[Antennas] efficient antenna tuning

[Don Havlicek]

DJED1 at aol.com wrote:

>OK- here's the answer to what I think you're asking:
>
>If you use an inexpensive antenna tuner
>
>at the rig, 
>
Using an antenna tuner at the rig will NOT tune the ANTENNA, but, 
rather, simply make the combination of antenna & feedline LOOK better to 
the rig.

>and you want to operate  
>all of 40 meters, then you should tune the antenna for resonance at  mid-band. 
>
Yes, the ANTENNA should be tuned a some point near mid-band, but, that 
is WITHOUT the antenna tuner.

> This will result in the minimum SWR on the coax,
>
SWR on the coax?  If you mean the APPARENT SWR at the RIG END of the 
coax , that is NOT true.  

> and will  minimize the 
>dissipative losses in the coax.  The impedance at the rig end  is affected both by 
>the antenna impedance and the electrical length of the coax,
>
Absolutely true.

>  so a general 
>purpose tuner is needed.
>
Not necessarily, as it depends on the capabilities of the particular 
tuner and the impedance range required for the particular antenna/coax 
situation.

> Similarly, if you only want to cover  the CW band, tune 
>the antenna to the center of the CW band. 
>
Very true, but not a good choice, as it will make things difficult in 
the future IF operations on the upper part of the band is desired.

>If you want to make the problem more complicated, you could ask for only a  
>capacitor as a tuner.
>
How do you suggest doing this?  Series with the coax, or parallel to it?

>  Then, you would want to tune the antenna and/or  adjust 
>the coax length so it looks inductive at the end of the coax.
>
I  do not believe that anyone would take time to trim the length of coax 
again and again to make the situation as you state.  If so, the time 
they would waste could be used to help me with all of the projects 
around here that need completion.

>  I  don't think 
>I can give you a specific answer without knowing the antenna  impedance versus 
>frequency, and an antenna analyzer is more expensive than an  antenna tuner.
>
Not true!  Some inexpensive analyzers are much less costly than some 
tuners.  That statement is too broad.

My suggestion is:  Put up the antenna you wish to use ... attach a good 
feedline from your rig through a good measuring device ... Bird ??? .... 
apply power ... and then, should the "SWR" be less than 2:1 ... have fun.

Don
N8DE

>Ed  WB2LHI
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