COMMON MODE CHOKE / BALUN And how to Measure the Choking Impedance Jacques Audet VE2AZX Web: ve2azx.net Rev. 1.2 Jan 2018. The balunis built in a plastic case (Hammond 1598JSGYPBK) Layout of the three coils. This arrangement minimizes coupling between the coils. The coax cable is RG-8X. The balun-function is done by the 180° degrees phase shift in L1. If you simulate the frequency and phase response for a 2.45 GHz signal with this 8.2 nH. Effects from the SoC, pad capacitance, bond wire inductance and capacitance, etc. Modelling of a Printed VHF Balun Using E-M Simulation Techniques 1. Structures that can create these phase shifts are called Baluns, BALanced to UNbalanced. Commonly these are. The inductance of the primary to give a good, if narrow band match, as shown in Figure 4. The phase difference between.
1:1 Balun
Balun Vs Choke
It is possible to make a balun with a 1:1 impedance transformation from coaxial cable?
This article
http://www.iw5edi.com/ham-radio/files/I0QM_BALUN.PDF
Coaxial balun by the radio amateur I0QM, claims to give a 1:1 balun from coax. However, I am highly suspicious of the validity of the arguments given. He uses two sections of transmission line (one λ/4, the other 3λ/4), to achieve a 180 degree phase difference. Well why not just use one bit of coax, of λ/2, or if more convenient, 0.1λ and 0.6λ?
Then it says 'As the electrical length of both sections include the ¼ wavelength coaxial transformer, and if the unbalanced impedance has the same value of the coaxial cable, then the impedance seen at the other extremes is exactly the same value.' Well, if the impedances are the same, we don't need any coaxial transformer.
So basically, unless I'm mistaken, this article is seriously flawed, in its technical arguments, although I'm not saying the design does not work.
This article
http://www.qsl.net/i0jx/balun.pdf
basically has the same design.
I've tried searching with Google Scholar to find peer-reviewed 1:1 coax balun, and can't seem to find anything.
Baluns are a bit of a black-art to me. There seems to be 100's of people writing about them, but I doubt 1% know what they are talking about. It's finding the 1% that is hard!
Dave