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confuse about feeding structure

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sensen9966

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i don't know how to exactly express my question and confuse. please see bellow.

what's the basic concept of using a feeding line or network?

what's the main and real work done by feeding line or network?

how to choose a right feeding structure to feed a resonator?


i just know through the feed line the RF energy push into the system. and feeding in different position may excited some different RF mode.

but i also no detailed concept of how to choose a feeding structure.

for example a λ/4 step impedance resonator, how to feed this resonator right? and for arbitrary shaped structure, is there some basic rule or guide to choose a suitable feeding structure?

i have used google but didn't find the right result of what i want. just found many papers and within their design, some kinds of feeding structure is used, but they didn't explain more about why that feeding structure used there.

please help, any guide or some references etc. Any thing figure it out will useful to me. i just want to make this confuse clear.

thanks in advance.
 

Feeding line feeds RF or microwave energy from source into load. Usually it is one of transmission lines e.g. microstrip or coplanar wave guide. What kind is better depends on your application and budget. This line must be matched with source and load, sometimes special matching networks are used for this purpose. When you are feeding resonator more requirements should be met than for broadband load. You need to have right coupling in order to get right resonators parameters. You also need to excite right mode into resonators or waveguides. All these questions are answering during design process, there may be different solutions and you need to find the best one for your particular case. I think you need to chose resonator first and then find the best feeding line for it.
 

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    sensen9966

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RF-OM said:
Feeding line feeds RF or microwave energy from source into load. Usually it is one of transmission lines e.g. microstrip or coplanar wave guide. What kind is better depends on your application and budget. This line must be matched with source and load, sometimes special matching networks are used for this purpose. When you are feeding resonator more requirements should be met than for broadband load. You need to have right coupling in order to get right resonators parameters. You also need to excite right mode into resonators or waveguides. All these questions are answering during design process, there may be different solutions and you need to find the best one for your particular case. I think you need to chose resonator first and then find the best feeding line for it.
Click to expand...

RF-OM, thanks for you respond.

so is there some reference for this topic? i want to find some rule to help figure something out.
i want to excited some SIR structure another case is a coupled line, for SIR case, SIR also has some coupling with other structure. for coupled line case, both edge and end coupled there. to reach the best performance what i should do. so i want to know a little more about the simple rule for design or choosing the feeding structure.

also from the simulation view. what simple simulation method is useful for finding out the best feeding structure.

maybe some references or comparison will do better explain for me. as you experience. could you advise some good references with the good feeding.

thanks again.
 

I do not think there may be one reference. Every design is different and each time you need to find the best solution and it is not always the best technically because economics demands its own considerations. It may be big difference depends on where do you use your SIR in filter, in antenna or somewhere else; how many of resonators are used and what is the coupling. Good solution may be found only as results of thorough analyzes of all the requirements and possibilities and seeing the whole project. I used SIR a few times for filters and always feed it with microstrip lines and feeding point was in the middle of resonator, so the structure was symmetrical. Now I am considering it for antenna, but so far it is just an idea, no design done yet. For the references you can use well known books from David Pozar, Brian Wadell’s Transmission line Handbook (but be careful: there are a lot of typos). On this site there are a lot of topics about references for microwave design books, please check them by search. For me it is not so easy to give you references because I usually use kind of unusual way to find information. For many years I developed thousands of detailed worksheets and they help me a lot. When I need to find more information I use my electronic library (it is really huge) and do the search by keywords. Then print those pages that related to my project and put them into special folder. This is proven method but as result I do not remember the exact titles and authors names for all these books. The only drawback is search time that sometimes may be as long as 20 or 24 hours, then it may take a few hours to print and sort related pages. This allows to have good and easily accessible information for the duration of current project.
 

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    sensen9966

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RF-OM, thanks for your kindness reply and guide.
really helpful.
 

RF-OM said:
I do not think there may be one reference. Every design is different and each time you need to find the best solution and it is not always the best technically because economics demands its own considerations. It may be big difference depends on where do you use your SIR in filter, in antenna or somewhere else; how many of resonators are used and what is the coupling. Good solution may be found only as results of thorough analyzes of all the requirements and possibilities and seeing the whole project. I used SIR a few times for filters and always feed it with microstrip lines and feeding point was in the middle of resonator, so the structure was symmetrical. Now I am considering it for antenna, but so far it is just an idea, no design done yet. For the references you can use well known books from David Pozar, Brian Wadell’s Transmission line Handbook (but be careful: there are a lot of typos). On this site there are a lot of topics about references for microwave design books, please check them by search. For me it is not so easy to give you references because I usually use kind of unusual way to find information. For many years I developed thousands of detailed worksheets and they help me a lot. When I need to find more information I use my electronic library (it is really huge) and do the search by keywords. Then print those pages that related to my project and put them into special folder. This is proven method but as result I do not remember the exact titles and authors names for all these books. The only drawback is search time that sometimes may be as long as 20 or 24 hours, then it may take a few hours to print and sort related pages. This allows to have good and easily accessible information for the duration of current project.
Click to expand...


hi i am designingMEMS resonator how can i calculate the feed length and width actually i am using microstrip to coplanar transition
29_1253007385.gif
 

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