A Redstone Portal would be a connected portal, similar to the Nether Portal.
You would have to connect it to a Portal Box.
A Portal Box Would change the Image on the portal As each one would be chosen.
The Portal Box would be able to change which portal it goes to.
You would also be able to see where the portal leads to.
A button or a lever would control the box.
Mobs, Carts, Arrows, Thrown blocks, Ect. Would be Able to Go through it.
How to Make Objects-
Portal-Same Shape as the Nether Portal, Except Diamond Blocks Instead of Obsidian.
It would have to have the Portal Box Right On the Side of it.
Portal Box-3 Diamonds On Each Side, And Pattern Switch, Text Block, Button.
Also, You could Name The Portal.