Supervised Undergraduate Thesis Andrian Agung

1. 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

2. 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.
3

4. ANTENNA TILTING

5. What ?
• One of the most important aspects of BTS optimization
tasks is adjusting tilts, or the inclination of the antenna
in relation to an axis.
• With the tilt, we direct irradiation further down for
concentrating the energy in the new desired direction.
5

6. 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

7. 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.

8. How ?
• Mechanical tilt : • Electrical tilt :
– tilting the antenna by – Modification of the diagram is
physically adjusting the obtained by changing the
specific accessories on its characteristics of signal phase
bracket, without changing the of each element of the
phase of the input signal antenna, as seen below.

9. How ?
Phase Shifter can be
implemented in two
ways :
1. Active :
–Expensive
– Using active
components
2. Passive :
– Cost efficient

10. Product ?
RET

11. RESEARCH DESIGN

12. 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
13

14. 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 Rectangular Patch Antenna
Transmission
Line
15
15
Port 2 SMA Connector

16. Simulation Results :
Radiation Pattern and S11
16
16

17. DESIGN AND SIMULATION :
PHASE SHIFTER

18. Substrate Choice
Substance Dielectric Constant Loss Tangent
Air 1.00054 0
Alumina - 96% 10 0.0002 @ 1 GHz
Alumina -99.5% 9.6 0.0002 @ 100 MHz
0.0003 @ 10 GHz
FR-4 - low resin 4.9 0.008 @ 100 MHz
FR-4 - high resin 4.2 0.008 @ 3 GHz
Glass (Corning 7059) 5.75 0.0036 @ 10 GHz
Silicon 11.7 - 12.9 0.005 @ 1 GHz
0.015 @ 10 GHz
Teflon® (PTFE) 2.0 - 2.1 0.00028 @ 3 GHz

19. Substrate : Alumina
• Aluminium oxide is an amphoteric
oxide 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.

20. Design and Simulation :
Passive Phase Shifter
Port 2 SMA Connector
Transmission Line
Dielectric length
Alumina
Alumina Alumina
Port 1 SMA Connector
20

21. Dielectric Length Effects
22
21
20
19
18
17
Phase Shift (degree)
16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
5 10 15 20 25 30 35 40 45 50 55
Dielectric Length (mm)
• The longer the dielectric material covering the
microstrip line, the greater the resulting phase
difference
21

22. Dielectric Thickness Effects
22
21
20
19
18
17
Phase Shift (degree)
16
15
14
13
12
11 selisih fasa tebal 0,1
10
9 selisih fasa tebal 0,7
8
7 selisih fasa tebal 0,05
6
5
4
3
2
1
0
5 10 15 20 25 30 35 40 45 50 55
Dielectric length (mm)
• Thicker dielectric material, the greater the
resulting phase
22

23. Permittivity Effects
25
24
23
22
21
20
19
Phase Shift (degree)
18
17
16
15
14 permitivitas 9,4
13
12
11 permitivitas 20
10
9
8 permitivitas 48
7
6 permitivitas 60
5
4
3
2
1
0
5 10 15 20 25 30 35 40 45 50 55
Dielectric Length (mm)
• 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
Rectangular Patch Antenna
Transmission Line
Alumina
24
Port 2 SMA Connector
24

25. Simulation Results :
Radiation Pattern and S11
25
25

26. DESIGN AND SIMULATION :
MEANDER LINE

27. Meander Line
• From the simulation results we have seen that the longer the
dielectric material covering the microstrip line, the greater
the resulting phase difference
– But it is not practical due to increasing the array antenna dimension
• So we need another approach to increase phase shift while
keeping 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: Rectangular Patch Antenna
– L = 52,26 mm
– W = 37,75 mm
Meander Line
28
Port 2 SMA Connector
28

29. Simulation Results :
Radiation Pattern and S11
29
29

30. Meander Transmission Lines With
Passive Phase Shifter
Rectangular Patch Antenna
Meander Line
Alumina
30
30
Port 2 SMA Connector
30

31. Simulation Results :
Radiation Pattern and S11
31
31

32. IMPLEMENTATION
32
32

33. 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
33

34. Implemented Array Antenna and
Passiver Phase Shifter : Standard
34
34

35. Implemented Array Antenna and
Passiver Phase Shifter : Meander
35
35

36. MEASUREMENT SETUP

37. 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

38. Return Loss Measurements
Antenna
( DUT )
Block Diagram of VNA 0 – 3.5 GHz
Measurement Setup

39. Radiation Pattern Measurements
Block Diagram of
Measurement Setup

40. Radiation Pattern Measurements
Spectrum Signal
Analyzer Generator
Antenna
Positioner

41. MEASUREMENT VS DESIGN
SIMULATION RESULTS

42. Simulation vs Measurement : S11
• Standard Transmission Lines
Frekuensi (GHz)
0.00
-2.00 1.70 1.80 1.90 2.00
-4.00
-6.00
S11 (dB)
-8.00 pengukuran
simulasi
-10.00
-12.00
• There is a frequency operating
-14.00
shift from 1.78 GHz (software
-16.00 simulation) to 1.9 GHz (prototype
-18.00 measurement)
42

