A Quick Look at Different Transmission Lines (
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- Опубликовано: 12 май 2024
- I thought it would be a good idea to show how each different type of coax works and explain the function of it. Watch to learn more about the different types of coax.
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Edited by Aidan Jakeman
Videographed by Teagan Kulbeth
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#coax
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Still miss the old leaning lamp
Thanks!
Messi & Paolini in Italy makes excellent Coax and connectors. Top notch quality in my opinion!
Thank you, Dave.
Mostly used coax for amateur radio. Has done the job. N0QFT
Dave, it is my bad that I have to make a harsh comment here.
At 5.04, it is you who is doing the misinterpretation of what happens in a coaxial cable; I feel sad that this is not the first time you say like this despite me trying to point out several times in your previous videos.
Let me try to reiterate one more time for the benefit of everyone here.
A coaxial cable behaves like three conductors all at the same time because of the phenomenon called the skin effect.
Yes, HF (RF) current flows only on the surface of a metallic conductor. This is unlike the DC that occupies the whole thickness of the conductor.
As the frequency of the AC (RF) gets higher and higher, the lesser becomes the thickness the current occupies due to the skimming effect.
Consequently, the coaxial cable has three surfaces for the current to flow.
1. The outer surface of the inner conductor.
2. The inner surface of the outer conductor.
3. The outer surface of the outer conductor.
Whenever a current flows on the outer surface of the inner conductor, there is an equal magnitude of current flows on the inner surface of the outer conductor but of opposite polarity.
Suppose that the cable is connected to a voltage source (Tx) at one end and to a load (an antenna) on the other end.
There won't be any current flowing on the outer surface of the outer conductor.
The electric and the magnetic fields, due to the flow of currents inside the cable, would be confined to the dielectric medium of the coaxial cable.
There should not be any current, I repeat, on the outer surface of the outer surface of the outer conductor.
What you have failed to appreciate (or realize) after this long is quite evident, whenever you talk about CMC and grounding the coaxial cable before it enters the radio shack.
By grounding, we mean only the outer surface of the outer conductor of the coaxial cable. Time and again, you talk about using a GDT type "static bleeder" on the ground stake. Let me reiterate that it is not a lightning arrestor (as often erroneously told by you and believed by many) but a static bleeder only. A static bleeder is no way near to a direct hit by a lightning bolt.
You used to say again and again that a CMC flowing on the outer surface of the outer conductor can be grounded by a grounding rod attached to the coaxial cable before it enters the radio shack. That is a wrong assumption.
Please try to consult the ARRL antenna book again and again to get a clear picture of the basic principles.
Many people have great faith in your channel. Let them not be misinformed.
Moreover you called the 450 ohm commercial window line as ladder line. Ladder line is one that is homebrewed to have an impedance in the range of 300-600 ohm depending on the spacing distance between the two conductors.
The purpose of the windows or slots is two folds.
One is to reduce the weight as you said.
But the important reason is to leave only less polyethylene dielectric and more of air to maintain the characteristic impedance and at the same time to sustain high voltages that would occur due to high SWR. Yes, open wire, twin lead or ladder line is used on multiband wire antennas with more than 95% efficiency despite high swr.
In high power commercial radio stations the open wires are used, as you all know.
This is in the good spirit of radio hobby.
De VU2RZA
IM NOT TAKING ANYONES PART BUT I DON’T THINK YOU NEED TO READ ANYMORE, FOR ONE THING YOU DONT KNOW WHAT YOUR TALKING ABOUT, this comment is just for the fun of the hobby 😂
5:04 Yes, it is very easy to misinterpret, and I believe you have. Or you're making some other point which is totally eluding me.