Projects:2015s1-28 Wireless Rotation Detector - Revision history

A1615563: /* 1.Method */

2015-10-23T00:59:50Z

‎1.Method

A1615563: /* 2.Experiment & Result */

2015-10-23T00:56:23Z

‎2.Experiment & Result

A1615563: /* Entire System Test */

2015-10-22T10:54:53Z

‎Entire System Test

A1615563: /* Software Design */

2015-10-22T10:51:44Z

‎Software Design

A1615563: /* Antenna Design */

2015-10-22T10:50:29Z

‎Antenna Design

A1615563: /* Entire System Test */

2015-10-22T10:46:55Z

‎Entire System Test

A1615563: /* Antenna Design */

2015-10-22T10:45:46Z

‎Antenna Design

A1615563: /* Discussion */

2015-10-22T10:43:01Z

‎Discussion

A1615563: /* Metamaterial Absorber Design */

2015-10-22T10:42:14Z

‎Metamaterial Absorber Design

A1615563: /* Metamaterial Absorber Design */

2015-10-22T10:40:11Z

‎Metamaterial Absorber Design

@@ Line 193: / Line 193: @@
 After some unsuccessful trials, we finally presented the design of the metamaterial absorber operating at 2.4 GHz by using a via. A unit cell of proposed absorber is shown in Figure 7. It is a 3 layer structure which has a metallic loop at the top, a ground plane and a substrate in between. A 150Ω resistive load is used as a via to connect the top and bottom layer. The absorber is designed to operate at 2.4 GHz with the optimized dimensions given by a1=20mm, a=16mm, b1=19mm, b=13.4mm, w1=4, w2=2.6mm.
-[[File:A schematic showing the proposed unit cell of metamaterial absorber.PNG|400px|thumb|center|Figure 6.A schematic showing the proposed unit cell of metamaterial absorber]]
+[[File:A schematic showing the proposed unit cell of metamaterial absorber.PNG|400px|thumb|center|Figure 6a.A schematic showing the proposed unit cell of metamaterial absorber]]
 The unit cell was hosted on the top of a 3.2mm thick FR-4 dielectric substrate with a loss tangent of 0.025 and a dielectric constant of εr=4.4. The simulation for ELC resonator was performed with a full-wave electromagnetic simulator, Ansoft HFSS. The unit cell was placed in a waveguide with Master and Slave boundary condition. The boundary condition was selected for the unit cell in order to realize TEM mode excitation with polarization shown in Figure 7.
@@ Line 208: / Line 210: @@
 The reason why the design can successfully absorb power can be analysed by the surface current distribution, as shown in Figure 8. From the graph, we can observe that the surface current is mainly distributed at the middle of the left and right side of metallic loop. Meanwhile, the surface current at the top and bottom is minimal.
 However, the voltage at the surface will be distributed conversely. The voltage at top and bottom of the metallic loop is maximum while that at middle of left and right side is minimum. Therefore, connecting the top layer and ground plane with a resistive load enables the current to flow through the resistor due to the voltage difference, resulting in the power dissipation.
 === 2.Experiment & Result ===

@@ Line 219: / Line 219: @@
 [[File:A schematic for absorber experiment.PNG|400px|thumb|center|Figure 9.A schematic for absorber experiment]]
 The absorber was placed in middle front of the 2 antennas. In order to ensure the accuracy of the measurement, the distance between the absorber and the antennas was 140 cm to avoid the near-field effects. However, the transmitting and receiving antennas would have incident angle of 8.13º with respect to the surface of the absorber plane due to the experiment limitations.
@@ Line 233: / Line 234: @@
 Figure 11 shows the reflection coefficient for the cross-polarized direction. We can observe that the reflection coefficient for both simulation and measurement is 0 at 2.4 GHz, which means the absorber can reflect 100% incident power when cross-polarized. In addition, both results show that the resonant frequency at around 3.25 GHz. The difference between simulated and measured minimum reflect coefficients may result from the unwanted edge scattering caused by the finite array of unit cell
 === Discussion ===

← Older revision		Revision as of 10:54, 22 October 2015
Line 431:		Line 431:

