How well do we really understand RF?

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How well do we really understand RF?

Postby lars » Fri Feb 10, 2017 9:39 am

Hi folks

It occurs to me to wonder whether we -- that is, humanity in generally -- really understands RF propagation and antenna theory. I don't doubt that we can work out the behaviour of ideal antennas made of ideal materials in an infinite volume of free space; but I wonder how much of that theory really still applies in practical applications?

Books, websites, and personal conversations are full of conflicting advice about antenna construction and installation. I can't help thinking that if we _truly_ understood this stuff, the 'right' answer would be known in most practical applications. But I suspect the advice given by most authorities is based on experience and rules-of-thumb rather than on theory. So relatively minor changes in the operating conditions and environment could mean that a particular person's advice, however much based on long experience, is not helpful.

So do we understand this stuff? Is it even worth studying the theory?

Best wishes
Lars
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Re: How well do we really understand RF?

Postby m0lsx » Fri Feb 10, 2017 11:49 am

The problem is you cannot confuse conversations, which may be very well informed & specific with conversations that are ill informed & about generalities.
Propagation is VERY dependents on specifics. What is the soil like under the antenna? How high is the antenna? What is the path like between the antennas? What form of propagation is being used? What design is the antenna? What band was being used? What time of day was it? What season of the Year? And several other specifics.
If you want a good basic book for the basics of propagation then Ian Pole G3YWX has just the book for you. Radio Propagation. Principals & practice. It only costs a few pounds, is under 100 pages long & just gives you very basics of what is a very complicated topic.
Radio Propagation is available from the RSGB & is well worth reading as it covers things like path loss, multi path, grey line, ionospheric & tropospheric propagation & more. But in basic easy to understand language.
Buy a database from Kimmy JS19 via http://ukscanningdirectory.co.uk/
Or do Google search of this forum via https://www.google.com/cse/home?cx=partner-pub-6291336405621919:2662881632
73 De Alan (M0LSX.)
http://www.qrz.com/db/M0LSX"
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Re: How well do we really understand RF?

Postby lars » Fri Feb 10, 2017 1:25 pm

It's fifteen quid now :) I've ordered one, anyway.

I think part of the problem might be that it isn't really possible to explain difficult stuff in easy-to-understand language.
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Re: How well do we really understand RF?

Postby G4RMT » Fri Feb 10, 2017 9:32 pm

Jim Bacon - the ex-ITV weatherman (and licensed ham) is really into propagation and has the knack of explaining things so ordinary people understand.

Worth a look at these youtube videos too
https://www.youtube.com/channel/UCnfnPpcvCwxqlNDHX_bJIXg
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Re: How well do we really understand RF?

Postby m0lsx » Fri Feb 10, 2017 11:01 pm

Jim is a friend of Steve Nichols G0KYA who is also a big name in propagation.
They both also live close to Norwich.
http://g0kya.blogspot.co.uk/
Steve does predictions for Southgate ARC's news site among others.
Buy a database from Kimmy JS19 via http://ukscanningdirectory.co.uk/
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Re: How well do we really understand RF?

Postby SporadicE » Sun Jun 25, 2017 3:57 am

A big problem is we still don't understand the origins of electromagnetic radiation. What is magnetism? We don't know. Until we can answer THAT most basic of questions, we'll be in the dark about related topics.

All we really know is that we pass a current through a wire, and we get an electric field in one plane, and a magnetic field in another plane. Why is still ?????????????

:thumbup:
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