"OK1SIP" wrote
"Reg Edwards" wrote
There is NO antenna which will allow high radiating efficiency on all
bands without a tuner. ...

Hi Reg,
the antenna at http://www.qsl.net/w5dxp/notuner.htm should cover all
bands except the topband without a device called "a tuner". Of course
it has a tuner of its sort - a set of switchable pieces of twinlead.


Hello Ivan,

I am familiar with Cecil's binary-switched variable-length feedline. We are
friends and I hope to keep things that way. ;o)

In terms of expectations, quite correctly you say "*should* cover all bands"
rather than "*will* cover all bands". Actually it doesn't cover (tune) any
band.

As a fundamental principle every tuner must have at least two variable
components because it has to match Z = R+jX which also contains two
variables. In more practical terms a tuner must have at least two knobs, for
example, one to vary L and another to vary C.

So it is impossible (or at least extrememly inconvenient) for a transmission
line to behave as a tuner because only its length can be changed. Unless, of
course, Cecil can invent a way of varying its impedance Zo between, say, 100
and 600 ohms.

But bearing in mind Cecil's primary objective in using a 'tuner' is to
provide a load which will keep the transmitter happy, without regard to SWR
on the variable-length feedline, his arrangement is successful. It is
necessary only for the transmitter to be happy provided its load indicator
has a reading which does not exceed much above 1.5 to 1. (SWR).

Whether or not the station operator is happy using a tuner with one of the
knobs missing is another matter.

The behaviour/performance of Cecil's 'tuner' can be very accurately modelled
using program DIPOLE3. Download in a few seconds from website below. Just
vary frequency or line length and watch the line input impedance.
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Regards from Reg, G4FGQ
For Free Radio Design Software
go to http://www.g4fgq.com
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