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synthesis of microwave diplexers

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cliffliu

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diplexer design

For microwave diplexer design.
Have anyone know paper or software can download it?
Waveguide or microstrip line,all good.

THX!
 

filterman

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diplexer design +download

There are tens of papers on this subject, maybe more. For various applications and technologies or specification. Your post too general.
Any way you could pick the Index of The Transaction of IEEE-MTT and you will find many references, there are books with whole chapters on this subject.(MYJ aERTECH hOUSE, Ian Hunter-Theory and Design of Microwave Filters.
There are examples of diplexer design that come with "serenede 8.71", also with "Eagleware". There is a wealth of information on this subject.
 

PeterMartin

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A simple tip would be to look at the reflected group delay of the common junction and use that as a template for getting the correct structure in practice.
 

PeterMartin

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A simple tip would be to look at the reflected group delay of the common junction and use that as a template for getting the correct structure in practice.

This application Note and Associated Files may be useful

http://www.rfshop.co.uk/DiplexerAppNote.doc
http://www.rfshop.co.uk/DiplexerAppNoteFiles.zip

Incidentally I don't think that Ian Hunter says much, if anything, about Diplexers and Multiplexers in his book "Theory and Design of Microwave Filters".[/url]
 

cmarianodiaz

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Dear expert:
I read about diplexer application note and I had certain questions:

1) in the equivalent circuit (MWO) found in the zip file, note that in the optimization process ; this included the resonance frequency of each resonator .
if we are talking about of allpole filters or synchronously tuned, I do not understand because it varies the resonant frequency of each resonator to optimize the diplexer?.
On the other hand, in the general matrix coupling only non-zero values of the diagonal occur when we are present of filter asynchronously tuned.

2) in the common junction of diplexer , you use an extra rod for coupling the two filters;
how I can adapt the two filters by the group delay if I use a T junction wire?
(please teach me with an illustrative example)
thanks in advance

regards from argentina.
 

PeterMartin

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Yes the resonant frequency of adjacent resonators is perturbed slightly by the presence of the joint port or common junction.

In practice, this is not a noticeable problem, it just means a slight adjustment of a tuning screw.

You can make the common junction any way you like and the same method of using the reflected group delay as a 'template' for its design will apply.
 

cmarianodiaz

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thank you very much for your help.
I am currently in the process of sizing the diplexer (PCS1900), it consists of two bandpass filters with 4-pole cuadruplets topology;therefore is a symmetric filter.
Please; I'd like to clarify me some doubts:

1) I have used Ansoft HFSS to determine the dimensions of the cavity. dimensions are:
-height of cavity: 30mm
-square cavity have a side length 35mm
-resonator length: 25mm(resonator length between 50 and 80 percent of a quarter wavelength. (Macchiarella paper)
-resonator diameter:10mm


The problem I have is that between 1880 (RX f0) and 1960 (Tx f0), there is little variation in the tuning screw (approx 2-3 mm), as I can do to increase the range of variation (taking into account that use the same dimensions of cavity and the same length of the resonator for the two bands)?

2) in the process of optimization of the diplexer the frequencies of the resonators varied slightly. the question is:
to determine the dimensions of the coupling in the hfss soft (eigenmode solver), what formula should be used?
k = re (mode2) ^ 2-re (MODE1) ^ 2/re (mode2) ^ 2 + re (MODE1) ^ 2 ??????
should use this formula? . Or the k formula of asynchronous filter

many thanks
 

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