Topband: Handheld Impedance Analyzer
Richard (Rick) Karlquist
richard at karlquist.com
Mon Mar 28 19:14:09 EDT 2016
On 3/28/2016 9:14 AM, Jim Brown wrote:
> On Mon,3/28/2016 4:37 AM, KE1F Lou wrote:
>> Is the lowest SWR is the resonant frequency?
>> Resonant frequency is when Xl=Xc.
>> When Xl=Xc is not necessarily the lowest SWR.
> Exactly right. If, for example, the antenna's feedpoint impedance at
> resonance is different from the feedline impedance, or if the analyzer
> impedance does not match the feedline impedance, the lowest MEASURED SWR
> 73, Jim K9YC
I don't believe the above assertion.
Can anyone give a specific example of an antenna having
an SWR at the resonant frequency, (where X=0), that is higher than
the SWR at frequencies slightly above or below the resonant frequency?
I submit that a local minimum in the SWR will always coincide
with X=0. This is easily proved on a Smith chart, where X=0
corresponds to the X-axis. Adding reactance or susceptance moves
the impedance farther from the origin in all cases, meaning
SWR goes up.
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