	Table 12 provides the information about the operational distance. From the table, it can be concluded that the maximum distance for the system is roughly 70 cm. Given that the operating distance for the original system was 57 cm [2], the system has already been improved from the respective of the operating distance.		Table 12 provides the information about the operational distance. From the table, it can be concluded that the maximum distance for the system is roughly 70 cm. Given that the operating distance for the original system was 57 cm [2], the system has already been improved from the respective of the operating distance.
		+
		+
		+	== Conclusion ==
		+
		+	The thesis provides the information about the introduction, system design, experiment and result analysis of the wireless rotation detector project. The main objective of this year project is to enhance the performance of the absorber and modify the structure of antenna.
		+	For the absorber design, the metamaterial absorber has the resonant frequency at 2.52 GHz with 99.68% absorptivity. The bandwidth of the absorber is 0.17 GHz, which has been significantly enhanced compared to the simulated result (0.03 GHz) from last year. The potential cause for the resonant frequency shift is also discussed in section 6.1, so current structure of the absorber can be modified with the consideration of resistors’ RF behaviour in order to achieve 2.4 GHz resonant frequency. Overall, the absorber design has successfully met the specifications we proposed at the beginning of the project.
		+
		+	On the part of antenna design, the performance of dual patch antennas is acceptable for our project. The reflection coefficient of dual patch antennas is around a low value at resonate frequency and ensure more than 90% power can be transmitted. The challenge for antenna design is keeping the antenna system in a plane and reducing the coupling less than -40dB. So the isolation technology of a reverse phase coupling has been introduced. So this technology has reduced the coupling between two patch antennas less than -40dB, which can ensure that the transmitting signal would not affect the reading.
		+
		+	The requirements about the accuracy and the operating distance of the entire system have also been reached. The entire system can measure the rotation speed within 4% error compared to the commercial product, Tachometer. In addition, the operating distance is also increased from 57 cm to 70 cm under test environment.
		+	Overall, the objectives of the project have been achieved and the entire system could be useful for future industrial applications.

	== Reference ==		== Reference ==

@@ Line 400: / Line 400: @@
 The main principle used for the calculation algorithm is Fast Fourier Transform (FFT). According to the discussion in Section 1.2, the reflected power shall periodically vary from 0 to maximum due to the polarization loss. Therefore, FFT transforms the received power in time-domain to frequency-domain and the fundamental frequency of the frequency-domain signal provides the information of the rotation speed. The calculation algorithm is reused from the previous design.
-[[File:16×2 LCD keypad shield for Arduino.PNG|400px|thumb|center|Figure 22.16×2 LCD keypad shield for Arduino]]
+[[File:16×2 LCD keypad shield for Arduino.PNG|400px|thumb|center|Figure 27.16×2 LCD keypad shield for Arduino]]
-By contrast, the user interface is adapted this year to display different information. A 16×2 bit LCD keypad is connected to the Arduino UNO board. From Figure 10, it is interesting to note that there are 6 buttons available in the LCD keypad shield. However, only Left, Top, Bottom and Right are used for the message display.
+By contrast, the user interface is adapted this year to display different information. A 16×2 bit LCD keypad is connected to the Arduino UNO board. From Figure 27, it is interesting to note that there are 6 buttons available in the LCD keypad shield. However, only Left, Top, Bottom and Right are used for the message display.
 The functionality of the user interface is listed as follows:

