IF: All Transmission Lines & Antennas Are Conductors AND: All Conductors Block Radio Frequency (RF) THEN: Why Do They Work?

[paulears]

To understand a definition, you need knowledge and context. If you know, the. Your interpretation is based on your existing knowledge. This question, frankly, is a very poor one to be in an exam, because the inclusion of the word ‘if’, is actually a question. It translates to “is a cable a transmission line?” Which could be yes or no. The correct sense would be “a cable, operating as a transmission line”. Couple this with “ under what circumstances does a cable block RF current?” And you get the option to use science and context. If they used the exact wording in the title of this topic, then that is inept exam question creation. It is, however, a good question if the purpose is to create discussion that reveals knowledge. Remember that real exam boards, not Governments or societies, rarely ever require people to understand, because it’s impossible to quantify understanding. “students must understand Ohm’s law”. Then we start to talk about impedance, rather than resistance, which generates so much misunderstanding.

 

[thunderr10]

Hello Hams and Radio Enthusiasts,

This is a question that arose in my mind while studying for a week and passing my initial Ham Testing for Technician, General, and Amateur Extra. I have yet to find a solid answer.

A seemingly simple question, yet like many other of the "Simple Questions" in the world of Radio require a bit more homework. This specific question I cannot seem to find a solid answer, other than, "They just work that way"...

OK, neat... why do they work that way?

I've read entire Antenna Books, ARRL, etc., and I probably missed it, but I cannot find the answer this most basic question.

If all Conductors block Radio Frequency (RF), then why do all Transmission Lines and Antennas, which must be conductors, transfer or transmit and then receive RF? Seems to be a very paradoxical question yet easy to answer question.

Any super smart experienced Hams and/or Radio Experts out there who can answer this?

Please & Thank You in Advance!

I have my suspicions, but will refrain from providing them for this OP.

73's

Ryan, AE0TO
o7

Alien Technology

 

[Sheepdog777]

Alien Technology

23 Year USAF Retiree Here...
Top Kek!

 

[ArloG]

Google Coaxial Stub Filters. Tell me what you think.

 

[KevinC]

I know, crappy picture. But a little known USAF project.

 

[Sheepdog777]

I know, crappy picture. But a little known USAF project.

Oh I know the SIO...

o7

 

[KevinC]

Oh I know the SIO...

o7

“Integrity from earth to stars”

 

[RU55]

Any time there is a change in current, in a conductor, an electromagnetic field is created. Any time a conductor is exposed to a changing electromagnetic field, a current is induced in the conductor.

If you create a "cage", or area, completely surrounded by a electrically conductive material, a radio wave, which is alternating (constantly changing), that encounters the conductor will be converted into current in the conductor of the "cage". By converting the RF into a current in the "cage", the [electromagnetic] RF is essentially blocked.

That is how an electrical conductor can conduct RF and still be used to block electromagnetic RF.

Keep in mind that there is a difference between RF current and electromagnetic RF. An electrical conductor can act as a transducer, converting electromagnetic RF into RF current in the electrical conductor.

 

[merlin]

Think like this, ,if you were not sleeping in science.
An audio oscilator through an amp, frequency 261.63 Hz (C/4)
across the room, a guitar string vibrates.
Much the same with RF but much higher frequency, high enough it is electro magnetic.
It radiates, it can be refracted, reflected and absorbed.
About antennas and feed lines, get a coppy of the ARRL antenna book.

 

[merlin]

Similar question: Glass passes light, lenses are made of glass and can focus light and prisms are made of glass but reflect light.

Prisms can also refract light and a lens is sort of a prism.