Rf choke how does it work

The value of a choke is usually in Henrys, which is an SI unit. The Whippersnapper's Crystal Radio project does not need a choke; however, I am including it for future experimentation. One of the most common problems with using a choke is that its magnetic field often interacts with that of the coil on the ferrite rod.

This interaction can cause a feedback within the circuit. However, if you mount the choke vertically, whilst the ferrite rod is horizontal, then the interaction is minimised, but sometimes even that will not work if the two are close together.

One of my whippersnappers discovered that if you used a cylindrical shaped ferrite core and wound a coil around it, instead of through it, the interaction is further minimised. So the choke can be used to block the outside current radiation when a balance dipole is connected with a cable which is actually unbalanced. If this is correct, how can we make a choke balun in the measurement, a quarter wavelength tranmission line?

Thank you very much. Last edited: Sep 27, Hello, Below an example of a flat strip dipole is given with balun function:. Thanks for the example.

I guess I still have a lot to learn for balun. Similar threads T. Started by Tan Nov 22, Replies: 0. RF, Microwave, Antennas and Optics.

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Sign In. Login Login to everything RF to download datasheets, white papers and more content. Is this something you would do for all antennas fed by coax? If not, what are some situations that you would use it for? The only time I have found it neccessary was with a ground mounted vertical to keep the coax from acting like a radial. Then again I know some guys that have a coil in every feedline they have.

Bottom line is, it won't hurt anything to put one in, but it may help. Your form can be a coffee can or piece of PVC, anything round and the proper size will do.

N4RMT , Dec 15, Use whatever size fits the cable snugly, and use 8 or 10 of them. Put the choke at the antenna end of the feedline near the feedpoint.