Looking for a simple balun for the spiral antenna

[lasermaser]

Hi.

I am looking for a simple balun for the spiral antenna. There has been many topics that are similar to mine, but I cannot find the answer that I am looking for. The balun should be really simple and made from coax cable. I think that the description below would do it (from: https://www.edaboard.com/threads/91409/ ), but I cannot find anywhere more details about it:

Another approach is to take a coaxial cable (like 0.141" semi rigid or even smaller) and cut the shield with a long diagonal cut. You will end up with a shield looking like the business end of a hypodermic needle. The sharp end of the taper and the coax center conductor now form a balanced line. These are fairly easy to fabricate if you have access to a friendly machine shop. There is the risk of slight beam squint with this one.

Can anyone give me more details about it, or at least tell me how it is called. I cannot find anything useful on google or anywhere else.

The bandwidth needed is only about 10% of the center frequency. My spiral antenna has two arms.

If someone has other idea that would be simple (I don't want to complicate with pcb-s etc.) it is also more than welcome.

Thank you very much.

 

[eagle5]

Have you considered using ferrites around the coaxial cable? Although their performance is not great, they are a cheap fast solution.