FIG.1 below shows a shorten Dual-Band Dipole with overall length of about 11 m. For this antenna I do not use traps but simple inductors, in order to cover the 10 & 40 m. Bands.
L= 41 turns (close), 1mm wire on a plastic rod 2,5 cm diameter.
Using inductors, the total length of antenna is about 50% of a full size 40m. Band Dipole. For best SWR on 10m, you must increase or decrease the "A" sections. Then, looking for best SWR on 40m. by adjusting the "B" sections.
Have Fun !
B = 2.8 m
FIG.1
The internal part of antenna (2 "A" sections) is a full dipole for 10m Band. Then,
the inductors acting as "traps" for the rest length of antenna. On 40m. Band, the antenna works as coil-loaded
with some losses in efficiency, but on the other hand, it's a very small-size dipole for this band.
That is a good idea for a 40m-Band rotary dipole ( plus 10m ! ).
73, Dino SV1XY