Another thought: there were a series of antennas,
in the late '60's-early '70's , for vhf (Mainly
2 Meters), called "Skeleton Slots" (think by "J"
beams). These consisted of stacked yagi antennas,
fed by the equivalent of a slot antenna ,Driven el
portions at the narrow's top and bottom, to
each yagi. The (rectangle) fed in the middle at
the narrow center, as you would a traditional slot
antenna .
(I am NOT claiming that this was the most
effecient, just noteing it as it seemed to work
for Stacking yagi pairs ).
Might, therefore try a rectangle version of a quad
element, fed at the narrow center. Tho dont know
how much deteriation would be from the slot in an
infinenate field , possible to use as a simplified
model ?? Might give it a try ?? Jim NN7K

Denny wrote:
Let me simplify the highly detailed explanations you have received...
1. Model the slot as a rectangle/loop antenna of fine gauge wire.
2. Model the outside edges of your antenna as another rectangle/loop
antenna.
Fill in the area between the two rectangles that is solid metal with a
criss cross of connecting wires.
3. Create a transmission line to feed the two long edges of the slot at
mid point...
4. Be aware that Mininec engines are going to be a bit iffy with this
kind of structure... But at least you get some ball park figures..

denny / k8do