bazooka choke
I am trying to design and build a PRINTED monopole antenna with no ground plane (make it a sleeve antenna). How would you make a PRINTED sleeve choke? I am making the transmission line a strip line, but it seems that just adding two lines quarter wavelength long to act as spurs is not enough.
any tips or ideas?
Thanks1
Ori
Design a printed meander line and this will be your printed choke.
http://ma.icu.ac.kr/papers/2002_MOTL_meander.pdf
Thank you Vfone for your reply.
Unfortunately, this type of solution will not solve my problem, since my antenna is NOT mounted on a ground plane. Maybe I can describe what I am looking for as a way to implement a bazooka choke in a printed manner on a printed, rubber-duck like , monopole antenna.
Thanks again,
Ori
you say there is not ground plane. But that is an impossibility. For current to go into the antenna, there has to be an equal and opposite direction current going back towards the source. In something like a coax line, this is more obvious--the forward traveling current can be thought of traveling on the center conductor, and there return current can be thought of traveling on the outer conductor shield. In this sorts of a feed, for a monopole, you might not want current flowing back on the outside of the ground shield, but instead want 100% of it flowing back on the inside of the coax ground shield. So, some put a transmission line sleave on the outer coax ground shield to stop the outside currents from flowing.
You seem to have a different feed mechanism, but still want to use a choke to do "something". Not sure what you want to do, but obviously a better description is needed.
You are right Biff, there has to be some current return path, which is on a coax, hopefully, the inner side of the outer coax shield. I didn't say there is no ground just there is no ground plane. I am indeed looking for some PRINTED (PCB) implementation of how to generate the choke in a coaxial like way.
If there is the coax just put metal tube over it and adjust the length. This is the classic Bazooka sleeve. Or use the copper foil. Ferrite beads can do the same job. You goal is to prevent RF current to flow through the OUTER conductor of coaxial cable. Ferrite bead can do it well. May be the best solution is to use differential line with a balun, but it is just an idea. You know your application better. One more way is to coil several turns of coax around ferrite toroid or even just the coil them without the core. Depending of frequency it may work well. I have such a choke (no ferrite) in my home radio station and it works perfectly.
Thanks again for the reply, but please note that I am looking for a PRINTED VERSION NOT A COAXIAL VERSION!
I cannot implement anything which is not PCB based due to manufacturing requirement.