Buck wrote:

so, how does one make a 94 ohm match? [at both 7 and 21 MHz]

1. A 2:1 transformer.
2. An LC network. I think at least three components would be necessary
for matching at both frequencies, and an exact match would probably
require four.
3. A number of different schemes using transmission line stubs.
4. Don't bother. There's nothing wrong with a 2:1 SWR. Feedline loss
will reduce it further.

A couple of other notes:

I often use a 40 meter dipole for 15 meters on Field Day. I put a small
inductor at the feedpoint to bring the resonance down to the bottom end
of 15; it doesn't have much effect at 7 MHz. (If it did, I could get
resonance on both bands by alternately adjusting the antenna length and
inductor value.)

You can make a nice bidirectional pattern with some gain in two specific
directions on 15 by bending the wires toward each other by 30 degrees to
make a horizontal vee with 120 degree included angle. This only has a
minor effect on the pattern on 40 meters.

Roy Lewallen, W7EL