wilkinson lower impedance version

[rf_engineer_5]

A question - are designs of wilkinson power combiners/dividers common with impedances less than 50ohms?

Trying to find if 50ohms/12.5ohms is feasible for freqs less than 25MHz. I am just not seeing much literature for this type of design that have built in impedance transformations.

thanks

 

[FvM]

Transmission line based RF components, e.g. Wilkinson divider are not very practical in low MHz range due to need of very long cables. Transformers, also transmission line transformers, are better suited.

 

[psach27]

Hi,

You can design Wilkinson divider at smaller frequencies and differents Z0, using two transmission lines of lambda/4 length and impedance sqrt(2)*Z0, and a resistance of 2*Z0, as is shown below:

But as @FvM said , that is very unpractical. Imagine make it with coaxial cables of PTFE. At 25MHz, Lambda/4 is 8.2 meters, a lot of length for the two branches.

Maybe using discrete components is more feasible, taking into account that a lambda/4 transmission line can be made by three components: a coil and two capacitors:

Also, it is important to take into cosiderantion the power ratings of this components.

Regards

 

[rf_engineer_5]

Thanks for the replies. I do understand the problems of implementation at lower freqs but mainly I was just looking for architecture help for impedance transformation within a wilkinson. From all of the text books I have and other resources found online, the vast majority of wilkinsons are 50ohms in/out. I think that maybe the solution here is providing either external matching networks or transformers to get what is wanted.

 

[D.A.(Tony)Stewart]

The purpose of your query could be asked instead with the desired effect or "specs".

 

[vfone]

An LC Wilkinson splitter can go down to about 1MHz:

LC Wilkinson Splitter-Combiner Designer

Radio Frequency Engineering Calculator.

leleivre.com

 

[D.A.(Tony)Stewart]

An LC Wilkinson splitter can go down to about 1MHz:

LC Wilkinson Splitter-Combiner Designer

Radio Frequency Engineering Calculator.

leleivre.com

Yes. You can do it for any frequency until ESR of parts affects the results Simulation