The progress in week 5

Fifth Lab Day

Details for 5th weeks's activities:

1. The first target of this week is to complete the "Power Divider Calculator" interface, which may focus on the calculation of 2-way power divider. The calculation of input reflection for a Wikinson power divider is more easier than that in four way divider, which can be seen as below:
   
   It is easy to find out that the input reflection graph will not change as the change of Φx,because there are no connection lines existing. After editing this equation with original calculation codes, which are shown below:
   
   The interface can be used to calculate input reflection for either 2-way or 4-way power divider as customer preferred. We have tested it for several times and the final outcome of the interface is shown below:
   
   
   
   
   Customer can choose 2 way or 4 way power divider, the graph of input reflection can be shown after inputting the value of fundamental frequency and connection transmission lines' length. Then user can apply it to their own design by referring the structure of 2-way or 4-way divider that we have provided as below:$$$$$$. Up to now, our group has nearly complete the whole design work of the automatic design of power divider. We will prepare for the bench and presentation of week 6.
2. The second thing we did is to complete the uploading work of blog information, which will provide the basic introduction of our project to the department of Electrical Engineering and Electronics (EEE), we have chose a graph to represent our group project works, which has been attach as below:
   
   After that, I have designed and generated a QR code which links with the home page of my blog. The QR code is shown below:
   
   We will attach this code on our project poster, then any people who are interest in our project can visit the blog via scanning the code in a short time. 
3. The third task of this week is to crate our project poster, which will be used in the bench on Friday next week. The poster has an significant role during the bench, which can attract people's attention at the first time. People can have a basic understanding with the automatic design of power divider by seen the content of poster.  The content of our poster should be succinct and directly in order to attract people's eyes, then a series of graph will be shown in this poster with the same order of our experiment process. For the lab day 5, we have complete a primary structure with simple outlook,   then we will modify and complete it at later fewer days, trying our best to make it more academic and attractive, the final results of the poster will be update at here before next Friday.

Summary of 5th week's activities:

• Complete the 2-way power divider input reflection calculation for corresponding matlab interface
• Complete the uploading work for the project blog as EEE department required.
• Planning and complete the primary outlook of project poster. 

The progress in week 4

Fourth Lab Day

Details for 4th weeks's activities:

1. The first target of this week is to modifying the code of 'power divider calculator' interface. Our group has checked the input reflection calculated formulas with our supervisor based on corresponding codes, the error was finally founded and the interface performs correctly after the modification. The upgraded codes for the calculation of input reflection parts are shown below :
   
   The codes that has been modified are lighting on as the figure shown. After the debugging of codes,  we have tested the function of  power divider calculator with several groups of data. According to the experimental results, it shows that the calculator interface can be used to obtain correct graph of input reflection with different fundamental frequency and transmission lines' length for a four way power divider.  The tested results are shown below in series:

   

   Input reflection of 4 way power divider (Φx=0)

   

   Input reflection of 4 way power divider (Φx=π/2)

   

   Input reflection of 4 way power divider (Φx=π)

   

   Input reflection of 4 way power divider (Φx=3π/2)

   

   Input reflection of 4 way power divider (Φx=5π/2)

   It can be proved that all of this results are correct when compared with the theoretical graphs which have mentioned at week 2.  However, the power divider calculator that we designed is only applied for 4 way power divider. According to background knowledge, it has indicated that the calculation of input reflection for multiple ways power divider will be more complex as the grown of output amounts. Based on the limit of experiment period, our group decide only to complete this interface for 2-way and 4-way power divider. The work of 2-way power divider will be conducted at week 5. The second task for this week is to develop another interface which relative to the design of unequal power divider.
2. We have a group meeting that learned and discussed the knowledge of unequal power divider, which mainly focus on the fundamental field of 2-way unequal power divider. The model of 2 way unequal power divider with five different components are shown below:
   
   According to the figure above, it can be seen that the structure of 2 way unequal power divider is similar with equal power divider. However, the value of each component will be different in order to achieving different purpose of the unequal power divider, in details, it mostly depend on what value of power split ratio (Pa/Pb) customer want. The corresponding calculation for each component are listed below, which can be used for the coding of interface of unequal power divider:
   