43. Simulation vs Measurement : S11
• Meander Transmission Lines
Frekuensi (GHz)
0.00
-2.00 1.70 1.80 1.90
-4.00
-6.00
S11 (dB)
pengukuran
-8.00 simulasi
-10.00
• Without passive phase shifter :
-12.00 – The best S11 is -14.68 dB at
-14.00 the exact frequency is
1.802 GHz for simulation.
-16.00 – In measurement, at 1.8
GHz, S11 is -10.68 dB.
43

44. Simulation vs Measurement : S11
• Antenna –Standard Transmission Lines
with Alumina-based Phase Shifter
Frekuensi (GHz)
0.00
-2.001.70 1.80 1.90 2.00
-4.00
-6.00
-8.00
S11 (dB)
pengukuran
-10.00
simulasi
-12.00
-14.00
-16.00 • There is a frequency operating
-18.00
shift from 1.83 GHz (software
simulation) to 1.86 GHz (prototype
-20.00
measurement)
44

45. Simulation vs Measurement : S11
• Antenna –Meander Transmission Lines with
Alumina-based Phase Shifter
Frekuensi (GHz)
0.00
-2.00 1.70 1.80 1.90
-4.00
-6.00
-8.00 pengukuran
S11(dB)
-10.00 simulasi
-12.00
-14.00 • With passive phase shifter :
-16.00 – The S11 is above -10 dB at
-18.00 frequency 1.8 GHz for the
simulation
-20.00
– The S11 is -12.45 dB at
frequency 1.8 GHz for
measurement 45

46. Radiation Patterns
• Without Alumina
Standard Transmission Line Meander Line
356
0
4 8 12
Simulation 356
0
4 8 12
344 352
348 0.00 16 344 352
348 0.00 16
340
336
332
2024
28 Measurement 340
336
332
2024
28
328 -5.00 32 328 -5.00 32
324 36 324 36
320 40 320 40
316 -10.00 44 316 44
312 48 312 -10.00 48
308 -15.00 52 308 52
304 56 304 -15.00 56
300 -20.00 60 300 60
296 64 296 -20.00 64
292 -25.00 68 292 68
288 72 288 72
284 76 284 -25.00 76
-30.00
280 80 280 80
276 -35.00 84 276 -30.00 84
272 88 272 simulasi 88
268 -40.00 92 268 -35.00 92
pengukuran
264 96 264 96
260 100 260 100
256 104 256 104
252 108 252 108
248 112 248 112
244 116 244 116
240 120 240 120
236 124 236 124
232 128 232 128
228 132 228 132
224 136 224 136
220 140 220 140
216 144 216 144
212 148 212 148
208
204 152
156 208
204 152
156
200
196 188 160 200 160 46
192 184 172 164
176 168
196 188
192 184 172 164
176 168
180 180

47. Radiation Patterns
• With Alumina
Standard Transmission Line Meander Line
0
Simulation 356
0
4 8 12
356 4 8 12 344 352
348 0.00 16
344 352
340
348 0.00 1620 Measurement 340
336 2024
336 2428 332 28
332 328 32
328 -5.00 32 324 -10.00 36
324 36 320 40
320 40 316 44
316 -10.00 44 312 48
312 48 308 -20.00 52
308 -15.00 52 304 56
304 56 300 60
300 -20.00 60 -30.00
296 64 296 64
292 68 292 68
-25.00 288 -40.00 72
288 72
284 -30.00 76 284 76
280 80 280 -50.00 80
276 -35.00 84 276 84
272 88 272 simulasi 88
-40.00 268 -60.00 92
268 92 pengukuran
264 96 264 96
260 100 260 100
256 104 256 104
252 108 252 108
248 112 248 112
244 116 244 116
240 120 240 120
236 124 236 124
232 128 232 128
228
224
Small Alumina sheet can be used
132
136
228
224
132
136
220 140 220 140
216
212
208
as low cost passive phase shifter
144
148
152
216
212
208
144
148
152
204 156 o o 204 156
200
196 188
192 184
180
to give 0 -3.5 tilting control.
176 168
172
160
164 200
196 188
192 184
180
160
172 164
176 168 47

48. 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.
49

50. THANK YOU