[Elecraft] Trap dipole fed with ladder line?

[Stuart Rohre]

Jeff, while the reasons you cite are valid, keep in mind that any trap
antenna has more loss if using fixed traps of coils and caps than a straight
wire.

Also, a doublet can be shortened to 60 per cent of a half wave and still be
well up in the 90 per cent efficiency range.

The only advantage other than pattern preservation to trap dipole, is that
it is typically shortened for each band due to trap loading effect.

But by applying the 60 per cent shortening, and feeding with parallel low
loss line, you avoid the losses of LC traps.  The use of linear stub
decoupling is another option, but will probably end up longer overall.  The
Lattin antenna is one stub decoupled type of multibander.  It is on the
G3YCC memorial web site, but has an error in the first 8 foot section.  BOTH
sides of the parallel line used as conductor for the 8 foot should join the
feeder at the center insulator, on each side of it.

 You will have lowest loss on lowest band with the shortened, parallel line
fed dipole wires.  L. B. Cebik shows an 88 foot doublet as a good compromise
length to preserve patterns as well, for the higher bands.

Lumped constant traps are always a loss factor.
73, Stuart K5KVH