Final tssa design and realization of passive phase shifters

Design and Realization of Passive Phase Shifter for Non Mechanical 1.8 GHz BTS Antenna Tilting

Dr.Ir.Joko Suryana

Andrian Agung, ST

Laboratory of Radio Telecommunications and Microwave

School of Electrical Engineering and Informatics ITB

1

Outline

• Abstract

• Antenna Tilting Concept – What, Why, How

• Research Design

• Design and Simulation– Array Antenna

– Passive Phase Shifter

• Implementation and Measurement

• Conclusions

3

Abstract• In this paper, we propose a low cost tilting control for

BTS antenna system based on passive phase shifter.

• The proposed BTS antenna has operating frequency at

1.8 GHz BTS

– This BTS antenna consists of 4 elements array.

– This antenna is designed with meander microstrip line and 0.4 λ

spacing and implemented on FR-4 substrate with permittivity 4.3.

• The phase shifter is implemented using Alumina which

has permittivity 9.4.

– The Alumina has higher permittivity than the antenna substrate

to cover each branch of transmission line of array antenna for

providing a non mechanical tilting control.

ANTENNA TILTING

What ?

• One of the most important aspects of BTS optimizationtasks is adjusting tilts, or the inclination of the antennain relation to an axis.

• With the tilt, we direct irradiation further down forconcentrating the energy in the new desired direction.

5

What ?• There are 2 tilting types :

– Mechanical tilt: Beam tilted by placement of the antenna with the help of mounting accessories.

– Non Mechanical or Electrical tilt: Beam tilted by varying the phase (using phase shifters)of the antenna elements

Why ?

• When we apply the tilt to an antenna :– we improve the signal in areas

close to the site; and – reduced the coverage in more

remote locations.

• In other words, when we're adjusting the tilt :– we seek a signal as strong as

possible in areas of interest (where the traffic must be), and ;

– similarly, a signal the weakest as possible beyond the borders of the cell.

How ?

• Mechanical tilt :– tilting the antenna by

physically adjusting the specific accessories on its bracket, without changing the phase of the input signal

• Electrical tilt :– Modification of the diagram is

obtained by changing thecharacteristics of signal phaseof each element of theantenna, as seen below.

How ?

Phase Shifter can be implemented in two

ways :

1. Active :

– Expensive

– Using active components

2. Passive :

– Cost efficient

Product ?

RET

RESEARCH DESIGN

Research Questions

• How to provide low cost non-mechanical tilting for BTS antenna ?

1. The passive phase shifter material should be available in Indonesia

2. The dimension of BTS antenna is not allowed bigger than before

3. The tilting angle is minimal 3 degree

13

Research Objectives

1. Designing and implementing BTS antenna model using 4-elements antenna array which has specific transmission lines for providing variable phase shifting function

2. Designing and implementing passive phase shifter based on Alumina substrate

3. Measuring the tilting performance of the implemented BTS antenna and its passive phase shifter

13

DESIGN AND SIMULATION : ARRAY ANTENNA

15

4-Elements Array Antenna : Standard Transmission Lines

• Frequency band : 1.8 GHz• Substrate= FR-4

• Thickness = 1.6 mm

• Patch dimension :

– L = 52,26 mm

– W = 37,75 mm

15

Port 2 SMA Connector

Rectangular Patch Antenna

Transmission Line

16

Simulation Results : Radiation Pattern and S11

16

DESIGN AND SIMULATION : PHASE SHIFTER

Substrate Choice

Substance Dielectric Constant Loss TangentAir 1.00054 0Alumina - 96% 10 0.0002 @ 1 GHzAlumina -99.5% 9.6 0.0002 @ 100 MHz

0.0003 @ 10 GHzFR-4 - low resin 4.9 0.008 @ 100 MHzFR-4 - high resin 4.2 0.008 @ 3 GHzGlass (Corning 7059) 5.75 0.0036 @ 10 GHzSilicon 11.7 - 12.9 0.005 @ 1 GHz

0.015 @ 10 GHzTeflon® (PTFE) 2.0 - 2.1 0.00028 @ 3 GHz

Substrate : Alumina

• Aluminium oxide is an amphotericoxide with the chemical formula Al2O3.