@@ Line 325: / Line 325: @@
 '''Simulated result:'''
-[[File:Reflection coefficient & coupling effect for dual patch antennas.PNG|400px|thumb|center|Figure 11.Reflection coefficient & coupling effect for dual patch antennas]]
+[[File:Reflection coefficient & coupling effect for dual patch antennas.PNG|400px|thumb|center|Figure 16.Reflection coefficient & coupling effect for dual patch antennas]]
 '''Measured results:'''
@@ Line 332: / Line 332: @@
-[[File:Measured reflection coefficient for dual patch antennas.PNG|400px|thumb|center|Figure 16.Measured reflection coefficient for dual patch antennas]]
+[[File:Measured reflection coefficient for dual patch antennas.PNG|400px|thumb|center|Figure 17.Measured reflection coefficient for dual patch antennas]]
-[[File:Measured coupling effect for dual patch antennas.PNG|400px|thumb|center|Figure 17.Measured coupling effect for dual patch antennas ]]
+[[File:Measured coupling effect for dual patch antennas.PNG|400px|thumb|center|Figure 18.Measured coupling effect for dual patch antennas ]]
 ''Comparison:''
@@ Line 344: / Line 344: @@
 * Dual patch antennas with ‘U’ structure:
 Using ‘U’ structure between two antennas, the following figures illustrate simulated result of reflection coefficient and coupling effect as well as measured.
-The figure 16 and figure 17 illustrate prototype of dual patch antennas with ‘U’ structure
+The figure 20 and figure 21 illustrate prototype of dual patch antennas with ‘U’ structure
-[[File:Simulated results with measured results.PNG|400px|thumb|center|Figure 18.Simulated results with measured results]]
+[[File:Simulated results with measured results.PNG|400px|thumb|center|Figure 19.Simulated results with measured results]]
-[[File:Top view of dual antennas.png|400px|thumb|center|Figure 19.Top view of dual antennas]]
+[[File:Top view of dual antennas.png|400px|thumb|center|Figure 20.Top view of dual antennas]]
-[[File:Bottom view of dual antennas.png|400px|thumb|center|Figure 20.Bottom view of dual antennas]]
+[[File:Bottom view of dual antennas.png|400px|thumb|center|Figure 21.Bottom view of dual antennas]]
 ''Comparison:''
-From figure 15, after using ‘U’ structure between two patch antennas, the reflection coefficient of simulated is around -19dB at resonate frequency 2.4GHz and measured reflection coefficient is around -24dB at 2.4GHz. Those two results are similar with each other and the performance is acceptable.
+From figure 19, after using ‘U’ structure between two patch antennas, the reflection coefficient of simulated is around -19dB at resonate frequency 2.4GHz and measured reflection coefficient is around -24dB at 2.4GHz. Those two results are similar with each other and the performance is acceptable.
 For the crosstalk efficient, the crosstalk efficient of simulated at resonate frequency is around -43.3dB and the measured crosstalk efficient is -45dB at 2.4GHz. Those two result are close to each other and it is obviously that the coupling between two patch antennas has been reduced dramatically compared with the without ‘U’ structure case. Also from the figure 15, the simulated curve of reflection coefficient overlap the measured one and crosstalk curve of simulated and measured are also similar with each one. The performance of dual patch antennas has met the requirement. The details of principle of ‘U’ will be discussed in next section.
-[[File:Radiation Pattern for dual antennas in E-plane.PNG|400px|thumb|center|Figure 21.Radiation Pattern for dual antennas in E-plane]]
+[[File:Radiation Pattern for dual antennas in E-plane.PNG|400px|thumb|center|Figure 22.Radiation Pattern for dual antennas in E-plane]]
-[[File:Radiation Pattern for dual antennas in H-plane.PNG|400px|thumb|center|Figure 22.Radiation Pattern for dual antennas in H-plane]]
+[[File:Radiation Pattern for dual antennas in H-plane.PNG|400px|thumb|center|Figure 23.Radiation Pattern for dual antennas in H-plane]]
-[[File:Radiation Pattern for dual antennas.PNG|400px|thumb|center|Figure 23.Radiation Pattern for dual antennas]]
+[[File:Radiation Pattern for dual antennas.PNG|400px|thumb|center|Figure 24.Radiation Pattern for dual antennas]]
-From figure 21 to figure 23, they demonstrate measured radiation pattern for two patch antennas with ‘U’ structure. All the radiation patterns were measured in the echoic chamber. The two patch antennas system was measured from -180 degree to 180 degree and the measured frequency at 2.4GHz with 1601 sweep points. From the figure 23, it is obviously that the maximum gain in E-plane and H-plane are at 0 degree. So the performance is acceptable and this design has satisfied with the requirement of the project.
+From figure 22 to figure 24, they demonstrate measured radiation pattern for two patch antennas with ‘U’ structure. All the radiation patterns were measured in the echoic chamber. The two patch antennas system was measured from -180 degree to 180 degree and the measured frequency at 2.4GHz with 1601 sweep points. From the figure 23, it is obviously that the maximum gain in E-plane and H-plane are at 0 degree. So the performance is acceptable and this design has satisfied with the requirement of the project.
 ''Results summary:''
@@ Line 386: / Line 386: @@
 This section will focus on some physical explanations about the ‘U’ structure and explain the reason why the ‘U’ structure can reduce the coupling between two patch antennas.
-[[File:Simulated and Measured S21 for dual antennas in different conditions.PNG|400px|thumb|center|Figure 24.File:Simulated and Measured S21 for dual antennas in different conditions]]
+[[File:Simulated and Measured S21 for dual antennas in different conditions.PNG|400px|thumb|center|Figure 25.File:Simulated and Measured S21 for dual antennas in different conditions]]
-[[File:Schematic for ‘U’ structure.PNG|400px|thumb|center|Figure 25.Schematic for ‘U’ structure]]
+[[File:Schematic for ‘U’ structure.PNG|400px|thumb|center|Figure 26.Schematic for ‘U’ structure]]
-The most important target for this project is reducing the crosstalk between two patch antennas and keeping the antenna system in same plane. Comparing the dual antennas system with ‘U’ structure with antenna system without cut, the figure 24 clearly demonstrates that the coupling between two patch antennas has been reduced nearly 20dB at resonate frequency 2.4GHz no matter what simulation or measurement. The final measured result of coupling is around -45dB which is satisfied with requirement of project.
+The most important target for this project is reducing the crosstalk between two patch antennas and keeping the antenna system in same plane. Comparing the dual antennas system with ‘U’ structure with antenna system without cut, the figure 25 clearly demonstrates that the coupling between two patch antennas has been reduced nearly 20dB at resonate frequency 2.4GHz no matter what simulation or measurement. The final measured result of coupling is around -45dB which is satisfied with requirement of project.
 Actually there are a little bit errors between simulated S21 without ‘U’ structure and measured S21 without ‘U’ structure. The reason is the actual patch antennas system without ‘U’ structure was not fabricated. In order to realize this case, the project group stuck some copper slots to cover ‘U’ structure. So glue could a factor which can affect the measured results. However the errors are in a reasonable range so it is still acceptable.
-As the figure 25 shows, the letter ‘a’ and ‘b’ represent height and width of a slot. Currently the best size of slot can be obtained through HFSS when a is equal to 46mm and b is equal to 2mm.
+As the figure 26 shows, the letter ‘a’ and ‘b’ represent height and width of a slot. Currently the best size of slot can be obtained through HFSS when a is equal to 46mm and b is equal to 2mm.
 The principle of ‘U’ structure is based on an isolation technology of reverse phase coupling. Assuming the signal comes into left patch antenna. From the figure 25, the black arrow indicates the surface current direction in left antenna. Due to the interference between two antennas, this surface current in left antenna would effect on right one and cause a same direction surface current in right patch antenna. However if there is a ‘U’ structure between patch antennas, from the figure 25 the red arrows indicate the surface current flow direction in slots. It is clearly to see the current flowing in right arm is opposite direction compared with original surface current. This opposite direction surface current would cancel out the original coupling in right antenna. So that is the reason why the ‘U’ structure can be used to reduce coupling for strongly coupled antennas.