   Based on the fundamental learning of unequal power divider,  we decided to coding a interface of unequal power divider which can be used for any customer who want to design an unequal power divider. With the help of this interface, company do not needs to understand the detailed knowledge of the calculation for unequal power divider. The only thing they need to do is inputting the value of power split ratio, then the interface can calculate all designed value for each component automatic.
3. The detailed processes that to complete the unequal power divider designer including three stages. First of all, we crated a simply 'matlab' function codes that used to calculated each component's value based on the given formulas. The codes are shown below:
   
   
   The codes that are light on is the linking component between the codes of interface and and calculated function codes. It is also the most difficult part for the coding of this interface is how to linking the outputs of calculated function with the static text at interface. In simply words, the hardest working is how to make the interface outputs display correct results. Thirdly, the interface named "unequal power divider designer" was generated by simulating corresponding codes. There are two inputs with five outputs in the interface, user can edit the designed value of input impedance for power divider and the value of power split ratio, the corresponding designed value of each component will be displayed in the output respectively followed by click the push button 'calculate'. We have tested the interface for two groups of data, the results are indicted correct and are shown below: 

   

   power divider with power split ratio equals 1

   
   

   

   power divider with power split ratio equals 2

4. The project named automatic design of power divider has nearly completed two calculation interface before week 5.  Our group will complete their performance respective at nest week, meanwhile, we will have a conclusion for this project based on varies of parts. 

Summary of 4th week's activities:

• Completing the debugging of the power divider calculator interface, modifies its calculation for a four way Wikinson power divider.
• Learning the knowledge of unequal power divider and discussion the interface of unequal power divider designer for a 2 way Wikinson power divider 
• Designed and completed the interface of unequal power divider by using Matlab "GUI" function. 

The progress in week 3

Third Lab Day

Details for 3rd weeks's activities:

1. We have a group meeting firstly, discussing the content referred to the writing of sustainable design. The whole name of this paper is sustainable development (SD) and ethical aspects of the design, which are divided into four parts: a basic description of our project; the regulatory considerations of actual power divider ("RoHS", "WEEE"); SD/Ethical implications of large scale manufacture and sale; SD/Ethical implications of follow-on products or markets. We will complete this paper before 17th Feb,2014. 
2. Review the inner operation of a four-way power divider which main focus on the part of input reflection. The detailed knowledge of this field can be seen at the log of week 2. The basic equation that used to calculated the input reflection of a four-way power divider can are shown below:
   
   where the calculation of "Sre" and "Sim" are represent as:
   
   
3. According to the equations which show above, we began to use "Matlab" software to coding a function that aimed to calculating the input reflection of a four way power divider, where the value of fundamental frequency (fo) and transmission lines`s length (x) can be setting before each calculation.The detailed code for this part is shown below:
   
   It can be seen from the code that only the "x" and "fo" are independent variables, where the scale of frequency is multiple by [0.4,1.6]. This code can be used as a component of the final interface named "power divider calculator", which is our next target of this project. We used this code to calculating the graph of input reflection for a four way power divider with "x=π" and "x=π/2", the results are shown below:
   
   
   Compared with the simulation results which obtained at week 2, we can figure out that there are existing some error with out calculation because the graph of "x=π/2" is wrong. Meanwhile, there are existing some strange points which can be easier found by change the results from 2D to 3D, eg.fo=1GHz, x=2*pi/2.
   
