[Elecraft] Antenna Analyser - Phase Angle Sensor

[Jack Smith]

Don Wilhelm wrote:
> Folks,
>
> There is an error in the reply I sent last night (below) that is very
> important - it makes a big difference.
>
> When increasing or decreasing the frequency to determine the sign of the
> reactance:
> One must observe the increasing or decreasing of the IMPEDANCE (Z) and not
> just the reactance.
>
>   
>   
You can note in Larry's VNA data that |Z| has four inflection points and 
that phase = 0 at each inflection point.

i.e., if d|z|/df = 0
where f is frequency and the d symbols refer to differentiation

there must be a phase zero, which can be seen to be true, since only an 
impedance with a net zero reactive component will have no change in 
impedance with frequency.

This is one of the three definitions of parallel  resonance. The 
interested reader can find the other two definitions in Terman's Radio 
Engineer's Handbook, amongst other places.



Jack
www.cliftonlaboratories.com