@@ Line 424: / Line 424: @@
 For the operational distance test, we made the wheel spin at a fixed speed, then we gradually moved the antennas away from the absorber until “No Connection” was displayed on the screen. Meanwhile, the distance between the antenna and absorber could be considered as the maximum operational distance.
-[[File:Measured results from tachometer and constructed system.PNG|400px|thumb|center|Table 9.Measured results from tachometer and constructed system]]
+[[File:Measured results from tachometer and constructed system.PNG|400px|thumb|center|Table 11.Measured results from tachometer and constructed system]]
-[[File:Operating distance for the constructed system.PNG|400px|thumb|center|Table 10.Operating distance for the constructed system]]
+[[File:Operating distance for the constructed system.PNG|400px|thumb|center|Table 12.Operating distance for the constructed system]]
-Table 9 shows the results measured by the tachometer and the constructed system. It is clear that the results are very close to each other with the maximum error only 3.3%, which means the system has satisfied the requirement of accuracy.
+Table 11 shows the results measured by the tachometer and the constructed system. It is clear that the results are very close to each other with the maximum error only 3.3%, which means the system has satisfied the requirement of accuracy.
-Table 10 provides the information about the operational distance. From the table, it can be concluded that the maximum distance for the system is roughly 70 cm. Given that the operating distance for the original system was 57 cm [2], the system has already been improved from the respective of the operating distance.
+Table 12 provides the information about the operational distance. From the table, it can be concluded that the maximum distance for the system is roughly 70 cm. Given that the operating distance for the original system was 57 cm [2], the system has already been improved from the respective of the operating distance.
 == Reference ==