   We have checked our edited equations and relative paper, no error was founded and our supervisor will check it in later few days. Although there are some error in the calculation of input reflection, it will not influences our next research stage. 
4. Our group began to developing the interface of "power divider calculator" by using the software "Matlab". The operation interface is shown below:
   
   We have built a graphical user interface (GUI) to design our "power divider calculator", there are three input options: number of output;fundamental frequency in GHz and transmission line's length in degree. The graph of input reflection will be shown at the right after input parameters and push "calculate" button. The codes of the GUI are shown below:
   
   The codes which are lighting on are used to linking our previous calculation codes with the GUI. Thus the interface can calculate the results by calling the calculation codes. 
5. After completing the design of "power divider calculator" interface, we began to debugging by several times of calculation. The results show that the codes for the GUI is successful while the calculation results still existing error just like I mentioned previous. We will try to figure out the reason in later days and then modify the original calculation codes. Hence a calculation results will be shown below with "fo=1 GHz" and "x=0 in degree":
   
   It can be found that value of "Number of output" is in blank, the reason is that we just focus on the four way power divider for this week so the default value for outputs number is 4. We will improve this function at next week, aiming at customer can calculate the input reflection for multiple inputs as they want. 

The progress in week 2

Second Lab Day

Details for 2nd weeks's activities:

1. For the second week our group are most focus on the knowledge learning of four way power divider, which constructed by cascading two basic two way power divider. According to previous relative research, it shows that the length of interconnection transmission lines can affect the properties of 4-way divider. We decided to build and simulate a 4-way Wilkinson power divider by using AWR, obtaining its input reflection, transmission, output reflection and isolation curves corresponding to different value of transmission lines' length. 
2. We have a group meeting with our supervisor Dr.Zhou on 7th Feb, 2014. Because of the knowledge absence for RF circuit field, Dr. Zhou have introduced the basic concept referred input and output reflection for a divider, as well as transmission, isolation and 'ABCD' matrix . Hence we are more concentrating on the calculation and results of input reflection, in order to knowing how to boarder or narrower the usable bandwidth by changing the length of transmission lines. The calculation of input reflection for a four way power divider with normalized frequency f'=f/fo (0<f'<2) is shown below,
   
   hence Φx represent the length of transmission lines and we only choose nπ/2 to ensuring the symmetry of response.
3. After meeting, we began to construct a basic four way Wilkinson power divider by using Microwave office software. Based on the outcome at week 1, the four way power divider is constructed by cascading two 2-way divider to another one. The designed circuit is shown below:
   
    The component that represent the length of transmission lines are shown in the circuit graph above, the length is presented in degree and hence the value is 90 degree.
4. Our group began to simulating the four way power divider and tried to obtaining its input reflection. It is complex and difficult to obtaining a series of ideal input reflection graphs for different value of transmission lines' length (Φx). It costed a long time to finding a suitable range of actual frequency, in order to getting a perfect input reflection graphs corresponding to varies Φx.Followed by setting the input reflection in S11 with unit dB and simulated the input reflection curves under five value of Φx in turns (0, π/2, π, 3π/2, 5π/2). The results is shown below respectively:

   

   Transmission lines' length is 0 in degree

   

   Transmission lines' length is 90 in degree

   

   Transmission lines' length is 180 in degree

   

   Transmission lines' length is 270 in degree

   

   Transmission lines' length is 450 in degree
5. Then we tried to combining these input reflection curves by superposition and analysis the effect of transmission lines on four way power divider. The graph is shown below:
   
   
   In normally, the usable bandwidth of the standard Wilkinson power divider means the frequency range that corresponding value of input reflections are better that -20 dB. It can be found that the usable bandwidth is boarder as the increase of Φx in order. Our simulation results have shown that the bandwidth of a 4-way power divider can be significantly boarder by choosing suitable length of transmission lines. 
6. At last, we tried to getting the graph of transmission, output reflection and isolation of the 4-way power divider with Φx equal to 5π/2. The results is shown below:
   
   
   While there are existing some error when compared with the ideally graph, the curve of S22 and S23 are wrong and the reason may due to this results are simulated under a theoretical situation. Our group will obtained a measured graph in later few days and then compare it to the ideally one again.

Summary of 2nd week's activities:

• Learning the effect of interconnection transmission lines on four-way Wilkinson power divider
• Using Microwave Office software to built a four-way power divider
• According to the simulation of the four-way power divider, obtained the input reflection graphs corresponding to different value of transmission lines' length.