[Antennas] Re: increased ant bandwidths...

[Robert Lay (W9DMK)]

Dear Saandy,

I don't think there is any controversy or disagreement with regard to the 
basic operational concepts involved here. Where there might be a difference 
of opinion is in regard to how bad the losses can be in a tuner. There have 
been some carefully done experiments reported in QST over the years that 
make it quite clear that the losses in antenna tuners are a lot more than 
most people would imagine.

73 de W9DMK - Bob Lay, Dahlgren, VA
http://www.zaffora.com/W9DMK/W9dmk.html
w9dmk at crosslink.net
----- Original Message ----- 
From: "Saandy Eban" <alexeban at bezeqint.net>
To: "'Jack Painter'" <223bthp at cox.net>; "'Antennas reflector'" 
<antennas at mailman.qth.net>
Sent: Saturday, April 29, 2006 3:40 PM
Subject: RE: [Antennas] Re: increased ant bandwidths...


> ...why should it change?
> Try to look at the antenna AND the transmission line as a single
> entity: as long as the antenna coupler brings the system to accept power
> that power, minus ohmic losses, WILL get out! The conservation of energy 
> law
> works!
> the main reason for not throwing the open wire feeder out is this: a
> SWR of 10 or 20 will not add more than a few % of power loss, directly
> attributable to the SWR! Because of this it hardly matters what you see
> there: what matters is that the radio will see an SWR it can live with. If
> you ensure that, everythin going into the system WILL get out, again,
> barring the inherent ohmic losses. On the other hand, if you can 
> compensate
> for such SWR's, you can cover half of the HF spectrum with one antenna.
> An SWR meter has no place there (the antenna side, that is) but an RF
> ammeter will allow you toverify a current maximum in the antenna, which is
> basically what counts.
> Saandy 4Z5KS
>
>
> -----Original Message-----
> From: antennas-bounces at mailman.qth.net
> [mailto:antennas-bounces at mailman.qth.net] On Behalf Of Jack Painter
> Sent: Saturday, April 29, 2006 8:50 PM
> To: Antennas reflector
> Subject: RE: [Antennas] Re: increased ant bandwidths...
>
> Bob and Roy,
>
> It sounds like you both agree that power output from the transmitter is 
> the
> only objective of any antenna tuner. What happens after that we have to
> accept if we want wider use of each antenna.
>
> If antenna tuners were placed at the feedpoint of the antenna, there would
> be little reflected power on the transmission line before it. An antenna
> coupler is always as close to the feedpoint as possible for this reason.
>
> When we want more tuning options in non-weatherproof assemblies right at 
> our
> fingertips (and inside the zone of our lightning protection system), we 
> have
> to accept the consequences. An inside antenna tuner still protects the
> transmitter and the operator, as long as we remember the output of the 
> tuner
> (like a coupler) is 'hot' in more ways than temperature.
>
> Regards,
>
> Jack
>
> -----Original Message-----
> From: Robert Lay (W9DMK)
>
>> Ordinarily RF power meters are located at the INPUT of an 'antenna
>> tuner.'
>>
>> 73,   Roy     K6XK
>
> Good point, Roy.
>
> We wouldn't want anyone finding out how little power comes OUT of the
> antenna tuner - that would discourage people from using them.
>
> Even worse would be to have an SWR meter on the output side of the tuner.
> Then they would really be pissed to see that the SWR does NOT CHANGE AT 
> ALL
> in the transmission line - Hi!
>
> 73 de W9DMK - Bob Lay, Dahlgren, VA
> http://www.zaffora.com/W9DMK/W9dmk.html
> w9dmk at crosslink.net
>
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