If by effective you mean one that migrant workers cannot get over, under or through, you will never see that.
Do you know that the Berlin Wall never stopped one single person from crossing into West Berlin? It didn't. The guards with machine guns every fifty yards in towers and on the ground stopped people who otherwise would have simply climbed over the wall.
Fences are excellent for stopping vehicles and for delineating borders, but they have never stopped people from crossing. (And now one is being built in New Mexico to prevent Mexican cattle which might be diseased from crossing.)
When you were in the Seals and your unit came upon a chain link fence did you give up your mission and return to base saying the mission was impossible because of a chain link fence? What about a wall or a river or a "no trespassing" sign? No matter how tightly you squeeze your eyes and wish, wish, wish, there is no magic fence, only 102,000 miles of land border and shoreline which would require well over three million guards to patrol as long as we fail to enact the necessary reforms that would allow us to secure the border.
PS: A magic fence would not have stopped the estimated 50% of illegals currently in the U.S. who entered legally and didn't return after their visa or permit expired.