• It is commonly referred to as alumina (α-alumina), aloxide, or corundum in its crystalline form, as well as many other names, reflecting its widespread occurrence in nature and industry.

• Its most significant use is in the production of aluminium metal

• Although it is also used as an abrasive owing to its hardness and as a refractory material owing to its high melting point.

//upload.wikimedia.org/wikipedia/commons/c/c9/Aluminium_oxide2.jpg

Design and Simulation : Passive Phase Shifter

20

Tran

smis

sio

n L

ine

Alumina AluminaAlumina

Die

lect

ric

len

gth



Dielectric Length Effects

• The longer the dielectric material covering the microstrip line, the greater the resulting phase difference

21

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10111213141516171819202122

5 10 15 20 25 30 35 40 45 50 55

Ph

ase

Sh

ift

(de

gre

e)

Dielectric Length (mm)

Dielectric Thickness Effects

0123456789

10111213141516171819202122

5 10 15 20 25 30 35 40 45 50 55

Ph

ase

Sh

ift

(de

gre

e)

Dielectric length (mm)

selisih fasa tebal 0,1



• Thicker dielectric material, the greater the resulting phase

22

Permittivity Effects

0123456789

10111213141516171819202122232425

5 10 15 20 25 30 35 40 45 50 55

Ph

ase

Sh

ift

(de

gre

e)

Dielectric Length (mm)

permitivitas 9,4

permitivitas 20

permitivitas 48

permitivitas 60

• The higher value of the dielectric permittivity of the material used, the greater the resulting phase difference

23

24

Standard Transmission Lines With Passive Phase Shifter

24Port 2 SMA Connector


AluminaTransmission Line

25


25

DESIGN AND SIMULATION : MEANDER LINE

Meander Line

• From the simulation results we have seen that the longer thedielectric material covering the microstrip line, the greaterthe resulting phase difference– But it is not practical due to increasing the array antenna dimension

• So we need another approach to increase phase shift whilekeeping the BTS dimension same as before– We used Meander Line for extending the transmission line of each

branch while keeping the dimension

27

28

4-Elements Array Antenna : Meander Transmission Lines

• The length of meander lines = 29,3 mm

• Patch dimension:

– L = 52,26 mm

– W = 37,75 mm

28



Meander Line

29


29

30

Meander Transmission Lines With Passive Phase Shifter

3030



AluminaMeander Line

31


31

IMPLEMENTATION

32

32

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Two Model Implementation

• The antenna is implemented using FR-4 as the PCB with

copper ground plane.

• These following figures are the fabricated antennas that

have been combined with their passive phase shifters.

• First antenna model :

– 4-elements array antenna and passive phase shifter

with standard transmission lines

• Second antenna model :

– 4-elements array antenna and passive phase shifter

with meander transmission lines

34

Implemented Array Antenna and Passiver Phase Shifter : Standard

34

35

Implemented Array Antenna and Passiver Phase Shifter : Meander

35

MEASUREMENT SETUP

Antenna Measurements

• Return Loss Measurements

– For measuring the S11 parameters

– Using Vector Network Analyzer

• Radiation Pattern Measurements

– For measuring the radiation pattern with and without alumina-based phase shifter equipped to the array antennas

– Using Signal Generator, Spectrum Analyzer and Antenna Positioner

Return Loss Measurements

Block Diagram of Measurement Setup

VNA 0 – 3.5 GHz

Antenna ( DUT )

Radiation Pattern Measurements

Block Diagram of Measurement Setup

Radiation Pattern Measurements

Spectrum Analyzer

SignalGenerator

AntennaPositioner

MEASUREMENT VS DESIGN SIMULATION RESULTS

Simulation vs Measurement : S11

• Standard Transmission Lines

42-18.00

-16.00

-14.00

-12.00

-10.00

-8.00

-6.00

-4.00

-2.00

0.00

1.70 1.80 1.90 2.00

S11

(d

B)

Frekuensi (GHz)

pengukuran

simulasi

• There is a frequency operating

shift from 1.78 GHz (software

simulation) to 1.9 GHz (prototypemeasurement)


• Meander Transmission Lines

• Without passive phase shifter :

– The best S11 is -14.68 dB at the exact frequency is 1.802 GHz for simulation.

