Raptors like a tree with big dead branches at the top. Or a tall (20-30 feet) pole with crossbars.

If you have an open meadow or field, redtailed hawks like an 8-10 foot T-shaped pile at one side of the space. They especially like it if the pole is at the top of a slope.

Suggested diameter and length of these crossbars?

about 3 inches diameter and a couple of feet long Think of a laundry t-pole with shorter crossbar.

They also like perching on the flat tops of fenceposts. When I drove I-5 in California there would ba a hawk on a fencepost every half mile or so, just watching the fields for mice.

Our local raptors perch in trees around the yard, front and back, both Coopers Hawks and Red Tailed. I got a video of a Coopers Hawk that perched on one of our bird baths (used as a planter), and he/she allowed me to take a video. If you put up a very tall, VERY tall pole etc... you'll have more than hawks perched there too. Vultures love to perch up high like that. We live on a bluff so see everything, and we had a black vulture pair that would perch on a neighbor's CB tower before he took it down. They still fly over every day and sometimes perch in our trees above the house.

I have a U shaped pole assemblage in my backyard my father used to use for pullups. There is a hawk that uses it to perch on to hunt snakes in my yard. Its made of galvenized steel poles. But the hawk also likes to perch on some poles out farther in the yard, the poles are just wood poles the diameter of a telephone pole but shorter(maybe 7ft tall), the poles orginally were for grape vine wires but have not been used for that for a long time.

Some time this last winter, I saw a hawk pecking at something about 75' away. I set my binoculars on a tripod and used my phone to take the pictures.