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What kind of ferrite to use for RF choke (5-900MHz and 12A)?

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Bouli

Bouli

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Hi

I need to make RF choke for 5-900MHz for high current about 12A. My question is: what kind of ferrite should I use. Maybe someone of you has a good paper about making RF chokes?
 

rf choke

This is a very wide frequency range. You would be better off having several inductors in series of different values. For the higher frequency end (lowest inductor values) use air core coils.
 

making rf chock

your problem seem difficult to solve. Very large BW and strong current.
I agree flatulent, usually the way is place a series of scaled inductors.

Since i think for highr inductance coil, a ferromagnetic core should be used, also the saturation should be taken in account.
Rather than an academic paper, i suggest to look at datasheets of power ferrites like Coilcraft© or Micrometals© and/or factories that produce components for RF broadcasting.

To reduce the risk of saturation, be aware to parallel connection of two or more inductors. It don't woks in practice! Only a proper, high power ferrite may be used.
 

bias tee rf choke

The standard way to keep the core from saturating is to use two coils on the same ferrite. One coil handles the 12 A, and the other coil handles the -12A return current. The net DC current exciting the ferrite is 0A.


A common example is those AC line filters that you see the power cord plugging into on the back of most pieces of test equipment.
 

how to choose rf choke

I have seen two diferent ways of solving this problem. One is to make a few inductors on the same ferrite core, but one inductor is clock wise, next one counter clock wise. I thing that because of saturations of ferrite core. There are also resistors between this coils, to minimize resonance peaks.
Another one look like one inductor, but once turns are close to each other, then are separately. There is also resistor around the few firs turns.
As I can undertand why it looks like it looks, I copletly dont know how to choose the ferrite core to this.
 

Re: RF choke

Picosecond pulse labs has a model 5589 bias tee that rejects 300 MHz to 2.8 GHz at 7A with only a 51 nH series inductor and some capacitance. Figure out how they do that, then add a bigger inductor in series for the low frequency end.

**broken link removed**
 

Re: RF choke

I can't download anything from this site. Could you paste this paper here.
 

Re: RF choke

Link and attached PDF file above give the same PDF file result in elkimhoc's post.
g579
 

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