@@ Line 284: / Line 284: @@
 From figure 6, this method is also cutting slots on ground plane between two same directional patch antennas and the ‘U’ shape is composed of three slots. The principle of the ‘U’ shape structure is based on an isolation of reverse phase coupling for reducing coupling.
-[[File:Dual patch antennas with 'U' structure.PNG|400px|thumb|center|Figure 9.Dual patch antennas with 'U' structure]]
+[[File:Dual patch antennas with 'U' structure.PNG|400px|thumb|center|Figure 14.Dual patch antennas with 'U' structure]]
 === 2. Antenna results ===
@@ Line 303: / Line 303: @@
 * The length of rectangle (y0) which should be substrate on patch
-[[File:Calculated parameters of patch antenna.PNG|400px|thumb|center|Table 4.Calculated parameters of patch antenna]]
+[[File:Calculated parameters of patch antenna.PNG|400px|thumb|center|Table 6.Calculated parameters of patch antenna]]
-[[File:Optimal result for parameters.PNG|400px|thumb|center|Table 5.Optimal result for parameters]]
+[[File:Optimal result for parameters.PNG|400px|thumb|center|Table 7.Optimal result for parameters]]
@@ Line 316: / Line 316: @@
 The Figure below illustrates the reflection coefficient at resonate frequency 2.4GHz. The S11 is around -23.78dB at resonance frequency 2.4GHz, which means nearly 99.3% energy has been transmitted through the patch antenna. The reflection coefficient is lower and the input impedance match the transmission line. So the input impedance is close to 50 ohms.
-[[File:Reflection coefficient for single patch antenna.PNG|400px|thumb|center|Figure 10.Reflection coefficient for single patch antenna ]]
+[[File:Reflection coefficient for single patch antenna.PNG|400px|thumb|center|Figure 15.Reflection coefficient for single patch antenna ]]
 * Dual patch antennas (Without ‘U’ structure):
@@ Line 332: / Line 332: @@
-[[File:Measured reflection coefficient for dual patch antennas.PNG|400px|thumb|center|Figure 12.Measured reflection coefficient for dual patch antennas]]
+[[File:Measured reflection coefficient for dual patch antennas.PNG|400px|thumb|center|Figure 16.Measured reflection coefficient for dual patch antennas]]
-[[File:Measured coupling effect for dual patch antennas.PNG|400px|thumb|center|Figure 13.Measured coupling effect for dual patch antennas ]]
+[[File:Measured coupling effect for dual patch antennas.PNG|400px|thumb|center|Figure 17.Measured coupling effect for dual patch antennas ]]
 ''Comparison:''
@@ Line 346: / Line 346: @@
 The figure 16 and figure 17 illustrate prototype of dual patch antennas with ‘U’ structure
-[[File:Simulated results with measured results.PNG|400px|thumb|center|Figure 14.Simulated results with measured results]]
+[[File:Simulated results with measured results.PNG|400px|thumb|center|Figure 18.Simulated results with measured results]]
-[[File:Top view of dual antennas.png|400px|thumb|center|Figure 15.Top view of dual antennas]]
+[[File:Top view of dual antennas.png|400px|thumb|center|Figure 19.Top view of dual antennas]]
-[[File:Bottom view of dual antennas.png|400px|thumb|center|Figure 16.Bottom view of dual antennas]]
+[[File:Bottom view of dual antennas.png|400px|thumb|center|Figure 20.Bottom view of dual antennas]]
 ''Comparison:''
@@ Line 357: / Line 357: @@
 For the crosstalk efficient, the crosstalk efficient of simulated at resonate frequency is around -43.3dB and the measured crosstalk efficient is -45dB at 2.4GHz. Those two result are close to each other and it is obviously that the coupling between two patch antennas has been reduced dramatically compared with the without ‘U’ structure case. Also from the figure 15, the simulated curve of reflection coefficient overlap the measured one and crosstalk curve of simulated and measured are also similar with each one. The performance of dual patch antennas has met the requirement. The details of principle of ‘U’ will be discussed in next section.
-[[File:Radiation Pattern for dual antennas in E-plane.PNG|400px|thumb|center|Figure 17.Radiation Pattern for dual antennas in E-plane]]
+[[File:Radiation Pattern for dual antennas in E-plane.PNG|400px|thumb|center|Figure 21.Radiation Pattern for dual antennas in E-plane]]
-[[File:Radiation Pattern for dual antennas in H-plane.PNG|400px|thumb|center|Figure 18.Radiation Pattern for dual antennas in H-plane]]
+[[File:Radiation Pattern for dual antennas in H-plane.PNG|400px|thumb|center|Figure 22.Radiation Pattern for dual antennas in H-plane]]
-[[File:Radiation Pattern for dual antennas.PNG|400px|thumb|center|Figure 19.Radiation Pattern for dual antennas]]
+[[File:Radiation Pattern for dual antennas.PNG|400px|thumb|center|Figure 23.Radiation Pattern for dual antennas]]
-From figure 17 to figure 19, they demonstrate measured radiation pattern for two patch antennas with ‘U’ structure. All the radiation patterns were measured in the echoic chamber. The two patch antennas system was measured from -180 degree to 180 degree and the measured frequency at 2.4GHz with 1601 sweep points. From the figure 20, it is obviously that the maximum gain in E-plane and H-plane are at 0 degree. So the performance is acceptable and this design has satisfied with the requirement of the project.
+From figure 21 to figure 23, they demonstrate measured radiation pattern for two patch antennas with ‘U’ structure. All the radiation patterns were measured in the echoic chamber. The two patch antennas system was measured from -180 degree to 180 degree and the measured frequency at 2.4GHz with 1601 sweep points. From the figure 23, it is obviously that the maximum gain in E-plane and H-plane are at 0 degree. So the performance is acceptable and this design has satisfied with the requirement of the project.
