[Antennas] increased antenna bandwidths through a tuner, why?

[Gene Mason]

   Sam,

       In  a  word  you  are  reducing  the  Q of the apparent load, your
   antenna.  In  all  actuality you are padding the load , as to create a
   more  desireable load for the transmitter. You really are not changing
   the antenna characteristics of the antenna.

   The  only way to do that is to insert a network  at the antenna end of
   the  transmission line, in which case you wont need a tuner, if you do
   it right.

       This is the most difficult aspect of an efficient antenna, and the
   least  understood.  The modeling programs make the solution simple, by
   providing  the  network to use with a 50 ohm transmission line. And we
   all  thought all there was to an antenna, was an equation to calculate
   the resonant length.

      Gene KZ5V
       ______________________________________________________________

     From:  Sam Morgan <ka5oai at cox.net>
     To:  "antennas - qth.net" <antennas at mailman.qth.net>
     Subject:  [Antennas]  increased antenna bandwidths through a tuner,
     why?
     Date:  Sat, 29 Apr 2006 07:27:08 -0500
     I  have  a bugcatcher set with 1:1 at center frequency of 7.09 with
     no tuner.
     It has a base coil taped for minimum swr.
     When I check the 2:1 to 2:1 bandwidth it is about 76kc.
     If I run it through my home brew T-tuner, and set the tuner to have
     the same 1:1 at that same 7.09 frequency, I then get a bandwidth of
     151kc. (not touching up the tuner further than when I set it to 1:1
     initially).
     The  tuner  is  set  with  both  caps  @ 50% and the (small) roller
     inductor is set at about 7 of 17 turns out from minimum inductance.
     It makes me happy, sure, but I'm wondering if someone would explain
     it to me.
     How  does it increase the bandwidth if the same 50ohm feed point is
     there with or with out the tuner.
     --
     GB & 73's
     KA5OAI
     Sam Morgan
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