Electrical / Electronic Theory and Learning Center > Learning Center Miscellaneous
Antennas & Transmission Lines (feedlines)
Duncan:
I hope no one minds if I include this link which I think gives a pretty good description for the benefit of those who are perhaps not Hams but have an interest in the subject.
https://www.youtube.com/watch?v=w1eE13UXAKs
consider this ... as a broadcaster you transmit into a resonant antenna, In electrical terms a resonant circuit uses no ' real power' ergo power = VI cos Φ = 0 of course this is a perfect world we consider perfect resonance and perfect conversion to the EM wave.
In the radio world we are familiar with here ends the tale.
However there is a huge BUT ... This 50 ohms you consider is initially a design factor of the transmitter its arbitrary .. It could be anything. There are of course also two distinct resonant points where VI cos Φ = 0 one where the voltage leads the current by 90 deg and another where current leads the voltage by 90 deg (in electrical terms series and parallel resonance) The series resonant wireless system (tends to) transmits electrostatically through the ground whilst the Radio system (tends to) transmit electromagnetically through the air. The far more efficient electrostatic wireless system of Tesla and the very different electrical theory associated has been buried for over 100 years. still either side of the two resonant conditions is miss match ... spurious emissions of immense power can turn up anywhere on the globe, obliterate whole bands and probably not make you very popular down you street! :-[ kind regards Duncan
Centraflow:
Poynt
Why have an antenna design which is a mismatch in the first place (150 ohms) when the transmitter is 50 ohms, or am I missing something :-\
regards
mike 8)
Centraflow:
Duncan
ELF (extra low frequency) is primaraly an earth transmission, hence used for submarine communications. It is a bit like in reverse, the air becomes the earth and the ground becomes the arial, it can only be done in select sites on the earth, one of which was close to my home town, the reason being of underground aquatic and plate connection.
regards
Mike 8)
Duncan:
Hi Mike great talking to you again, O0 it had slipped my mind that you are one of a relativity few to have worked practically in this area .certainly where I lived any transmission out of the ordinary would have been jumped on very quickly with dire results (as you know) still it wasn't a frequency I was thinking of be it ELF or UHF but rather transmission method. more Specifically the method considered by EPD here
https://www.youtube.com/watch?v=f5ZWrjcrPl4 from 1M 30 sec on and further demonstrated here by the old scientist
https://www.youtube.com/watch?v=wjz-5Lqtxow
as EPD tells this is created by making use of and transmitting the series resonant state O0 of course extrapolating from that many things are altered
kind regards Duncan
Centraflow:
Duncan
It was as a reference to Tesla and EPD who both used the earth as the main means of transmission, not the atmos: and with no losses. The problem is for information transmission it is very limited, morse only. Sub's nowadays still have this, but their main system is via sat's but needs a buoy floating on the water and a wire down to the sub, not always possible in times of war.
I could explain your circuit as I have with video some time ago concerning the 3BGS. The 3BGS will only work for a short time until the chemistry changes in the battery.
I am going to start an open thread on a similar theme where Kirchoff's law does not apply :D
regards
Mike 8)
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