 ''Results summary:''
@@ Line 370: / Line 370: @@
 '''Single patch antenna:'''
-[[File:Simulated and measured result for single patch antenna.PNG|400px|thumb|center|Table 6.Simulated and measured result for single patch antenna]]
+[[File:Simulated and measured result for single patch antenna.PNG|400px|thumb|center|Table 8.Simulated and measured result for single patch antenna]]
 '''Dual patch antennas without ‘U’ structure:'''
-[[File:Simulated and measured results for dual patch antennas without 'U'.PNG|400px|thumb|center|Table 7.Simulated and measured results for dual patch antennas without 'U']]
+[[File:Simulated and measured results for dual patch antennas without 'U'.PNG|400px|thumb|center|Table 9.Simulated and measured results for dual patch antennas without 'U']]
 '''Dual patch antennas with ‘U’ structure:'''
-[[File:Simulated and measured results for dual patch antennas with 'U'.PNG|400px|thumb|center|Table 8.Simulated and measured results for dual patch antennas with 'U']]
+[[File:Simulated and measured results for dual patch antennas with 'U'.PNG|400px|thumb|center|Table 10.Simulated and measured results for dual patch antennas with 'U']]
@@ Line 386: / Line 386: @@
 This section will focus on some physical explanations about the ‘U’ structure and explain the reason why the ‘U’ structure can reduce the coupling between two patch antennas.
-[[File:Simulated and Measured S21 for dual antennas in different conditions.PNG|400px|thumb|center|Figure 20.File:Simulated and Measured S21 for dual antennas in different conditions]]
+[[File:Simulated and Measured S21 for dual antennas in different conditions.PNG|400px|thumb|center|Figure 24.File:Simulated and Measured S21 for dual antennas in different conditions]]
-[[File:Schematic for ‘U’ structure.PNG|400px|thumb|center|Figure 21.Schematic for ‘U’ structure]]
+[[File:Schematic for ‘U’ structure.PNG|400px|thumb|center|Figure 25.Schematic for ‘U’ structure]]
-The most important target for this project is reducing the crosstalk between two patch antennas and keeping the antenna system in same plane. Comparing the dual antennas system with ‘U’ structure with antenna system without cut, the figure 21 clearly demonstrates that the coupling between two patch antennas has been reduced nearly 20dB at resonate frequency 2.4GHz no matter what simulation or measurement. The final measured result of coupling is around -45dB which is satisfied with requirement of project.
+The most important target for this project is reducing the crosstalk between two patch antennas and keeping the antenna system in same plane. Comparing the dual antennas system with ‘U’ structure with antenna system without cut, the figure 24 clearly demonstrates that the coupling between two patch antennas has been reduced nearly 20dB at resonate frequency 2.4GHz no matter what simulation or measurement. The final measured result of coupling is around -45dB which is satisfied with requirement of project.
 Actually there are a little bit errors between simulated S21 without ‘U’ structure and measured S21 without ‘U’ structure. The reason is the actual patch antennas system without ‘U’ structure was not fabricated. In order to realize this case, the project group stuck some copper slots to cover ‘U’ structure. So glue could a factor which can affect the measured results. However the errors are in a reasonable range so it is still acceptable.
-As the figure 22 shows, the letter ‘a’ and ‘b’ represent height and width of a slot. Currently the best size of slot can be obtained through HFSS when a is equal to 46mm and b is equal to 2mm.
+As the figure 25 shows, the letter ‘a’ and ‘b’ represent height and width of a slot. Currently the best size of slot can be obtained through HFSS when a is equal to 46mm and b is equal to 2mm.
-The principle of ‘U’ structure is based on an isolation technology of reverse phase coupling. Assuming the signal comes into left patch antenna. From the figure 22, the black arrow indicates the surface current direction in left antenna. Due to the interference between two antennas, this surface current in left antenna would effect on right one and cause a same direction surface current in right patch antenna. However if there is a ‘U’ structure between patch antennas, from the figure 22 the red arrows indicate the surface current flow direction in slots. It is clearly to see the current flowing in right arm is opposite direction compared with original surface current. This opposite direction surface current would cancel out the original coupling in right antenna. So that is the reason why the ‘U’ structure can be used to reduce coupling for strongly coupled antennas.
+The principle of ‘U’ structure is based on an isolation technology of reverse phase coupling. Assuming the signal comes into left patch antenna. From the figure 25, the black arrow indicates the surface current direction in left antenna. Due to the interference between two antennas, this surface current in left antenna would effect on right one and cause a same direction surface current in right patch antenna. However if there is a ‘U’ structure between patch antennas, from the figure 25 the red arrows indicate the surface current flow direction in slots. It is clearly to see the current flowing in right arm is opposite direction compared with original surface current. This opposite direction surface current would cancel out the original coupling in right antenna. So that is the reason why the ‘U’ structure can be used to reduce coupling for strongly coupled antennas.
 == Software Design ==

