0.0
8 Small-Dimension Antennas
The two types of antennas shown in this section apply to applications with
requirement for highly limited board size (e.g. dongle and module). In actual
applications, as long as board size allows, it’s recommended to adopt antenna with
larger area for better performance.
8.1 Sample 1
Figure 13 Sample 1
Telink Antenna Design Guide
AN-16080500-E2 21 Ver 2.0.0
8.2 Sample 2
Figure 14 Sample 2