Re: LF: EbNaut and The Cat / Take 3

[Andy Talbot <andy.g4jnt@gmail.com>]

But since that does explicitly include F^2, it is a moot comparison, that isa secondary realationship.  

You could use the same argument relating dB to a loop where it scales as diameter ^4  (or area squared) 

Then gain =40.LOG(f..)

I think the use of dB = 20.LOG (V or I or [what else]) has caused an awful lot of confusion over the years

I'm of the opinion that dB should always be explicitly 10.LOG  and if you want to input V or I or [whatever] then state that that parameter is squared in the equation   ie   dBW = 10.LOG(I^2 . R)

[what else]   - sound intensity or  ... ? or ...?   What other parameters are squared to give energy or power?

Andy  G4JNT

But then, maybe not - consider radiated power from a given antenna height and current

 Prad = i^2 * 1579 ohm * (h / lambda)^2

which clearly scales with f^2.

 

So, in the essence of it's innermost being, "Frequency" remains a mystery ;-)

Best 73,

Markus

 

-----Ursprüngliche Mitteilung-----
Von: Andy Talbot <andy.g4jnt@gmail.com>
An: rsgb_lf_group <rsgb_lf_group@blacksheep.org>
Verschickt: Mi, 25 Nov 2015 6:32 pm
Betreff: Re: LF: EbNaut and The Cat / Take 3

Moving to 496.4Hz now ?

Frequency expressed in dB has to take the 10.LOG form, not 20.LOG

Consider P = kTB  

'jnt

Thanks also from here to all participants (feline and human)! Next step - reduce frequency by 24.4334 dB?

 

All the best,

Markus (DF6NM)