Experiments with Transmission Line Baluns
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- Опубліковано 30 вер 2024
- #207 In this video I continue looking at the transmission line baluns we analyzed last time by building and testing them out. Just to keep things simple, and working at low frequency, I build these form meters of cable, but as with any good experiment - not everything goes according to plan...
Balun series:
Ep1 - Communication lines and baluns • Communication lines an...
Ep2 - Voltage and Current baluns • Voltage and Current Ba...
Ep3 - Energy coupling • Energy transfer in Baluns
Ep4 - Transmission line baluns • Transmission-Line Baluns
Ep5 - Transmission line experiments: • Experiments with Trans...
Ep6 - The Ruthroff Transformer: • The Ruthroff Impedance...
Ep7 - The Guanella Transformers: • Analyzing Guanella Imp...
EP8 - LC baluns: • Building INDUCTOR-CAPA...
Further reading:
www.onetransis...
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Another great video. Thanks!
Thank you, I learned a lot.
my concern is what happens in the amateur radio world where we have a 4:1 half wave transmission line balun feeding the balanced 300ohm folded dipole... BUT UP AT THE ANTENNA THERE IS NO EARTH/GROUND AVAILABLE AT THE BALUN TO GROUND THE CO-AX SCREEN TO SO IT GETS LEFT FLOATING. How does this mess things up?.
👍
My friend, i think it's time you jumped to ADS for this experiment.
Not sure what ADS stands for...
Great presentation!
Did you ever simulate a broadband coax balun wound around a toroidal core to function as a sheath wave choke with LTspice?
I don't think I have, but I will probably expand this series in the future
@@FesZElectronics Thank you for your reply. Would you have any advice on how to start writing the spice commands? I may get a chance to start myself.
By the way, I remember having seen a capacitance meter and an inductance meter in one of your videos. Can you recommend them? Which types are they?
What I found out in the mean time is that if you want to model the inductance you get from a ferrite core - you can add it as an inductor in parallel with the transmission line - like the magnetizing inductance is modeled with a normal transformer. Maybe this will help. As capacitance meter I use a CM9601A (not sure of who the manufacturer is though) and for inductance I usually use an AX588B (from Axiomet) - these are not the best tools but they are relatively low cost.
Regarding the modeling, see fig.3 and the associated comments of course, maybe this will help - www.highfrequencyelectronics.com/Dec07/HFE1207_GrebennikovPart1.pdf
@@FesZElectronics Great inspiring article, thanks for sharing.
By the way, I very much like your work. Greetings from Germany to Romania.
Great “infotainment “…..lol
Also, a question. How did you specify the L parameter instead of Td parameter? LTSpice help file says that the length is derived from Td. And for lossy transmission line it's called Len, not L (L is for the inductance per unit length).
Well, I used both L and Len in my definition; I know from the datasheet the Capacitance/1m; and knowing the characteristic impedance, you can determine the inductance/1m - Z=sqrt(L/C); so L=Z*Z*C; the delay per unit of line is sqrt(L*C); and the model finally multiplies this by the LEN value.
@@FesZElectronics Yes, that works perfectly for lossy transmission lines. I was asking about the earlier section of the video, where you were showing lossless transmission line and moved from specifying Td (in nanoseconds) to specifying L (in meters). That's the part I don't understand.
For example, 8:36 - you use Td parameter to indicate delay. 11:50 - you use L parameter to indicate length. Or was it just for illustrative purposes?
Ah, sorry; yes, that was just to make the length clear... it wasn't a model that can be simulated.
@@FesZElectronics Thank you very much for the clarification. Now it makes the perfect sense.