How to design a directional coupler with Lumped LC net works

http://www.odyseus.nildram.co.uk/RFM...les/Hybrid.pdf

http://michaelgellis.tripod.com/direct.html

To prevent signal reflection from antenna? Wouldn't you rather need an isolator?
Mosieur_Oiso

isolator
OK
How to design it with lumped LC networks?

Hi there,
Yes, that is possible, but not using LC SMD components. You will need a ferrite disk and you will have to wind 3 coils around it at 120 degree angle (see the article there is a nice picture of it...)
Depending on your application and frequency, you might better get one from a component manufacturer, I happened to use miniature isolators from TDK (but this is just one example), you can find different models on their website: http://www.tdk.co.jp/tefe02/rf_network.htm#aname5
You can request some samples through one on their sales offices, but usually this doesn�t go very fast
Good luck!
Mosieur_Oiso

You can refer to the Chapter 12 of the "Lumped element for RF and Microwaves circuit" by Inder Bahl.(Page No364-366). calculation of L & C value is giventher.