@@ Line 254: / Line 254: @@
 [[File:Summary for simulation and measurement.PNG|400px|thumb|center|Table 5.Summary for simulation and measurement ]]
-Figure 13 shows the simulated S11 with RF behaviour considered and all results are summarised in Table 4. We can clearly see that resonant frequencies for the simulation and measurement are very close to each other, which means the resistor could be the potential reason which causes the resonant frequency shift.
+Figure 13 shows the simulated S11 with RF behaviour considered and all results are summarised in Table 5. We can clearly see that resonant frequencies for the simulation and measurement are very close to each other, which means the resistor could be the potential reason which causes the resonant frequency shift.
 == Antenna Design ==

← Older revision		Revision as of 10:42, 22 October 2015
Line 252:		Line 252:


−	[[File:Summary for simulation and measurement.PNG\|400px\|thumb\|center\|Table 5.Summary for simulation and measurement ]]	+	[[File:Summary for simulation and measurement.PNG\|400px\|thumb\|center\|Table 5.Summary for simulation and measurement ]]

	Figure 13 shows the simulated S11 with RF behaviour considered and all results are summarised in Table 4. We can clearly see that resonant frequencies for the simulation and measurement are very close to each other, which means the resistor could be the potential reason which causes the resonant frequency shift.		Figure 13 shows the simulated S11 with RF behaviour considered and all results are summarised in Table 4. We can clearly see that resonant frequencies for the simulation and measurement are very close to each other, which means the resistor could be the potential reason which causes the resonant frequency shift.