– In measurement, at 1.8 GHz, S11 is -10.68 dB.

43

-16.00

-14.00

-12.00

-10.00

-8.00

-6.00

-4.00

-2.00

0.00

1.70 1.80 1.90

S11

(d

B)

Frekuensi (GHz)

pengukuran

simulasi

Simulation vs Measurement : S11• Antenna –Standard Transmission Lines

with Alumina-based Phase Shifter

44

-20.00

-18.00

-16.00

-14.00

-12.00

-10.00

-8.00

-6.00

-4.00

-2.00

0.00

1.70 1.80 1.90 2.00

S11

(d

B)

Frekuensi (GHz)

pengukuran

simulasi

• There is a frequency operating

shift from 1.83 GHz (software

simulation) to 1.86 GHz (prototypemeasurement)


• Antenna –Meander Transmission Lines with Alumina-based Phase Shifter

• With passive phase shifter :

– The S11 is above -10 dB at frequency 1.8 GHz for the simulation

– The S11 is -12.45 dB at frequency 1.8 GHz for measurement 45

-20.00

-18.00

-16.00

-14.00

-12.00

-10.00

-8.00

-6.00

-4.00

-2.00

0.00

1.70 1.80 1.90

S11

(dB

)

Frekuensi (GHz)

pengukuran

simulasi

Radiation Patterns• Without Alumina

Standard Transmission Line Meander Line

-40.00

-35.00

-30.00

-25.00

-20.00

-15.00

-10.00

-5.00

0.00

04 8 1216202428

3236

4044

4852

5660

646872768084889296100104

108112

116120

124128

132136

140144

148152156160164168172176

180184188192196200204208

212216

220224

228232

236240

244248

252256260264268272276280284288292296

300304

308312

316320

324328

332336340344348352356

simulasi

pengukuran

46

-35.00

-30.00

-25.00

-20.00

-15.00

-10.00

-5.00

0.00

04 8 1216202428

3236

4044

4852

5660

646872768084889296100

104108

112116

120124

128132

136140

144148

152156160164168172176180

184188192196200204208212

216220

224228

232236

240244

248252

256260264268272276280284288292296

300304

308312

316320

324328

332336340344348352356SimulationMeasurement

Radiation Patterns• With Alumina

Standard Transmission Line Meander Line

-40.00

-35.00

-30.00

-25.00

-20.00

-15.00

-10.00

-5.00

0.00

04 8 1216202428

3236

4044

4852

5660

646872768084889296100104

108112

116120

124128

132136

140144

148152156160164168172176

180184188192196200204208

212216

220224

228232

236240

244248

252256260264268272276280284288292296

300304

308312

316320

324328

332336340344348352356

simulasi

pengukuran

47

-60.00

-50.00

-40.00

-30.00

-20.00

-10.00

0.00

04 8 1216202428

3236

4044

4852

5660

646872768084889296100104

108112

116120

124128

132136

140144

148152156160164168172176

180184188192196200204208

212216

220224

228232

236240

244248

252256260264268272276280284288292296

300304

308312

316320

324328

332336340344348352356SimulationMeasurement

Small Alumina sheet can be used

as low cost passive phase shifter

to give 0o-3.5o tilting control.

CONCLUSIONS

49

Conclusions

1. From our simulation and measurement results we can conclude that : – The tilting function has been demonstrated

successfully by using passive shifter based in alumina

2. From the simulation and measurement results we can also conclude that :

– Small Alumina sheet can be used as low cost passive phase shifter to give 0o-3.5o tilting control.

3. Moreover, these Alumina sheets which cover the transmission lines of the array antenna will also :

– Enhance the return loss of the array antenna.

THANK YOU

Final tssa design and realization of passive phase shifters

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