BM [K5QWG],

What you say is correct if the Fan Dipole is being
used properly as a Single Band Amateur Antenna.

How Ever ! ! ! ) Take the same Antenna and . . .
[ Remember we have an Antenna built On-the-Fence
and for what ever reason {or lack of understanding}
the Shortwave Listener (SWL) has decided the a
Dipole is the only thing {Antenna} that they want.
Plus the want a Mutli-Band Antenna to cover a few
of the Shortwave Bands for Broad-Cast Program
Listening (BCL) ]

SO HERE WE GO AGAIN - - - - - - - - - - - - - -
This is a Three Band : 49 & 31 & 22 Meter Bands
Shortwave Listener (SWL) "Receive Only" Tri-Band
Dipole {Wire} Antenna built on a On-the-Fence
Question What Do We Do To Make It 'perfrom' ? ? ?
? To Perform - Or Not To Perform - - - Is That a Question ?
A little better across the Shortwave Bands so we can
"HEAR" a little of everything from 1.8 MHz to 30 MHz.
Not a good answer but never the less a fair answer is
the 4:1 Balun to 'smooth-out' the impedance mismatches
from the Three (3) Dipole Antenna Elements and provide
a fair 'match' from the three of them across the Shortwave
Bands; know that they are One-Foot, Three-Feet and
Five-Feet above the ground when Idealy they would be :
49m = 38.5 Feet above AGL
31m = 24.5 Feet above AGL
22m = 17.1 Feet above AGL

alas - it is an imperfect world - iane ~ RHF