Re: [Amps] Re: AMPS Link coupling

["Ian White, G3SEK" <G3SEK@ifwtech.co.uk>]

G3RZP wrote:
>
>>Rich wrote
>>There is  no antenna matching network that has a lower Q than an 
L->>network.
>
> This is not correct. A parallel tuned circuit with a coupling  link, 
> loaded by a high impedance antenna can have its LC ratio determined 
> such as to control the value of Q. It is possible that self capacity of 
> the coil could be a limit in some cases.
Ignoring the unloaded Qs of the individual components from which a 
network can be constructed...

The minimum possible *loaded* Q that is required to transform between 
two resistances R2>R1, using any possible circuit, is sqrt(R2/R1 -1).

The L-network has exactly that value of loaded Q, so it is correct that 
no other network can go lower (at least for resistive loads; not sure 
about impedances in general).


--
73 from Ian G3SEK         'In Practice' columnist for RadCom (RSGB)
http://www.ifwtech.co.uk/g3sek
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